URBANIZED AREA NETWORKS STUDY
Task A
Standard Highway Network Procedure
Final Report
Prepared by
impeler-Corradino A SS ociates FLORIDA DEPARTMENT OF TRANSPORTATION URBANIZED AREA NETWORKS STUDY
Task A Standard Highway Network Procedure Final Report
Prepared for Florida Department of Transportation
Prepared by Schimpeler-Corradino Associates
May, 1981 TABLE OF CONTENTS
Page
LIST OF FIGURES ...... iv
LIST OF TABLES ...... * . . V
1. OVERVIEW . . ...* ...... 1
1.1 PURPOSE . l ...... * ...... 1.2 TYPES OF NETWORKS ...... 1.2.1 Existilng System Network ...... 1.2.2 Adopted Plan ...... 1.2.3 Nee ds Plan ...... 1.2.4 Interim Year System ...... 1.3 BASE MAPS......
1.4 MYLAR HIGHWAY-NETWORK MAPS ......
1.5 DATA PROCESSING ...... : ......
2. FORMULATION OF HIGHWAY NETWORKS ...... 6
2.1 IDENTIFY THE STUDY AREA AND DIVIDE THE AREA INTO PLATES. . 6 2.2 DETERMINE TYPES OF FACILITIES 12 2.3 ESTABLISH THE TRAFFIC ANALYSIS iONE; : : : : : : : : : : : 14 2.4 LOCATE THE CENTROIDS ...... 19 CONNECT CENTROIDS TO THE HIGHWAY NETWORK ...... 20 ::: LOCATE AND DEFINE NODES...... 21 2.7 DRAW MYLAR HIGHWAY NETWORK MAPS ...... 24 2.8 DRAW MYLAR TAZ MAPS ...... - ...... 27 NUMBER THE NODES ...... , ...... 28 221; BEGIN NETWORK CODING ...... 33 2.11 INSERT TOLL LINKS AND EXTERNAL STATION CONNECTORS . . . . 34 2.13 PLOT THE NETWORK ...... 39 2.14 DRAFT THE NUMBER OF LANES AND TYPE OF FACILITY ON THE MYLAR HIGHWAY NETWORK MAP ...... 41 2.15 ESTABLISH AREA TYPES ...... 42 2.16 ESTABLISH SCREENLINE AND CUTLINE LOCATIONS . . , . . . . . 46 2.17 ESTABLISH DISTRICTS ...... 47 2.18 POST TRAFFIC COUNTS 48 2.19 ESTABLISH CONSTRUCTION CODE; : : : : : : : : : : : : : : : 49 2.20 CODE NETWORK DATA . . . . . 50 2.21 CODE TURN PROHIBITOiS- : : : : : : : : : : : : : . . . . . 52 2.22 PLOT THE NETWORK DATA . . _ ...... 55
3. COMPATIBILITY OF ZONES AND NETWORKS ...... 60
3.1 GENERAL DISCUSSION ...... 60 3.2 TRIP GENERATION AND DISTRIBUTION CONSIDERATIONS . . . . . 61 3.3 SCREENLINE AND CUTLINE CHECKS . . _ ...... 62
ii TABLE OF CONTENTS (CONTINUED)
Page
4. NETWORK UPDATING ...... _ _ 63
4.1 OBTAIN HIGHWAY NETWORK MAPS 63 4.2 OBTAIN A LIST OF THE HIGHWAY N;ThOkK_L;NK iIiE- : : : : : : 64 4.3 DRAW THE NETWORK CHANGES ON THE BLUE-LINE WORK MAP _ _ _ _ 64 4.4 PREPARE THE MYLAR NETWORK MAPS ...... 64 4.5 CODE THE NETWORK CHANGES ...... 64 4.6 PLOT THE NETWORK ...... 65
5. STANDARD DATA SET NAMES ...... 66
5.1 COMPONENTS OF DATA SET NAMES ...... 66 5.2 ON-LINE DISK DATA SET NAMES ...... 70 5.3 OFF-LINE DISK DATA SET NAMES ...... 73
iii LIST OF FIGURES
Figure Page
2-l Network Development Flow Chart ...... 7 2-2 Network Plate Coverage ...... 2-3 Links per Zone Relationships ...... ii 2-4 Dummy Nodes and Links ...... 2-5 Network Map Legend ...... ii Node Numbering ...... 31 22:; Node Number Placement and Lettering ...... 32 2-8 Insertion of a Toll Link ...... 36 Area Type Example ...... 45 ;:;0 Turn Prohibitors ...... 53
iv LIST OF TABLES
Page
Table
2-l Definitions of Facility Type ...... 13 2-2 Definitions of Area Type ...... 44 2-3 Network Coding Summary ...... 54
5-l Standard Two-Character Study Area Identification .... 67 5-2 Standard Network-Related Data Descriptions ...... 68 5-3 Standard Network-Related Optional Words...... 69 Category Field Definitions ...... 71 5:; Data Type Words ...... 71 5-6 Year/Alternative/Version Words ...... 71 5-7 On-Line Disk Data Set Names ...... 72 5-8 Off-Line Disk Data Set Names ...... 74 1. OVERVIEW
1.1 PURPOSE
The purpose of this report is to define a standard network procedure.
A standard procedure allows an analyst to move from one study to another with little adjustment, promotes good practice consistent with the state of the art, identifies options that work best for Florida's urban areas and the Florida Department of Transportation's data processing facili- ties, and ensures compatibility with the "standard model" effort.
Although the subject of this report is the coding of a new highway net- work, it also serves as a guideline for reviewing highway networks now in use. If a network does not conform with the specifications described herein, it is not standard. Non-standard networks should be corrected unless the non-standard feature is needed to support a non-standard mode ing procedure.
TYPES OF NETWORKS
Existing System Network
All of the urban areas have developed or are now developing a 1980 high- way network for the purpose of updating and validating the models with the data gathered in the 1980 Census. It is very likely that all new models and networks developed during the 1980's will evolve from this existing system network. It is also anticipated that the existing net- work will be updated annually as a surveillance tool. Thus, the first priority should be to bring the 1980 networks in line with the standard procedures.
1 1.2.2 Adopted Plan
The adopted plan network represents the long-range highway plan. The plan must be economically feasible and responsive to anticipated changes in funding levels. This plan has an official status, as it must be adopted by the Metropolitan Planning Organization (MPO) and Florida De- partment of Transportation (FDOT). Furthermore, all highway design and construction must conform with this plan to receive federal and state funds. On the other hand, the MPO can change the plan. The plan is exa- mined and re-adopted on an annual basis. This means that even after a transportation plan has been developed and adopted, it can be changed
(continuing planning) and the travel demand models will be applied to evaluate the changes. For the travel forecasts to be accurate, the high- way network in the adopted plan should conform with the best network coding practices, as defined in the standard highway network procedures.
Thus, the adopted plan should receive the second priority.
1.2.3 Needs Plan
The needs plan represents the highway system that will satisfy all travel
needs at a specified level of service in the target year of the study, without regard to implementat ion cost. Not all study areas have developed
a needs plan. In the usual scenario for developing a transportation plan,
a needs plan is developed first and is then cut back, reducing the capital
cost to arrive at an economically feasible adopted plan. The needs plan
is used after a plan has been reappraised as a tool to evaluate a con-
templated change in the adopted plan. The needs plan should receive third
priority.
2 1.2.4 Interim Year System
Interim year plans are developed during a reappra isal of a transporta- tion plan to formulate a staged construct ion plan . The development of interim year plans should be coordinated with the Project Priorities
Office. The interim year networks should also be used as an aid in the determination of design traffic.
1.3 BASE MAPS
The FDOT urban area maps (at a scale of 1 inch to 2,000 feet) should serve as the source for developing networks whenever possible. In large study areas with much sparsely developed land, networks developed for the rural area may be done on maps with a scale of one inch to one mile.
These maps will have to be supplemented by maps photographically enlarged to a scale of one inch to 400 feet if densely developed urban areas are to be accurately assessed. The FDOT county maps (scale of 1 inch to 1 mile) will have to be used if the urban area maps do not cover the en- tire study area. The urban area and county maps are recommended because they were drawn and are peri odically updated from aerial photographs.
To support this procedure, FDOT will have to modify its urban area mapping effort. FDOT urban area maps (at a scale of 1 inch to 2,000 feet) will have to be expanded to cover the entire transportation study area. This can be done by enlarging the county maps. Furthermore, a new set of maps at a scale of 1 inch to 400 feet will have to be made for all densely developed areas.
3 1.5 DATA PROCESSING
The procedures have been written for use on FDOT's IBM 370 computer. All current highway networks will be stored on disk; computer cards will not be used. All computer job submissions will be done through time sharing operations (TSO).
All link data files that are being developed or are frequently used should be stored on-line (3350 disk). The link data files for the needs plan, adopted plan, existing plan, and interim year plan should always be stored on-line. Files that are current but infrequently used should be stored off-line (3330 disk).
