Olympic Delivery Authority
M11 Logistics Centre Transport Assessment Report August 2008
planning Olympic Delivery Authority – Logistics Centre 1 Transport Assessment Report R12095T112
– OLYMPIC DELIVERY AUTHORITY LOGISTICS CENTRE 1 TRANSPORT ASSESSMENT
R12095T112 Issue Date Originator Checked Approved For Approval 14 August 2008 ACS CJO JAC
This report is to be regarded as confidential to our Client and it is intended for their use only and may not be assigned. Consequently and in accordance with current practice, any liability to any third party in respect of the whole or any part of its contents is hereby expressly excluded. Before the report or any part of it is reproduced or referred to in any document, circular or statement and before its contents or the contents of any part of it are disclosed orally to any third party, our written approval as to the form and context of such a publication or disclosure must be obtained
Prepared for : Prepared by :
Olympic Delivery Authority Pell Frischmann Consulting Engineers One Churchill Place 5 Manchester Square Canary Wharf London London W1A 1AU E14 5LN
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Olympic Delivery Authority – Logistics Centre 1 Transport Assessment Report R12095T112
CONTENTS
1 INTRODUCTION...... 3 1.1 Background to the Study and Project Objectives ...... 3 1.2 Scope and Objectives of the Report...... 3 2 THE PROPOSED LOGISTICS CENTRE...... 4 2.1 Function, Location and Access ...... 4 2.2 Proposed Layout...... 6 3 TRAFFIC FLOWS...... 9 3.1 Existing Situation ...... 9 3.2 Traffic forecast ...... 9 3.2.1 Horizon year...... 9 3.2.2 Background Traffic Growth...... 10 3.2.3 Trip generation created by the Logistics Centre...... 11 3.2.4 Traffic arrangements internal to the Logistics Centre...... 11 3.2.5 Traffic flows external to the Logistics Centre ...... 12 4 JUNCTION APPRAISAL...... 15 4.1 M11 on-slip roads capacity assessment...... 15 4.2 M11 on-slip roads: TD22/06 (paragraph 3.3) Capacity Assessment...... 18 4.3 Junction 5: M11/Chigwell Lane Assessment ...... 19 4.3.1 2007 Base year situation...... 20 4.3.2 2011 Scenarios ...... 22 4.3.3 Traffic operations at Chigwell Lane...... 23 4.3.4 Conclusion with respect to Chigwell Lane...... 23 4.4 Junction 4: M11/North Circular Road ...... 24 4.5 M11 Mainline Weaving between J5 and the Logistics Centre...... 26 5 GEOMETRIC DESIGN APPRAISAL...... 27 5.1 Slip Road Layouts...... 27 5.1.1 Road Signing...... 28 5.1.2 Road Safety ...... 29 6 CONCLUSION...... 30 APPENDIX 1: M11/CHIGWELL LANE SIGNALISATION...... 31 “ ” APPENDIX 2: 2012 DURING THE GAMES TRAFFIC IMPACTS...... 32 APPENDIX 3: 2011 FLOWS - EAST OF ENGLAND REGIONAL MODEL...... 36 APPENDIX 4: ACCIDENT ANALYSIS...... 38 M11 Accidents ...... 38 Chigwell Lane Accidents...... 41
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Olympic Delivery Authority – Logistics Centre 1 Transport Assessment Report R12095T112
1 INTRODUCTION 1.1 Background to the Study and Project Objectives The Olympic Delivery Authority (ODA) propose to construct and operate Logistics “ ” Centre 1 on a Highways Agency works unit site on the M11 between the junction with the A1168 and the A406 (junctions 5 and 4 respectively). The functions of the Logistics Centre 1 are (i) to assist in the management of construction/delivery vehicle flow and access to the main Olympic Site in Stratford, East London by enabling vehicles to be assembled and called to the construction site in the most efficient manner to assist the Olympic Site construction and (ii) to allow security checks of vehicles to be undertaken before they reach the Olympic Site construction site. 1.2 Scope and Objectives of the Report This Transport Assessment (TA) supports a Planning Application for the proposed Logistics Centre to the planning authority, Epping Forest District Council. The traffic and highway aspects will be considered by the relevant highways authorities, namely the Highways Agency (HA) for M11 impacts and Essex County Council for Chigwell Lane impacts. The TA has been prepared in accordance with the Brief issued by ODA (agreed with the HA before the commencement of the commission) and in “ – accordance with the Guidance on Transport Assessment Communities and Local ” – “ ” Government and Department of Transport (March 2007 version the Guidance ). The TA draws upon, and analyses, traffic data collected in and 2007, accident data for the last 3 years and topographic surveys. The objectives of the TA are to assess (i) the adequacy of the transport system to meet travel demand arising from the Logistics Centre and (ii) the impacts of the Logistics Centre on the surrounding transport and highway network.