5 2. FORMULATION OF HIGHWAY NETWORKS
This chapter deals with the basic definition of a highway network and a system of traffic analysis zones (TAZ). It will explain which roads should appear on the highway network, how TAZ's should be formed, how to develop, code, map, and check network data, and how to ensure the com- patibility of zones and networks (Figure 2-l). There are three principal occasions upon which this chapter should be referred to. The first and most obvious is when a completely new model is to be developed; the second is when a model is being reevaluated at the beginning of a plan update; and the third is when a model is being examined and modified to conform with FDOT's standard procedures.
Even though this report explai ns in detail the development of a highway
network, several publications would serve as supplementary references:
. PlanpaclBackpac Gene ral Information by the Federal High-
way Administration, April, 1977.
. Traffic Assignment by the Federal Highway Administration,
August, 1973.
. UTPS User's Guide by the Federal Highway Administration
and the Urban Mass Transportation Administration.
. Technical memoranda by the Florida Department of Transpor-
tation.
2.1 IDENTIFY THE STUDY AREA AND DIVIDE THE AREA INTO PLATES
The first step in formulating a highway network is to identify the study
area and determine its boundaries. This should be done carefully because
it will establish the basis for the entire travel demand modeling process.
6 FIGURE 2 - I NETWORK DEVELOPMENT FLOW CHAf?T
DATA BASE
BASE MAPS AERIAL PHOTOS CENSUS MAPS FACILITY TYPE MAPS POLITICAL MAPS LANE MAPS TOPOGRAPHICAL MAPS COUNT MAPS LAND USE MAPS SOCIOECONOMIC DATA MAJOR GENERATOR MAPS
JDENJJFY - DJVIDE _ DETERMINE - ESTABLISH - STUDY AREA’ INTO PLATES FACILITY TYPES TAZ’s
cI I
DRAW MYLAR LOCATE CONNECT LOCATE - CENTROIDS NETWORK MAP NODES TO NETWORK - CENTROIDS I I I t
DRAW MYLAR
CODE I NETWORK
t
INSERT INSERT TOLL LINKS 7 LANE NUMBERS FACILITY TYPES AREA TYPES 1- . COORDINATE DIGITIZE PLOT SCREENLI-NESCUTLINES NETWORK NETWORK DISTRICTS COUNTS l-5 CONSTRUCTION CODES The study area will be jointly defined by the Bureau of Urbanized Area
Systems Planning (BUASP) and the MPO, with the approval of the Federal
Highway Administration.
The network map should be divided into sections (or "plates"). These
plates will be used for drafting the producible mylar maps, computer
plotting, and node numbering. The following mapping scheme is suggested.
The rules are not rigid, and should work well for all but the largest ur- ban areas. If it is decided to depart from the guidelines, an orderly and systematic procedure should be established and documented.
Input
1. Base maps (urban area maps at a scale of 1 inch to 2,000 feet and
county maps at a scale of 1 inch to 1 mile).
2. Maps of census tracts.
3. Maps showing political boundaries and the area under the MPO's juris-
diction.
4. Maps of existing and future land use.
5. Knowledge of development patterns and potential for development,
especially from the MPO's staff.
output
1. Sketch of the study area.
2. Identification of information needed for mapping.
8 Method
1. Obtain blue-line copies of the base maps covering all areas that
might be included in the study area.
2. Obtain maps showing census tracts, political boundaries, land use,
and the area under the MPO's jurisdiction.
3. Sketch the study area on the urban area maps and county maps. The
study area should cover all areas under the MPO's jurisdiction. It
should conform with the political boundaries of cities and counties
and the boundaries of census tracts (or enumeration districts).
It should include all areas expected to be urban by the target year
of the study. Local planners with a knowledge of development patterns
should be involved in this process.
4. If the developed portion of the study area is larger than that covered
by the urban area maps at a scale of one inch to 2,000 feet, an expan-
sion of the urban area maps should be requested.
5. In very sparsely developed land, all mapping, including zone maps
and network maps, should be done at a scale of one inch to one mile.
At this time, it should be decided which parts of the study area will
be mapped at this scale and which will be mapped at a scale of one
inch to 2,000 feet, so that the mapping work described in the follow-
ing steps will be done at the correct scale.
6. Divide the study area into plates (see1Figure 2-2) so that:
. The study area can be displayed on a single 36-inch-by-44-inch
map at a scale of one inch to one mile.
9 FIGURE 2-2 NETWORK PLATE COVERAGE
42 miles
f/afe of scale / = I mile 15.9 miles
Plafe of scafe - / ‘I= 400:
Piafe of scale I”= 2,oool
Plate at scale I ‘I= 2,000'
Notes: AN plafes are 36';(44" I 'I = / mile plate should be used for fhe undeveloped areas / ‘I = 2,000’ plafes should be used for developed areas I ‘I= 400’ plafes should be used for the cenfroi business disfrict inset . All developed areas can be displayed on a series of 36-inch-by-
44 inch plates at a scale of one inch to 2,000 feet.
. The primary orientation of the-plates is north-south-east-
west. The format should be horizontal (i.e., the long
dimension of the map should run west to east).
. There is a one-inch border, reducing the usable size of
the plate to 42 inches by 34 inches. At a scale of one inch
to 2,000 feet, each plate will cover an area of15.9 miles
by 12.9 miles.
. The study area is covered by the fewest number of plates
possible.
7. Establish inset plates for densely developed urban areas so that:
. All areas where the fineness of the network makes the scale
of one inch to 2,000 feet inadequate are covered by plates
with dimensions of 44 inches by 36 inches and with a scale
of one inch to 400 feet. The maps at this scale for these
areas should be requested at this time.
. The primary orientation is north-south-east-west (i.e., not
skewed) in the horizontal format (i.e., the long distance is
east-west).
. The number of inset plates is as low as possible.
. Each inset plate lies completely with a single larger plate at
a scale of one inch to 2,000 feet whenever possible.
11 2.2 DETERMINE TYPES OF FACILITIES
All roadways within the study area should be classified according to type (Table 2-l). The primary responsibility for this task rests with the BUASP staff; the responsibility for data input and review will be assigned to the District Office and MPO staff. The results of this procedure will be used to identify and code the highway network and the
TAZ system. The facility type will also influence the capacity and speed of the roadway as it is represented in the model.
Input
1. Study area maps.
2. Maps of existing functional classifications on facility types.
3. Maps of existing lanes.
4. Traffic count maps.
Outout
1. Color-coded map of facility types.
2. Vellum map plates of preliminary highway network.
Method
1. Using all available data describing the street system such as
functional classification maps (facility type and functional classi-
fication are very similar, lane maps, and traffic count data, de-
termine the type of all roads within the study area. Facility types
are defined in Table 2-l. The facility types should be color-coded,
using a marker or pen, on base maps of the study area at two different
scales: one inch to 2,000 feet and one inch to one mile.
12 TABLE 2-l
DEFINITIONS OF FACILITY TYPE
Type of Facility Definition
Freeway A facility with full control of access to give preference to through traffic ( i.e., interstate and turnpike). Color code red.
Divided Arterial and A facility with a painted area wide Expressway enough to protect a left-turning vehi- cle, or with barrier or median (raised or depressed) separating opposing traf- fic flows, carrying most of the long trips made within and through an urban area, emphasizing traffic movement rather than land access, and carrying higher volumes than any facility except freeways. Expressways have some grade- separated intersections, fewer signals per mile than arterials, and some front- age roads. Color code green.
Undivided Arterials Similar to a divided arterial, except no painted area or physical barrier separ- ates opposing traffic flows. Generally has more signals per mile and fewer frontage roads, serves fewer through trips, and serves more land access than divided arterials. Color code blue.
Collector Street that “collects” traffic from local streets in neighborhoods and chan- nels it into the arterial system. A small amount of through traffic may be carried on collector streets, but the system primarily provides access to abutt- ing land by carrying local traffic between or within residential neighborhoods and commercial areas, or to roadways with more capacity. Color code yellow.
Centroid Connectors Local streets will be represented by cen- troid connectors and should not be iden- tified here.
One-Way Streets Any facility on which traffic may move in one direction only.
Source: Florida Department of Transportation.
13 2. Overlay the facility type map with vellum. The plate structure
identified in the previous section should be followed. Carefully
trace all major one-way streets, undivided arterials, divided ar-
terials, expressways, and freeways onto the vellum.
One of the most difficult decisions in the process of defining a network will be to determine which collectors will be included. Collectors should be used to fill in the network as follows:
. Include all streets that are protected from cross-traffic
by stop signs or signals.
l Include enough link segments to achieve continuity within
the network. This means that segments of collectors, which
in combination with other facilities would form a continuous
street, should be included in the network.
. Consider all links that carry more than 1,000 vehicles per
day.
The resulting vellum tracing is the preliminary blighway network map.
2.3 ESTABLISH THE TRAFFIC ANALYSIS ZONES
The TAZ system will be the basis for all data co1 lection and forecast-
ing throughout the study. TAZ's must be formed carefully to ensure
compatibility between zones and networks and to ease the collection and
manipulation of data.
I nout
1. Blue-line prints of the study area at the following scales: one
inch to 2,000 feet, one inch to 400 feet, and one inch to one mile.
14 2. Maps of census tracts (or enumeration districts).
3. Preliminary highway network map on vellum.
4. Maps showing physical barriers.
5. Maps of existing and future land use, especially maps that show
future population and employment densities.
6. Maps showing major travel generators.
Outout
1. TAZ work map on vellum.
Method
1. Draw census boundaries on blue-line prints of the urban area base
maps (the urban area maps at scales of 1 inch to 2,000 feet and 1
inch to 1 mile). In urban areas, the boundaries will be census
tract boundaries; outside of the urban areas, enumeration districts
will be used.
2. Draw all political boundaries on the blue-line maps. Except when
political boundaries have recently been changed, all political
boundaries will also be census boundaries. Each political unit
(city or county) should be composed of a number of census units
(tracts or enumeration districts). No census unit should be split
by a political boundary.
15 3. Overlay the blue-line census maps with the preliminary highway net-
work maps. Place a vellum sheet over these two maps. The new over-
lay will serve as the TAZ work map. Transfer the census boundaries
onto the new vellum overlay. TAZ's will be formed by subdividing
the census tracts or enumeration districts. In the unusual case of
a census unit split by a political boundary, it is best to use the
political boundary rather than the census boundary.
4. In genera 1, the highway network wi 11 form the remaining TAZ boundaries.
Physical barriers that restrict travel (rivers, canals, lakes, etc.)
should also be boundaries. Subdivide the census tracts or enumeration
districts, using the highway network and physical barriers as additional
TAZ boundaries; trace these boundaries onto the vellum overlay.
5. Review the preliminary zone map and make adjustments according to the
following guidelines:
. It becomes more difficult to collect, disaggregate, and fore-
cast socioeconomic data as the number of TAZ's increases.
Furthermore, computer time requirements increase geometrically
with the number of TAZ's.
. Land use within a zone should be homogeneous whenever possi-
ble.
. As many TAZ's as possible should have between 10,000 and
20,000 daily vehicle trip ends in the target year. Rough
trip generation rates relating the number of vehicle trip
ends to total population and total employment could be used.
A very rough estimate of vehicle trip ends for a TAZ can be
made upon application of the following equation:
16 TE = 2.4 (POP) + 5.5 (TEMP)
where:
. TE = vehicle trip ends;
. POP = residential population; and
. TEMP = total place-of-work employment.
The number of trips should be estimated using target year
population and employment forecasts. A TAZ with too few trip
ends will not cause traffic assignment problems, and a TAZ
with too many trip ends will cause such problems, especially
if the highway network that bounds the TAZ has a low traffic-
carrying capacity.
There should be roughly ten highway links (including centroid
connectors) per zone. A system consisting of square zones, each
having four centroid connectors, would have eight links per zone
(Figure 2-3). In a practical situation where the zones are not
square and there are extra nodes for matchlines and plotting, ten links per zone is a reasonable estimate.
If it is necessary to make some TAZ's larger than the areas delimited by the highway network, zones near collectors, rather than arterials and freeways, should be enlarged. In other words, it is more desirable to split a TAZ with a collector than to split one with a facility of higher type.
17 FIGURE 2 -3 LINKS PER ZONE RELATIONSHIPS
NUMBER OF LINKS CENTROID CONNECTORS PER ZONE * 0 2
I %I 4 I 4 2 El
2 6
/ 3 5 6 I) Q 3 7 2 4’ 7 E3
4 8
*IT CAN BE PROVEN THAT IN A SQUARE REGION CONSISTING OF UNIFORM SQUARE ZONES, THE RATIO OF INTERNAL LINKS ( LINKS WHICH DO NOT FORM PART OF THE REGION'S BOUNDARY ) TO ZONES APPROACHES TWO AS THE NUMBER OF ZONES APPROACHES INFINITY. . Ideally, TAZ's should be in the shape of regular polygons.
Many times they will not be, but extremely elongated shapes and
"gerrymandering" should be avoided. In general, zones located
near the CBD will be smaller than outlying zones.
. In some cases it will be useful to delete or add certain collec-
tors to improve the compatibility of zones and networks. Addi-
tion of TAZ's and addition and deletion of links is the mechanism
used to achieve compatibility.
6. The vellum overlay will be used to draft the formal TAZ maps for the
study. Therefore, it must be neat and accurate.
2.4 LOCATE THE CENTROIDS
The centroid of a TAZ should be at the center of the trip ends for that
TAZ. In a mathematical sense, if each trip end were given the weight of one, the centroid would be the TAZ's trip-end-based center of gravity or
"balance point." The location of the center of gravity will shift every time a change is made in the socioeconomic data, and hence the number and location of trip ends. For the purpose of travel modeling, the loca- tion of a centroid is fixed unless significant changes in the land use pattern of the zone occur.
Input
1. Highway network maps.
2. TAZ map.
3. Land use map.
4. Major generator map.
5. Aerial photographs.
6. Knowledge of the study area. 19 Out!3ut
1. Highway network maps showing centroids.
2. TAZ map showing centroids.
Method
1. Using the land use maps, major generator map, aerial photographs,
and any other data available, locate a centroid for each TAZ and
mark it on the TAZ map. Use your judgment to locate centroids; no
mathematical process is needed. The actual location of a centroid
connector is determined by the time and distance assigned to its
centroid connectors.
2. Transfer the TAZ centroid locations to the highway network map.
2.5 CONNECT CENTROIDS TO THE HIGHWAY NETWORK
Centroid connectors represent the local streets that connect trip origins and destinations to the highway network. Centroid connectors are idealized representations of the local street system and do not represent specific streets.
Input
1. Highway network maps with centroids.
2. Map of facility types.
3. Aerial photographs and/or detailed maps showing physical features.
output
1. Highway network maps with centroid connectors.
20 Method
1. Examine the aerial photographs and maps to determine where each zone
has access to the highway network.
2. Draw centroid connectors between the centroids and the highway net-
work, using dashed lines, according to the following rules:
. Each centroid must have at least one and no more than four
centroid connectors.
. Centroid connectors should connect with collectors or the
lowest type of facility available. They should never connect
directly with freeways, and should connect with divided arterials
only when there is no alternative means of access.
. Centroids should be connected in as many directions as possi-
ble (with a maximum of four allowed). However, care should
be taken to avoid traversing physical barriers or connecting
a centroid with the highway network if access does not exist
or is prohibited. In addition, a centroid should not be con-
nected to the same facility at more than one location.
. Future year networks should have a centroid connector system
that is different from the base year system if access conditions
change.
2.6 LOCATE AND DEFINE NODES
A highway node marks the end of each link. It is the point where two to four links are joined, and it usually represents an intersection or a cen- troid connection. The process of defining nodes is important because it defines many of the details of the highway network.
21 Input
1. Highway network map.
2. Map of facility types.
3. Aerial photographs or a detailed street map.
output
1. Highway network map with nodes added.
Method
1. Draw nodes on the highway network map as shaded dots. In general,
nodes should be placed at every intersection. The coding conventions
listed below should be followed:
. A node should be placed at every intersection where traff ic
interchange occurs.
. A node can have no more than four legs. If an intersecti on
has more than four legs, a dummy node and link must be in-
serted as indicated in Figure 2-4. The network map should
be modified to show the dummy nodes and links where they are
coded. The word "dummy" should be placed on the link to show
the true location of the dummy node.
. Freeways should be coded as two-way links. This convention
is less complicated than coding the freeway as one-way links.
In general, freeway ramps should not be coded. Ramp volumes
will appear as turning volumes at nodes representing inter-
changes. The UROAD turn prohibitors can be used to represent
partial interchanges. Exceptions to this rule will be the
following cases:
22 NGURE 2 - 4 DUMMY NODES AND LINKS
ACTUAL FIVE-LEGGED INTERSECTION
zero time and distance /Ink
SIMULATED FIVE - LEGGED INTERSECTION - The interchange is highly complex and a single node
will be more confusing than explicit coding of the ramps.
- A ramp is highly overloaded, but the mainline volume is
not at capacity and capacity restraint is needed to re-
flect the actual diversion of traffic.
. Frontage roads should be coded if they have a significant traffic-
carrying capacity and serve a higher function than that of a local
street.
. All one-way streets should be marked with arrows indicating
the direction of travel.
. Additional plotting nodes should be added so that curved
roads can be closely approximated by a series of straight
line segments as plotted by CALCOMP. This is important not
only from an aesthetic standpoint, but because link distances
will be measured along the straight line segments rather than
the actual curvilinear distance.
2.7 DRAW MYLAR HIGHWAY NETWORK MAPS
Mylar highway network maps should be drawn in conformance with the pre- viously established map plates.
Input
1. Highway network maps.
2. Mylar drafting film with dimensions of 36 by 44 inches.
output
1. Mylar highway network maps.
2. Cover sheet for network map series.
24 Method
1. Trace the highway network onto reproducible mylar maps. Each mylar
sheet should be the standard size (36 x 44 inches) and should repre-
sent a plate. The following conventions should be used:
. Matchlines should be established at the junction of plates,
and nodes should be inserted at points where links cross
matchlines.
. A one-inch border should be drafted around each map, making
the effective area of the map 34 by 42 inches.