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2 THE PROPOSED LOGISTICS CENTRE 2.1 Function, Location and Access To establish the context for the analysis of transport issues relating to the proposed development, the function and operation of Logistics Centre 1 is summarised as follows: As noted in Section 1, the Logistics Centre 1 functions are to manage the arrival of construction vehicles to the main Olympic Site and to enable security checks to be carried out on vehicles in accordance with sampling procedures established by the ODA; “ ” Vehicles will be given an arrival time which currently is proposed at 3 hours duration during which they must arrive at the site; if they are outside this “ ” arrival slot , they will be rejected and return immediately to the M11; “ ” Vehicles arriving from the M11 will pass through Reception Gate 1 (which will comprise 5 channels, similar to road toll booths) where they will be checked to ensure they are within their allocated arrival time, that vehicles ’ and drivers are as defined by the ODA s delivery management system (DMS) which applies to all construction vehicles entering the Olympic Site – construction site; additionally vehicles will be subject to an initial inspection estimated length of these processes is 1 minute duration; Vehicles will move on either to a parking area where they will wait to be called to the construction site or, a sample of vehicles will be selected to pass through Gate 2 for load inspection; Gate 2 will comprise a hard standing to enable load inspection and reconcile delivery documents; Vehicles passing the inspection at Gate 2 will pass to the parking-storage area (where they will rejoin the vehicles not subjected to Gate 2 inspections) where they will wait to be called to the Olympic Site construction site; vehicles failing the inspection will be sent back to the M11 under supervision or made the subject of full load breakdown inspections; The ODA seek to make the Logistics Centre 1 operational as soon as possible; the Centre will be used (i) for the construction of the Olympics site through programmed completion of construction in 2011, (ii) for delivery vehicles during the Games itself in 2012 and for de-construction and legacy transformation to the Olympic Site during 2013. Beyond December 2013, the Centre will not be used and will be returned to its present open land form. The ODA will initially operate the Centre at a low vehicle flow and will build to capacity (a maximum of 130 vehicles may be parked at the site) as operational familiarity is gained to allow increase to full capacity The proposed Logistics Centre 1 is located on the M11, approximately 6.5km south of Junction 6 of the M11 with the M25 and 2km south of Junction 5 at Chigwell Lane. The main entrance to the Olympic Site is located about 12km to the south and is reached by the M11, the A406 and the A12 as illustrated in Figure 2.1.
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Junction 6 M11/M25
M11
M25 Logistics Junction 5 Centre 1
Junction 4
A12 A406
Olympic Site
Figure 2.1 Location Map “ ” The total area of the Highways Agency works unit site is approximately 8ha. The site is divided, more or less centrally, by the M11 into two sub-areas. The eastern side sub-area is approx 3.5ha and the western side area approx 4.5ha. The general configuration is summarised as: Both sub-areas are served by slip roads on-off the M11. Each carriageway of the M11 adjacent to the site has three lanes. However, approximately 2km south of the site, the southbound M11 carriageway reduces to two lanes; “ ” Only the eastern sub area of the Highways Agency works unit site will be used as the Logistics Centre 1; Vehicle entry to the eastern sub-area of the Logistics Centre 1 Site (to be used by Logistics Centre 1 vehicles) from the north will be from the M11 southbound. Vehicle access to the Site from the M11 northbound will be via a “ ” U-turn at Junction 5 (Chigwell Lane). The distance between the Site and Junction 5 is approximately 2km. If vehicles cannot enter the Site (see above – “ ” if vehicles miss their 3 hour arrival slot ), the return routes are: “ ” Right to North Circular Road at Junction 4 (4.1km) and U-turn on A406/A104 roundabout (5.3km); or “ ” Left to North Circular Road at Junction 4 (4.1km) and U-turn on Eastern Ave roundabout (5.5km).