. Nodes should be drawn as solid dots. A 3/16-inch circle
template is suggested.
. Centroids should be drawn as unshaded circles with a diameter
of 3/16 of an inch.
. Links should be drawn as solid lines (a number 5 pen is
suggested).
. Centroid connectors should be drawn as broken lines.
. All work should be first drawn in pencil and then carefully
inked.
. The plate borders should serve as matchlines, eliminating the
need for additional nodes at each plate border.
2. A legend should be placed in the one-inch border, as shown in Figure
2-5. This legend should include:
. The name of the study.
25 FIGURE 2-5 NETWORK MAP LEGEND
Tmpa Urban Area Transportation Study Adopted Plan PJate 3of 6 Standard Highway Network Map IN = 2000’ . The phrase "Standard Highway Network Map."
. The name of the network (existing-plus-committed, adopted
plan, etc.);
. Scale.
. Plate number.
Other identifying information will not be required if the maps are
drawn in conformance with the standard procedures described herein.
3. A cover sheet 36 by 44 inches should be made for the series of net-
work map plates. It should display the coverage of the plates
comprising the study, similar to that showed in Figure 2-2. The
map shown on the cover sheet should be drawn or copied from the
county maps with a scale of one inch to one mile (a different scale
would be appropriate if the entire study area will not fit on a
single sheet at this scale). The coverage map should show the name
of the study, map scales, plate coverage, plate numbers, and the zone
numbers contained on each plate.
2.8 DRAW MYLAR TAZ MAPS
Mylar TAZ maps should be drawn so that they overlay the network maps. The
TAZ maps should be drawn to conform with the plates and scales of the standard highway network map. These maps will be useful throughout cali- bration of the model and development of the long-range transportation plan.
Input
1. TAZ work map on vellum.
2. Mylar drafting material with dimensions of 34 by 46 inches.
3. Blue-line prints of highway network inset plates at a scale of one
inch to 400 feet. 27 output
1. Mylar TAZ maps.
Method
1. Outline the area covered by each highway network plate on the vellum
TAZ map.
2. Overlay the area covered by each plate with a mylar sheet and
trace the TAZ boundaries onto the mylar in pencil. In areas where
the network is displayed on inset plates at a scale of one inch
to 400 feet, the TAZ boundaries should first be established on
the blue-line copies of the highway network inset plates and then
traced in pencil onto the corresponding mylars.
3. Ink one-inch borders on the mylar TAZ maps.
4. Ink the TAZ boundaries.
5. Label each plate with the following information (see Figure 2-4):
. Name of study.
. The phrase "Standard Zone Map."
. Scale.
. Plate number.
2.9 NUMBER THE NODES
TAZ's and highway nodes should be numbered according to a systematic scheme. Any number of schemes could be devised, but the following scheme is suggested.
Input
1. Mylar TAZ maps.
2. Mylar highway network maps. 28 output
1. Mylar TAZ maps with zone numbers.
2. Mylar highway network maps with centroid and node numbers.
Method
1. Number the TAZ and highway network map plates. The plate containing
the CBD should be numbered 1, and the plates should be numbered in
order moving away from the CBD. Plates should receive consecutive
integers as identifying numbers.
2. Centroids (TAZ'S) should be numbered. The numbers should be inked
on the highway network map plates and on the TAZ map plates (centroid
numbers must be consecutive integers beginning with number 1). The
numbering should begin on plate 1. All centroids on the first plate
should be numbered before the second plate is numbered, and so on.
All possible node numbers should be listed and numbers should be
marked off as they are used. This will help eliminate duplicate
numbers and allow early identification of unused numbers. After
all of the centroids have been numbered, skip a number of centroid
numbers equal to five percent of the number of TAZ's before number-
ing the external stations (external stations are actually centroids).
The extra centroid numbers will be used if it becomes necessary in
the future to split zones because of an unusually large amount of
growth. External stations (nodes on the study area boundary through
which autos may enter and leave the study area) should then be
numbered.
3. Nodes should be numbered. Node numbers should begin with 1,001
(or a higher number if there are more than 1,000 TAZ's and external
stations). The highest allowable node number is 8,191. The most 29 significant digit (thousands) should be the plate number. Each plate should be divided into ten bands (Figure 2-6), numbered 0 through 9, with the band number becoming the digit in the hundreds column. Bands should be numbered from the bottom to the top of the plate. Band widths should be varied so that each contains approxi- mately the same number of nodes. Tick marks delineating the bands should be placed on the right and left border lines, and band numbers should be drawn in the right border area. The right two digits should indicate the position in the band; they should range from 1 to 99, beginning at the left edge of the map and increasing as they approach the right edge. The nodes should not be numbered consecutively; gaps should be left so that nodes can be added in the future without depart- ing from the geographical numbering scheme.
Node and centroid numbers must be carefully placed and lettered.
The former should be placed so that the numbers point to the node
(Figure 2-7). In such a case, a line connecting the center of each numeral would pass through the center of the node. Node numbers can be lettered by hand or Leroyed (a 140 CL template would be appro- priate). Hand lettering must be skillfully done to ensure uniform size and a legible style (closed fours and flowing sixes and nines must be used). Machine lettering (such as the Kroy type) in which an adhesive is used to affix the number to the map should not be employed except on work maps that will be photographed because the adhesive may not last.
30 FIGURE 2- 6 NODE NUMBERING
Band number
Tick marks delineating the bands
Band lines are NOT to be drawn on the mylar
EXAMPLE NODE
I
-..- .._.___ __._____I.______I I I
--.-. .____-_ ..--.
I I --______.I_~~ ~______
I I I position of numbers in the bond position 72 I 99 FIGURE 2 - 7 NODE NUMBER PLACEMENT AND LETTERING 2.10 BEGIN NETWORK CODING
In the initial network coding, highway links, as defined by node numbers, and facility types will be placed in a computer file. Other network data will be added in later steps.
Input
1. Maps of facility types.
2. Mylar highway network maps.
output
1. Initial highway network link file on computer disk.
2. Computer listing of the highway network link file.
Method
1. The following data should be coded in the initial effort:
. A-node in columns 3 through 6.
. B-node in columns 9 through 12.
. S in column 18.
. X or blank in column 41.
. Type of facility in column 66.
All data should be right justified and there should be no leading
zeros.
2. Code all network links. Coding should begin with centroid connectors,
but all other links can be coded in any order desired. Except for
one-way links, the A-node should always be the node with the lowest
number. In the case of one-way links, the link should be coded in
the direction of permitted traffic flow.
33 3. Code one-way and two-way indicators. In all cases, S should appear
in column 18. An X should be placed in column 41 in the case of two-
way links, and left blank in the case of one-way links.
4. In column 66, code the facility types, as determined from the facility
type maps used to develop the network. The codes are as follows:
. 1 - Freeway.
. 2 - Divided arterial.
. 3 - Undivided arterial.
. 4 - Collector.
. 5 - Centroid connector.
. 6 - One-way arterial.
5. Keypunch these data and place them on an on-line disk file, using
the standard conventions for naming data sets (see Chapter 5). The
links should then be sorted in ascending order; the primary sorting
should occur on the A-node and the secondary sorting on the B-node.
The %SORT procedure should be used. A "hard copy" list of the file
should then be produced by entering the PRINTOFF command.
2.11 INSERT TOLL LINKS AND EXTERNAL STATION CONNECTORS
A toll link is a zero-distance link in the network that can be assigned a delay time and a toll value (which in turn is converted to a time). The time, or "impedence," on the toll links is used in the pathfinding and skimming procedures of the model. Toll links have a "$" in column 15 and toll codes in columns 16 and 17. Toll codes can range from 1 through 20, and their use is explained in the UROAD documentation.
34 External station connectors are zero-distance dummy links that should be inserted between facilities that cross the boundary of the study area and external stations. These connectors prevent some transportation plan- ning programs from considering facilities that cross study area boundaries as centroid connectors.
Input
1. Mylar highway network maps.
2. Toll link locations and codes.
output
1. Mylar highway network maps, including toll links.
2. Updated highway network file on computer disk.
3. Computer listing of the file.
Method
1. Insert nodes defining each toll link in the appropriate location on
the mylar highway network maps. Number the nodes in accordance with
the previously described scheme. Since the toll links are zero-
distance 1inks and appear on the mylar for purposes of display only,
they should be drawn as short as possible, while still allowing node
numbers to be clearly displayed. The toll links should be labeled
"TOLL" and an arrow should show the true location of the dummy node
(Figure 2-8).
2. Correct all previously coded links that were altered by the insertion
of the toll links. These changes can be made directly on the link
file by means of TSO.
35 FIGURE 2- 8 INSERTION OF A TOLL LINK
TOLL BOOTH
DELETE LINKt 5104 5108 t CC--3 CC:18 CC--41 CC66
ADD LINKS, 5104 5106 s x 3
5106 5107 $12 s x 3
5107 5108 cc-15rf cc:17 sx3 3. Code the toll links and insert them into the link file using TSO.
Toll links are coded in the same way as other links, except a "$" is
placed in column 15 and the toll code is placed in columns 16 and 17.
4. External station connector dummy links (coded as facility type 5)
should be inserted between external stations and facilities crossing
the boundary of the study area. These links will have zero distance.
An additional node should be coded and numbered near the external
station, and an arrow should be placed on the network map so that
the added node is given the same coordinates as the external station.
5. Sort and list the link file, as explained in section 2.10.
2.12 DIGITIZE THE NETWORK
The highway network must be digitized; that is, each node and centroid must be assigned X and Y coordinates. Digitization will allow the network to be plotted by applying computer plotting techniques, thereby easing the
"debugging," analysis, and evaluation of the network. Accuracy in this step is important because highway distances will be calculated from the coordinates of the nodes.
Input
1. Mylar highway network maps.
output
1. Highway network coordinate file.
Method
1. A rectangular coordinate system should be established so that the
network can be digitized. The origin should be placed in the lower
37 left corner so that the entire study area lies within the coordinate
geometry first quadrant. The coordinate system should be aligned in
true north-south and east-west directions so that the coordinates
can later be referenced to the state plain coordinate system.
2. Each centroid and node should be assigned coordinates. The X coor-
dinate should be the number of miles east of the origin, and the Y
coordinate the number of miles north of the origin, each measured
to the nearest hundredth of a mile. FDOT's digitization equipment
should be employed to measure coordinates from the network maps.
To align each plate in the digitizing machine, a point with known
coordinates and a true direction must be established on each plate.
Coordinate cards (which will be keypunched by the digitization
equipment) must be coded in the following format:
. Node number in columns 1 through 6, 16 format.
. X coordinate (miles in columns 7 through 14, 18 format, with
an implied decimal point between columns 12 and 13.
. Y coordinate (miles) in columns 15 through 22, 18 format,
with an implied decimal point between columns 20 and 21.
Using the above format, an X coordinate of 2,174 would represent
a point 21.74 miles east of the origin.
2. Place the coord inates on an on-l ine d isk file, using the standard
conventions for naming data sets (see Chapter 5). This must be done
in the batch mode with punched cards and the program BPRCOPY to trans-
fer the cards to disk. After transfer of the file to disk, it should
38 be sorted in ascending order of the nodes using the %SORT procedure.
The PRINTOFF command should then be entered to produce a "hard copy"
list of the coordinate file.
2.13 PLOT THE NETWORK
The highway network should be plotted at the same scale as the mylar high- way network maps. Errors in networks and coordinates can then be easily identified by overlaying the plots on the mylar base maps.
Input
1. Highway network link file.
2. Coordinate file.
3. Mylar highway network maps (or prints).
output
1. Highway network plots overlaying the mylar maps at the correct scale.
2. Identification of network errors.
Method
1. Build an unloaded historical record in the following steps:
. Place the coordinate and link files in FDOT's XYDIST program,
which uses the coordinates to calculate link distances and
inserts the distances on a new link file.
. Use the XHNET UTPS procedure to build an unloaded historical
record with coordinates.
2. Calculate the appropriate scale and coordinate ranges for each plate,
which should correspond to the mylar network map plates.
39 3. Use the %PLOT routines to plot the network according to the follow-
ing specifications:
. As mentioned earlier, set up plates that will directly over-
lay the mylar base maps. The data that will be needed to set
up each plate include the maximum and minimum X and Y coordinate
values, the scale factors (0.01 for a scale of 1 inch to 1 mile,
0.0264 for a scale of 1 inch to 2,000 feet, and 0.1320 for a
scale of 1 inch to 400 feet), and the maximum and minimum X and
Y coordinate values of the area of no annotation. It is suggested
that areas on a plate with a scale of one inch to 2,000 feet
that are covered by an inset plate at a scale of one.inch to
400 feet not be annotated; the same recommendation is made for
the areas on a plate with a scale of one inch to one mile that
are covered by an inset plate at a scale of one inch to 2,000
feet. These data should be carefully determined and saved in
the PLOTMEM partitioned data set member (DSN = D552093l.GEPLOT.
DATA) for the study for use in subsequent plotting application
(see the FDOT Standard Model Tech Memos for further documentation).
. Specify two plotting colors; black for highway links and red for
centroid connectors.
. Annotate all node and centroid numbers.
4. Compare the plots with the mylar base highway network maps. Note all
errors and correct the link and/or coordinate files as appropriate.
The only difference between the highway network map and the plot will
be at dummy links; the links will be plotted as they appear on the
ground rather than the way they are represented on the highway network
maP* 40 5. Execute the BUILDHR CLIST procedure to build the historical record,
using the PLANPAC program BUILDHR. The purpose of this step is to
identify errors. BUILDHR will identify unconnected TAZ's and will
flag toll links as errors. These messages will not be produced by
the %HNET UTPS procedure.
6. Repeat the procedure until all errors have been eliminated.
2.14 DRAFT THE NUMBER OF LANES AND TYPE OF FACILITY ON THE MYLAR HIGH- WAY NETWORK MAP
All network data should be inked on the mylar highway network maps. These data will be coded from these maps, and the maps will serve as the permanent record of these data.
Input
1. Color-coded work map of facility types.
2. An inventory of the number of lanes on each highway (a map, aerial
photograph, or other list describing the street system).
3. Mylar highway network maps and a blue-line copy.
Outout
1. Mylar highway network map with data on lanes and facility types.
2. Color-coded blue-line maps of facility types.
Method
1. Determine the type of facility (refer to the color-coded facility
type map from section 2.2) and the number of lanes on each highway
link, which should be the sum of the number of lanes in both direc-
tions. The following abbreviations should be used:
41 . FWY - Freeway.
. DA - Divided Arterial.
. UA - Undivided Arterial.
. COL - Collector.
. Centroid connector - not needed.
. ow - One-Way Arterial.
2. Ink the lane and facility type data onto the mylar. These data
should be carefully hand lettered or Leroyed (a 120 CL template is
suggested). The designation should first show the number of lanes
and then the facility type (for example, 6-DA indicates a six-lane
divided arterial).
3. Using pens or markers, color-code the blue-line maps according to
type of facility. Freeways and one-way streets should be shown in
red, divided arterials and expressways in green, undivided arterials
in blue, and collectors in black. These maps will be used in debugging
networks.
2.15 ESTABLISH AREA TYPES
Each link in the highway network must be assigned an area type that describes the characteristics of the surrounding land. Area types should be carefully specified because they, along with type of facility and number of lanes, determine the link's speed and capacity.
Input
1. Mylar highway network maps.
2. Blue-line print of the highway network map.
3. Existing (base year) land use maps.
42 output
1. Mylar highway network maps with area type designations.
2. Color-coded maps showing area types.
Method
1. Examine the land use maps and classify each land use as one of the
area types defined in Table 2-2.
2. Sketch the boundaries of each area type on the blue-line print of
the network map. To be consistent with the definitions in Table 2-2,
outlying business districts (OBD) should be wholly contained within
rural or residential areas. The OBD is the only area type that can
be facil ity-specific; that is, a roadway with strip commercial de-
velopment on both sides in the midst of a residential area would be
considered OBD. There should be only one closed CBD area unless the
study area contains more than one central city. All fringe areas
must abut the CBD. Figure 2-9 illustrates some considerations that
pertain to area type.
3. Shade each area type on the blue-line maps with a different color.
These maps will serve as a reference for debugging networks.
4. Trace the area type boundaries onto the mylar network maps (it is
suggested that a 00 pen be used). The boundaries should be inked in
a thin dashed line. The following designations should be placed
on either side of the boundary lines to label the area types:
. CBD - Central business district (type 1).
. FRN - Fringe area (type 2).
. RES - Residential area (type 3).
. OBD - Outlying business district (type 4).
. RUR - Rural area (type 5).
43 TABLE 2-2
DEFINITIONS OF AREA TYPE
Type of Facility Definition
Central Business District (CBD) An area where the predominant land use is intense business activity. Charac- terized by large numbers of pedestrians, commercial vehicles, loadings of goods and people, a large demand for parking space, and a high degree of turnover in parking.
Fringe Area The portion of a municipality immediately outside the CBD. Exhibits a wide range of business activities (small businesses, light industry, warehousing, automobile service centers, and intermediate strip development, with some concentrated resi- dential areas). Traffic in these areas generally involves trips that do not have an origin or destination within the area. Less pedestrian traffic and lower parking turnover than in CBD. However, large parking areas serving the CBD might be present.
Residential Area An area within the influence of a munici- pality in which the predominant land use is residential development (small busi- nesses may be present). Characterized by few pedestrians and low parking turnover.
Outlying Business District An area within the influence of a munici- (OBD) pality that is normally separated by some distance from the CBD and its fringe area, but that has the intense activity charac- teristic of a central area. The principal land use is business, and there may be heavy traffic or through movements, caus- ing vehicles to operate at lower speeds than in fringe areas. Also characterized by large demand for parking and high turn- over, and moderate pedestrian traffic. This category does not include off-street shopping on one side of a street only. Moderate to heavy strip development on both sides of a street should be coded OBD.
Rural Area A sparsely developed area within the in- fluence of a municipality in which the pre- dominant land use is other than those de- scribed in the four preceding categories.