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Currently both east and west sub areas of the Site are predominantly vacant with the exception of an Essex Police Control Centre located on the northern boundary of the western sub-area; it has been agreed in discussions with the police, that police operations of their Centre will not be affected by Logistics Centre 1; “ ” The two sub-areas of the Highways Agency works unit site are connected via a road-bridge over the M11 to the north end of the site. The bridge is one lane wide and has a 28 tonne weight limit. The bridge link between the east and west sub-areas is dedicated to police and emergency service use as it “ ” allows a U-turn for emergency vehicles to be made across the motorway. It has been agreed between ODA and the Police that the bridge cannot be used by Logistics Centre 1 traffic as this would impede police operations and as the bridge is effectively one way, could be hazardous (commercial vehicles conflicting with emergency vehicles even if, for example, traffic signal control was included at each end of the bridge); The sub-areas are also connected by an existing underpass designed for – pedestrians only movements within the Site located approximately central to the site. The underpass was never fully commissioned (for example, there are no access paths), is not used, entrances are heavily overgrown with vegetation and often flooded; and Both sub-areas are bounded by existing perimeter roads approx 6.5 m width. 2.2 Proposed Layout Various configurations for the proposed Logistics Centre were considered and Table 2.1 summarises the design parameters and Figure 2.2 for the preferred layout which forms the subject of the Planning Application. Table 2.1: Design Parameters for Internal Layout of the Logistics Centre Design Aspect Parameter 2011 (when the Logistics Centre will cease to provide facilities for the Olympic Site construction site)
ODA has considered the use the Design Year Logistics Centre to provide facilities for goods vehicles during the Games; thus an assessment is also made of the 2012 traffic effects under this condition (Appendix 2) – Preliminary reception gates 5 channels for vehicles General Configuration (based on queue – simulation model analysis) Load inspection gates 2 channels for vehicles with potential to expand to 3 channels if required Total -130 spaces
Number parking spaces Conventional large trucks - 91 spaces
Large (16.5m) trucks - 39 spaces Vehicle entry and exit to all parking Principles of parking area design “ ” spaces, gate 1, gate 2, load inspection Page 6
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Design Aspect Parameter areas etc made by vehicles moving – forwards no reversing of vehicles on site – Parking Area hardstanding gradient Max 2.5% – Not relevant all circulation roads, parking areas, access to entry and exit junctions etc planned to deal with swept – Parking area design speed for vehicles paths for manoeuvring (forwards) of 18.5 articulated/drawbar vehicles (as well as 16.5m articulated and 12m rigid vehicles) – Parking Area circulation area gradient Max 5% – Parking Area security gate gradient Max 1.7% – Parking Area parking bays for 3.5m x 14m standard trucks – Parking Area parking bays for large 3.7m x 18.25m trucks Internal circulation aisles within parking 8m wide minimum area Access and internal circulation roads Inner radius 10m Maximum design vehicles for 2.5m x 16.5 m manoeuvring An Operational Management Plan will be in force. The sequence of operations is illustrated in Figure 2.2. The Plan will ensure Vehicles are directed to the allocated routes (via a series of automated barriers-gates which determine the route to be taken) Vehicles are directed to their Operational Management Plan allocated parking isles and bays “ ” Vehicles are called to proceed to the Olympic Site construction site as required Incident procedures are in place to deal with broken down vehicles (a tow truck will be permanently on site), to deal with accidents or to prevent any vehicle queue extending onto the approach slip and towards M11
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Figure 2.2: Proposed Design
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3 TRAFFIC FLOWS 3.1 Existing Situation Traffic surveys were undertaken by ARUP on behalf of the ODA in July 2007 on the M11 from Junction 6 - between the M11 and the M25 - to Junction 4 - between the M11 and the North Circular Road - including M11 on and off slip roads of the proposed site. The results of the survey are summarised in Figure 3.1 for the morning peak (08:00- 09:00) and the evening peak (17:00-1800).
355
440
129 Junction 5- Chigwell Lane 452
2704 3712
4639 3001
13 3
11 2
AM 08:00-09:00 PM 17:00-18:00
Junction 4
Figure 3.1: Base year Situation- Observed Flows (Veh/hr) on the 17 July 2007 3.2 Traffic forecast
3.2.1 Horizon year “ ” Development of traffic options to accommodate the design year traffic and to make “ ” reliable forecasts of future year traffic effects requires definition of a horizon year and realistic assumptions concerning the future traffic growth. The Centre will cease to function in its primary form (as a security/materials/goods delivery vehicles centre) in 2011 and this has therefore been taken as the horizon year for traffic forecasts; “ ” this represents the worst case of background traffic. In 2011, the traffic effect with the Logistics Centre 1 in operation will comprise two elements (i) background traffic (existing traffic projected to the 2011 horizon year) and (ii) Logistics Centre goods/materials vehicles at 2011. The derivation of the traffic flows is set out in this section The following discussion describes the future demand estimation for the future horizon of 2011.