Source: Florida Department of Transportation. 44 FIGURE 2 -9 AREA TYPE EXAMPLE
\
\
---7 \
\
\
I I f / /
STUDY AREA ‘BOUWARY 5. Area type designations for future year networks should conform to the
land use plan for the year in question.
2.16 ESTABLISH SCREENLINE AND CUTLINE LOCATIONS
Screenlines and cutlines used in highway network analyses should be drawn on the mylar highway network maps to make coding easier and to form a perman- ent record.
Input
1. Mylar highway network maps.
2. Blue-line print of the network maps.
output
1. Mylar highway network maps with screenlines and cutlines.
2. Blue-line prints with screenlines and cutlines.
Method
1. Sketch screenlines and cutlines on the blue-line prints of the high-
way network maps. In general, screenlines should completely divide
the study area, beginning and ending at its boundary, and should follow
some physical barrier such as a river, canal, or railroad track to
minimize doulbe-crossings of the screenline. Cutlines are used to de-
termine traffic volumes in corridors and need only span major corridors.
A screenline can be divided into two or more cutlines if convenient,
or can be composed of two or more cutlines to minimize coding. In
most study areas, two screenlines (a north-south and an east-west one)
will suffice. A few more can be added if there are convenient physical
barriers. The study area boundary (cordon line) should be coded as a
46 cutline. Similarly, it is useful to draw a closed cutline around the
CBD. All major travel corridors should contain cutlines if travel in
the corridor could take place on more than one facility. Although
the number of cutlines will vary according to the characteristics of
the study area and street system, twelve is a good average.
2. Trace the screenlines and cutlines onto the mylar highway network
maps. They should be drawn in a line style that differentiates them
from area type boundaries. Screenline and cutline numbers, which
can range from 1 through 98, should be inked in at both ends of the
line on each map plate.
2.17 ESTABLISH DISTRICTS
Districts, or other analysis areas such as planning sectors, should be established and drawn on a blue-line copy of the mylar highway network maps. To avoid clutter, they should not be drawn on the mylars.
Inouts
1. Blue-line copy of the mylar TAZ maps.
2. Blue-line copy of the mylar highway network maps.
output
1. Blue-line highway network map with district boundaries.
2. Zone-district equivalency table.
Method
1. Using a colored marker, draw the district boundaries on the blue-
line TAZ map. Label the districts that can have numbers between
1 and 49. Districts should be composed of a number of TAZ's; dis-
trict boundaries should coincide with TAZ boundaries.
47 2. Construct an equivalency table, listing the TAZ's comprising each
district. This equivalency table will be useful in network analysis
and planning. In many cases, the district boundaries, which are also
TAZ boundaries, will be highway links. This means that when a dis-
trict number is assigned to a boundary link, the district number to
be assigned must be decided upon. The links should be assigned the
number of the district with the greatest access to the link. If
this cannot be determined, east-west links should be assigned the
north district number, while north-south links should be assigned
the east district number. In most instances, this is not a critical
decision and should not receive undue attention.
3. Trace the district boundaries onto the blue-line highway network
maP* This map will serve as a reference for network coding and de-
bugging.
2.18 POST TRAFFIC COUNTS
If the network is an existing year network, traffic counts should be posted on blue-line prints of the network maps. Counts could also be posted on a future year network to allow a future volumes and existing counts to be compared.
Input
1. Blue-line print of the network maps.
2. Validation year traffic counts.
output
1. Blue-line print of the network with posted traffic counts.
48 Method
1. Obtain traffic counts for as many highway links as possible in the
validation year.
2. Post them in their correct location on a print of the highway network
maps.
3. Refer to FDOT's Procedures Manual, Validation Procedures (forthcoming)
for possible revisions in the method used for obtaining up-to-date
traffic counts.
2.19 ESTABLISH CONSTRUCTION CODES
If the network is a future year network and the transportation study methodology is employing a network-based procedure to estimate con-
struction costs, construction codes should be placed on the network.
The methodology for assigning construction codes is beyond the scope of this paper, but will depend on the methodology of the individual
study until a standard FDOT procedure can be developed.
Input
1. A construction code procedure that assigns construction codes rang-
ing from 1 through 99 to specific types of construction.
2. Blue-line prints of the network maps.
3. Description of proposed highway improvement projects.
4. List of the link file.
output
1. Blue-line highway network map with construction codes.
2. List of highway links and construction codes.
49 Method
1. Identify each highway construction project and determine the con-
struction code describing it. Most construction code schemes will
associate a cost per mile of construction with each possible type
of construction. Types of construction are usually defined by the
characteristics of the old and new typical sections of the highway.
2. Write the construction codes on the list of the network file in
preparation for updating the file.
2.20 CODE NETWORK DATA
The network data established in sections 2.14 through 2.19 should be coded on the network list obtained in section 2.11. These data should then be entered into the highway network link file by means of TSO.
Input
1. Mylar highway network maps with the following data inked on the
maps:
. Number of lanes.
. Type of facility.
. Type of area.
. Screenlines and cutlines.
2. Blue-line highway network maps with the following data marked on
them:
. Districts or planning sectors.
. Traffic counts (existing year networks only).
. Construction codes (future year networks only).
3. Highway network link file.
50 4. List of the highway network link file.
output
1. Complete highway network link file.
2. List of the highway network link file.
Method
1. Code all link data on the list of the highway link file. It is
suggested that all data for each link be coded, in the order in
which the links are encountered on the list, to ensure that no
data items are omitted. It will be easier to accomplish this if
the list of the highway link file is double-spaced.
2. Using TSO, enter the link data into the highway network link file.
Care should be taken to enter the data in the correct columns (see
below):
. Traffic counts: columns 32 through 36.
. Number of lanes: column 37.
. Construction code (future year network): columns 53 through 54.
. Area type: column 68.
. Screenlines and cutlines: columns 69 through 70.
. District or sector: columns 71 through 72.
If the FDOT Traffic Count Telemetry System' is to be used to place counts on the link records, the count station number should be placed in columns
48 through 51, the count source code (rather than construction code) should be placed in columns 53 through 54, and the county code should be placed in columns 62 through 63. A four-column count date code should be placed in columns 77 through 80 as follows:
ISee FDOT's "UTP Tech Memo" discussing validation link card coding, March 28, 1980.
51 . Day number (l-7, Sunday-Saturday): column 77.
. Month number (1-12): columns 78 and 79.
. Year (last digit): column 80.
While entering these data, the operator should depress the "enter" key
at least once every five minutes to avoid being logged off by the system,
and the file should be "saved" periodically to minimize the amount of data that would be lost if the computer system should "crash." The complete
network link card format is shown in Table 2-3.
2.21 CODE TURN PROHIBITORS
Turn prohibitors should be coded at locations where specific turning movements are prohibited. The most common location for turn prohibitors will be at partial freeway interchanges and along arterials at which
access is controlled to some extent. Turn prohibitors should be noted
on the mylar highway network maps. Turn prohibitors are not part of the
highway network link file. They are included in the UROAD program con- trol cards. Turn penalties should not be coded.
Input
1. Mylar highway network maps.
2. Map or tabulation of prohibited turns.
output
1. Mylar highway network maps with arrows showing turn prohibitors.
2. A file of turn prohibitor trailer cards.
Method
1. Draw turn prohibitors (Figure Z-10) on the mylar highway network
maps. 52 FIGURE 2-/O TURN PROHIBITORS
PROHIBITED TURIVS : 200/- 2003 -2004 2005- 2003 - 2002 TABLE 2-3
NETWORK CODING SUMMARY
Columns Content Default
3-6 A node number None
9-12 B node number None
14-17 Link distance or "$xx" where xx is the toll class None 11 II 18 S None
19-21 Toll booth service time None
32-36 Two-way count 0
37 Two-way number of lanes (O-9) 9
41 "X" if the link is,two-way None
53-54 Construction code (O-99) 0
66 Type of facility (l-6) 5
68 Type of area (l-5) 5
69-70 Screenline (l-99) 99
71-72 District or sector (l-49) 49
48-51a Count station number None
53-54a Count source code (in place of construction code) 0
62-63a County code None
77-80a Count date code None
aThese columns must be used to use the FDOT Traffic Count Telemetry System (see FDOT UTP Tech Memo, Validation Link Card Coding, March 28, 1980).
Source: Florida Department of Transportation and Schimpeler.Corradino Associates.
54 2. Code the turn prohibitor cards. Three prohibitors can be coded
on each card according to the following format:
. "T" in column 1.
. First “from" node in columns 2 through 6.
. First intersection node in columns 7 through 11.
. First "to" node in columns 12 through 16.
. Second "from" node in columns 22 through 26.
. Second intersection node in columns 27 through 31.
. Second "to" node in columns 32 through 36.
. Third "from" node in columns 42 through 46.
. Third intersection node in columns 47 through 51.
. Third "to" node in columns 52 through 56.
3. Enter these data into the &DATA deck in all applications of
UROAD.
2.22 PLOT THE NETWORK DATA
The network data should be plotted to find errors. A series of four- color plots with various degrees of annotation will be developed. The
plots will be made at the same scale as the mylar highway network map
plates so that data items can be checked by overlaying the plots on
prints of the maps. The CALCOMP plotter, through the %PLOT procedures, will be used to create the plots (refer to FDOT's technical memos on the
standard model for complete documentation of the %PLOT procedure).
The XPLOT procedure uses the PLANPAC programs GEPREP and GEPLOT; the control cards are stored in partitioned data set members PREP (D5520931.
GEPREP.DATA) and PLOT (D552093l.GEPLOT.DATA ). The %PLOT procedure allows
55 the user to modify these members while executing the procedure. There is a PLOT member for each urban area and a PREP member for each type of plot (e.g., lanes, facility type, area type, district, and screenline).
Input
1. Blue-line prints of network maps with annotation, color coding,
and other symbols displaying the network data developed and coded
in the previous steps.
2. List of the highway network link file.
output
1. Computer plots displaying the highway network data.
2. A corrected and edited highway network link file.
3. An unloaded highway historical record.
Method
1. Rebuild the historical record using the %HNET UTPS procedure.
2. Use %PLOT to create a four-color, non-annotated set of plots dis-
playing types of facilities. The PLOT member should suppress all
annotation and the facility type PREP member should specify the
following colors:
. Red - freeways (type 1) and one-way arterials (type 6).
. Green - divided arterials and expressways (type 2).
. Blue - undivided arterials (type 3).
. Black - collectors (type 4).
56 The low node number in the PLOT member should be set equal to the first noncentroid node number to suppress the plotting of centroid connectors.
Compare the plots to the color-coded maps described in section 2.14 and note all errors on the list of the network link file.
3. Using %PLOT, create a four-color, non-annotated set of area type
plots. The PLOT member should suppress all annotation and the area
type PREP member should specify the following colors:
. Red - CBD (type 1) and rural (type 5).
. Green - residential (type 3).
. Blue - OBD (type 4).
. Black - fringe (type 2).
The low node number in the PLOT member should be set equal to the first noncentroid node number to suppress the plott ing of centroid connectors.
Compare the plots to the area type boundaries established .in section
2.15 and note all errors on the list of the network link file.
4. Using XPLOT, create a four-color, non-annotated set of plots dis-
playing the number of lanes in the A-B direction. The PLOT member
should suppress all annotation and the PREP member signifying number
of lanes should specify the following colors:
. Red - one lane.
. Green - two lanes.
. Blue - three lanes.
. Black - four or more lanes.
The low node numbers in the PLOT member should be set equal to the
first noncentroid node number to suppress the plotting of centroid
57 connectors. Compare the plot to the mylar highway network map,
checking the plotted colors with the number of lanes. Note all errors
on the list of the network link file.
5. Assign the color red, green, blue, or black to each district (or
sector) so that no districts with a common boundary are the same
color; using %PLOT, edit the district PREP member to assign these
colors to the districts. To do this, a temporary link file must
be created so that all red districts become district 1, all blue
districts become district 2, all green districts become district 3,
and all black districts become district 4. Edit the PLOT member to
suppress all annotation and plotting of centroid connectors. Com-
pare the plots to the district map that was drawn in section 2.17,
and note all errors on the list of the highway network link
file.
6. Plot screenline and cutline links using %PLOT. The screenline
PREP member should specify that screenlines numbered 1 through 98
should be plotted in red and screenline 99 (the default value
for no screenline coded) should be plotted in black. Edit the
PLOT member to suppress all annotation and plotting of centroid
connectors. The plots should be compared to the base highway network
maps, and any screenline and cutline errors should be noted on the
list of the highway network link file.
7. Using TSO, enter all network corrections into the computer. If
the corrections are few and uncomplicated, it will not be necessary
to replot the network data. However, if it is desired to repeat
any of the plots after network corrections have been made, %HNET
should be run again to rebuild the historical record.
58 8. Upon completion of this step, the network is ready for use in the
standard model.
59 3. COMPATIBILITY OF ZONES AND NETWORKS
3.1 GENERAL DISCUSSION
The network development procedures described in this report should pro- duce a highway network and TAZ system that are compatible. The methodology first established a highway network and then a TAZ system that would pro- duce a level of interzonal trips required for correct loading of a valida- tion network (e.g., replication of traffic counts).
Once a trip table, a TAZ system, and a network that produce correct link load i ngs have been established, the addition of links to the network will reduce the average link loading, while the deletion of links will increase the loading in both cases, the accuracy of the model will be de- creased. Similarly, if a TAZ is divided in two, some trips that were pre- viously intrazonal w i 11 become interzonal and will be loaded on the net- work, thereby increasing the average link load. The converse is also true; if two TAZ's are combined, the number of interzonal trips will be decreased, thereby reducing link loads. These examples show that there must be a balance between three elements: the trip table, the network, and the TAZ system. Checks on the compatibility of zones and networks should be made so that the models can be adjusted to achieve this balance.
Careful review of a plot of a validation highway assignment may reveal areas where improper loadings occur, usually because of a "point" loading at a centroid connector from a major generator. Such a situation might be corrected by adding additional centroid connectors, but if this is not a reasonable solution, the analyst should at least recognize this deficiency
60 when evaluating future year assignments. In some cases, these links should be eliminated from comparisons of volumes and counts, and/or screenlines and cutlines should be restructured to avoid these known problem areas.
3.2 TRIP GENERATION ANDDISTRIBUTION CONSIDERATIONS
As stated earlier, the trip table must be in balance with the TAZ system and the network. This means that the compatibility of zones and networks is dependent on the trip generation and distribution models.
Before screenlines and cutlines are checked, the procedures for building the trip table should be examined. If the model was calibrated with the benefit of a home-interview survey of origins and destinations, one of the first checks should be to compare the trip table as expanded from the sur- vey and assigned to the network with the ground counts on the network at screenlines. If the screenlines do not closely match even after errors such as multiple crossings of screenlines have been accounted for, it is usually assumed that the survey was underreported or overreported, and the trip table is modified to correct the error in the survey expansion rates.
The calibration of trip generation, distribution, modal split, auto occu- pancy, and assignment models can then proceed, assuming the number of trips being produced is appropriate for the fineness or coarseness of the highway network.
If the model is being validated to a new base year using trip generation rates and friction factors developed from an old survey (or borrowed from another urban area), this check cannot be made. This will likely result in a less accurate model, but the error will be minimized if the validation year network is of the same fineness or coarseness as the survey year net- work. For example, it is not reasonable to assume that a trip generation
61 and distribution model calibrated to build a trip table for a network con- taining only facilities classified as major arterials or higher would be suitable for a network that also contains a substantial number of collectors and local streets. If the survey year and validation year networks are of significantly different fineness or coarseness levels, the trip generation and distribution models will probably have to be adjusted, complicating the model development process. The other options would be to adjust the
TAZ system or the network to bring it in line with the validation year network or to adjust the validation year network so that it is comparable to the survey year network.
3.3 SCREENLINE AND CUTLINE CHECKS
Even though network development procedures were designed to produce a compatible TAZ system and highway network, additional checks for com- patibility should be made after the initial traffic assignments for the validation year have been made. For each screenline and cutline, the number of crossings indicated from ground counts should be compared to the number indicated by the validation year traffic assignment. If the assignment volumes are higher than the ground counts at screenlines, other roadway
(collectors) should be added or zones should be deleted. Similarly, if the counts are higher than the assignment, roadways should be deleted or zones should be added. Since it is difficult to change the zone structure, adjustments are usually made by adding or deleting roadways.
Screenline problems could also stem from inaccuracies in the trip generation or distribution models. Adjustment of these models is a part of model validation that is beyond the scope of this report.
62 4. NETWORK UPDATING
Chapter 2 described the development of a highway network from scratch.
This chapter explains the methodology for updating a network that was developed in accordance with the standard procedure described in Chapter
2. This updating procedure should be used when developing a future year alternative from a validation or existing network, or when developing a variation of a future year network. The procedure described herein assumes that the base network has been completely debugged and that all changes (updates) represent physical changes in the highway system, not corrections of errors.
All network criteria were described in Chapter 2; they are not repeated here. The following steps define a procedure to be interfaced with the information contained in Chapter 2 in an updating process.
4.1 OBTAIN HIGHWAY NETWORK MAPS
Most of the data appearing in the highway network link file are illustrated by the mylar highway network maps. The first step in the updating process will be to obtain blue-line prints and duplicate mylar or film copies of the network maps. The blue-lines will serve as work maps for developing the new alternative. Mylars should be made only if the alternative being developed is the existing system, the needs plan, the adopted plan, or an interim network. The mylars will serve as the permanent network maps for the new alternative and thus should be printed on a material that will allow the lettering and line work to be changed.
63 4.2 OBTAIN A LIST OF THE HIGHWAY NETWORK LINK FILE
Changes to be made in the network link file will be noted on a copy of
the link file before they are entered into the computer. A list of the
file, preferably double-spaced, on which to note the changes must be
obtained.
4.3 DRAW THE NETWORK CHANGES ON THE BLUE-LINE WORK MAP
Additions to the base network should be sketched on the blue-line maps
and links to be deleted should be marked through. The data items that
will be inked on the mylar later should be noted on the prints; direc-
tional arrows should be shown in the case of one-way streets; facility
type and number of lanes should be marked, and construction codes should
be indicated if they are being used in the study. Node numbers should be written on the prints; they should conform with the systematic numbering
scheme. If nodes are eliminated, their numbers should not be reused.
4.4 PREPARE THE MYLAR NETWORK MAPS
If the alternative is important enough to justify a mylar base map, the
changes indicated on the blue-line print should be carefully transfered to the mylar. The descriptions of alternatives that appear in the bottom margin should also be changed (see Chapter 5).
4.5 CODE THE NETWORK CHANGES
All network changes should be coded on a list of the highway network
link file. Most of the data will already be marked on the blue-line work maps. District numbers should be determined by comparing the blue-
line work map with the blue-line district map. After the network data
64 have been coded, the modifications should be entered into a duplicate of the highway network link file data set. The standard conventions for naming data sets should be followed in creating the duplicate file.
In addition to modifying the link file, coordinate card images for each new node must be added to the coordinate file. Unless there is a very large number of new nodes, the digitization should be done manually.
The new coordinate card images should be added to the coordinate file using TSO. Since node numbers are not reused and since nodes that appear in the coordinate file but not in the link file are not flagged as errors, a single coordinate file can be maintained for each urban area.
4.6 PLOT THE NETWORK
The network should be plotted to show 1 inks and nodes, node numbers, and centroid connectors, as explained in section 2.13. After errors in the network have been corrected, the network data should be plotted as ex- plained in section 2.2.1 With the correction of all errors and plotting of data, the network is ready for use in the travel demand models.
65 5. STANDARD DATA SET NAMES
The FDOT Urban Transportation Planning Procedure T-3 defines conven- tions for naming data sets. These conventions simplify the understand- ing of data set names by different users, and they must be applied if the Driver command procedures are to be used. This chapter describes the conventions in detail.
5.1 COMPONENTS OF DATA SET NAMES
Data set names can be constructed from the components presented in Ta- bles 5-l through 5-6. These components are called fields, and are com- posed of up to eight characters. A word can have as many as eight char- acters and can be made from one or more fields. A data set name com- prises one or more words separated by decimal points. A data set name describes the contents of the data set, and each data storage device has different requirements for the format of the name.
The most often used string of characters is "PL931," an identification for the Bureau of Urbanized Area Systems Planning. The other fields serve the following functions:
. Study area ID - These two-character fields identify the
urban area transportation study for which the data are
used (Table 5-l).
. Standard data descriptions - These fields provide a techni-
cal description of the kind of data in the data set (Table
5-2).
. Standard optional words - These words can be used to clarify
the contents of the data set (Tab?e 5-3).
66 TABLE 5-l
STANDARD TWO-CHARACTER STUDY AREA IDENTIFICATION
Abbreviation Urban Area Transportation Study
BA Bay County Transportation Study
BE Brevard Area Transportation Study
BO Broward Area Transportation Study
FP Ft. Pierce Transportation Study
FT FTOWN (test data set)
FT Ft. Walton Transportation Study
GA Gainesville Urban Area Transportation Study
JA Jacksonville Urban Area Transportation Study
LE Lee County Transportation Study
MI Miami Urban Area Transportation Study
NA Naples Transportation Study
OC Ocala Transportation Study PA Pasco Transportation Study
PB West Palm Beach Urban Area Transportation Study
PE Pensacola Urban Area Transportation Study
PI Pinellas Area Transportation Study
PO Polk County Transportation Study
SM Sarasota-Manatee Area Transportation Study
TB Tampa Bay Regional Transportation Study (com- bines Pinellas and Tampa studies plus Pasco County)
TL Tallahassee Urban Area Transportation Study
TM Tampa Urban Area Transportation Study
vo Volusia County Area Transportation Study
Source: Florida Department of Transportation.
67 TABLE 5-2
STANDARD NETWORK-RELATED DATA DESCRIPTIONS
Abbreviation Definition
AT Area Type
EVAL Evaluation
FT Facility Type
HASSIGN Highway Assignment HNET Highway Network HR Highway Historical Record HRLD Loaded Highway Historical Record HRLDXY Loaded Historical Record with Coordinates HRXY Highway Historical Record with Coordinates HWY Highway
LINKS Link Cards LN Lanes LS Level of Service
PLOT Plots
TAZ Traffic Analysis Zone
VCAP Volume and Capacity VCNT Volume and County
XY Coordinate
Y Year
Source: Florida Department of Transportation:-*
68 TABLE 5-3
STANDARD NETWORK-RELATED OPTIONAL WORDS
Abbreviation Definition
ALT Alternate AP Adopted
EDIT Edit EPA Existing Plus Assured EPC Existing Plus Committed EXTG Existing
INTM Interim
REV Revised RP Recommended Plan
UPD Update
Source: Florida Department of Transportation.
69 . Category fields - These one-digit fields describe the con-
tents of a magnetic tape data set, and are used to save space
because a tape data set can contain only seventeen characters
(Table 5-4).
. Data type words - Data type words (Table 5-5) describe the
data processing characteristics of the data.
. Year/alternative/version field - This field describes the
planned years and alternative designation of the network
(Table 5-6).
DATA is usually information read or written by another program. CNTL data sets contain job control language, are usually job set-ups, and are the data sets submitted using the TSO QSUB command. CLIST data sets are
TSO command procedures that are executed in the foreground. FORT data sets contain only FORTRAN statements and are called by the foreground
FORTRAN compiler or by a batch job FORTRAN compiler step. LOAD data sets are produced by a FORTRAN compiler and cannot be edited with the
TSO full-screen editor (QED).
5.2 ON-LINE DISK DATA SET NAMES
Frequently used data sets are usually stored on the on-line disk packs.
Data sets must be on-line if they are to be edited with QED.
On-line data set names take the general form shown in Table 5-7. Fields
1, 2, 3, and 9 must be included in the data set name. Field 2 identifies the study area. Fields 3 through 5 describe the data. Fields 6 and 7
70 TABLE 5-4
CATEGORY FIELD DEFINITIONS
Category Definition
Survey records Inactive land use/socioeconomic data Inactive link/coordinate data Trip tables Other zonal matrices (not used) (not used) (not used) Miscellaneous
Source: Florida Department of Transportation.
TABLE 5-5
DATA TYPE WORDS
Word Description
DATA General data (EBCDIC or machine code) CNTL A file containing Job Control Language CLIST A file containing TSO commands FORT A file containing only FORTRAN statements LOAD A file containing a FORTRAN load module in machine code
Source: Schimpeler.Corradino Associates.
TABLE 5-6
YEAR/ALTERNATIVE/VERSION WORDS
Field Description Columns
Year "Y" and the last two digits of 3 the year
Alternative A single letter (A-Z) 1
Version A single integer (l-9) 1
TOTAL 5
Source: Schimpeler*Corradino Associates.
71 TABLE 5-7
ONLINE DISK DATA SET NAMES
PLg31 Xx . TTAB l HWY . TRN . Y80 Al l $V_ e DATA 1 2 3 4 5 6 7 8 9
Source Field Description Table
1 PL931 (no options) None
2 Study area ID (mandatory) 5-l
3 Primary data description word (mandatory) 5-2
4 Secondary data description word 5-2
5 Tertiary data description word 5-2
6 Y (year) and last two digits of the year 5-6
7 Two-character alternative/version designation 5-6
8 Optional word 5-3
9 Data type word (mandatory) 5-5
Note: The entire data set name, including decimals, may con- tain a maximum of 41 characters. Data set names cannot contain imbedded blanks; the blanks in the example above show the division between fields and words.
Source: Florida Department of Transportation.
72 designate the year and alternative, respectively. Field 8 contains the
optional description word. Fields 4 and 8 are optional. An on-line disk
data set name cannot be more than 41 characters long.
5.3 OFF-LINE DISK DATA SET NAMES
Less frequently used data sets are stored on off-line disk packs. These
data sets must be moved on-line before they can be edited with QED or
used in a foreground procedure. An off-line disk data set can be
accessed only by a background job.
Off-line disk data set names are very similar to on-line names, with two exceptions (Table 5-8): off-line disk data set names can contain as many as 44 characters, and all off-line names contain "PL931OL" in field
1 (the study area identification appears as a second word in field 2).
73 TABLE 5-8
OFFLINE DISK DATA SET NAMES
PL93lOL . XX . TTAB . HwJ. TRN . YOO Al . REV_ . DATA 1 2 3 4 5 6 7 8 9
Source Field Description Table
1 PL931OL (no options) None
2 Study area ID (mandatory) 5-l
3 Primary data description word (mandatory) 5-2
4 Secondary data description word 5-2
5 Tertiary data description word 5-2
6 Y (year) and last two digits of the year 5-6
7 Two-character alternative/version designation 5-6
8 Optional word 5-3
9 Data type word (mandatory) 5-5
Note: The entire data set name, including decimals, may contain a maximum of 44 characters. Data set names cannot contain imbedded blanks; the blanks in the example above show the division between fields or words.
Source: Schimpeler.Corradino Associates.
74