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The potential use of the Site during the Olympics Games in August 2012 has been assessed and this is presented in Appendix 2.
3.2.2 Background Traffic Growth General background future traffic demand estimates were determined by applying TEMPRO1 growth factors for 2011 to the existing 2007 traffic flows. “ ” TEMPRO factors were derived for the Epping Forest District and are summarised in Table 3.1. Table 3.1: 2007 to 2011 TEMPRO factors 2007-2011 Time Period Factor AM Peak (7am-10am) 1.046 Inter Peak (10am-4pm) 1.050 PM Peak (4pm-7pm) 1.046 “ ” “ ” “ ” “ Figures for Great Britain , Outer London , Essex and London Borough of ” Redbridge were considered in comparison. All the factors were broadly similar (4%- “ ” 5% in 2011 and 5%-6% in 2012 at 2007 base). Epping Forest generally represented the worst case (i.e. maximum) growth scenario in all periods and “ ” therefore the Epping Forest factors were selected for both this reason and the locational relevance. The factors, which as shown in Table 3.1, differ with regard to time period, were applied to the relevant base flows. Figure 3.2 illustrates the background traffic flow in 2011.
371
460
135 Junction 5- Chigwell Lane 473
2828 3883
4852 3139
14 3
11 2
AM 08:00-09:00 Junction 4 PM 17:00-18:00
Figure 3.2: 2011 background traffic flow (Veh/hr)
1 TEMPRO - Trip End Model Projections of Growth in Travel Demand Page 10
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It is noted that road widening works are scheduled to take place on the M25. However, discussions with the Highways Agency have determined that these M25 works are not anticipated to affect traffic flows on the section of the M11 adjacent to the Site. It is noted that 2011 flows extracted from forecasts of the East of England Regional Model (EERM) were provided by the Highways Agency to the Study Team. As flows on the concerned links (M11 from Junction 5 to 4 inclusive) in 2011 are lower in the EERM forecasts than in the TEMPRO forecast (and than the current flows), this does not appear realistic and the following analyses are based on the conservative future background traffic calculated from the TEMPRO factors as illustrated in Figure 3.2. EERM forecast flows are reported in Appendix 3.
3.2.3 Trip generation created by the Logistics Centre Increased traffic flow will be generated to/from the Logistics Centre 1, by goods/delivery vehicles and the analysis has assessed the likely traffic demand that will be generated. The following assumptions were made for the trip generation calculations and the distribution of the traffic for the Logistics Centre 1. Traffic volume estimates balance a number of interrelated factors including (i) the capacity of the Logistics Centre to accommodate waiting materials/goods delivery vehicles, (ii) the time periods required for security checking and clearance of vehicles and the need to avoid traffic queues which might interfere with M11 traffic flows and (iii) the constraints at the Olympic Site to accept delivery vehicles etc.
3.2.4 Traffic arrangements internal to the Logistics Centre A Queue and Delay Simulation Model has been developed and has been used to test traffic impacts and the key inputs, constraints and outputs are set out in the following Tables 3.2-3.4. Modelling was concerned with the Logistics Centre operation only and takes no account of external flows and interaction. Table 3.2: Design Parameters-Inputs to the Queue and Delay Simulation Model Input Unit Design Parameter Vehicles per Controllable by Construction Management Vehicle entry flow hour 100 veh/hr maximum Controllable by Construction Management Time limit on site Hours 3h maximum Number of gates for vehicle Gates Determined by model reception Determined by process modelled Duration of vehicle reception Minutes Defined as 1 min Determined by process modelled Duration of load inspection Minutes Defined as 2 min Table 3.3: Constraints-Outputs of the Queue and Delay Simulation Model Output Unit Constraints Queue from 1st gate Vehicle Traffic queue-back cannot extend to M11 Queue from 2nd gate Vehicle Constrained by the layout/capacity of the site Parking (holding area) Vehicles Limited by the physical size of the site occupancy Minutes per Constrained by the logistic requirement for Delays implied vehicle construction
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Table 3.4: Planning parameters (tested by the Model and defined by the ODA) Maximum entry flow 100 Vehicles per hour Maximum time in the Logistics Centre 3 Hours Parking Capacity 130 HGV parking spaces Reception (5 channels/gates) 1 Minute Load Inspection (2 to 3 channels/gates) 2 Minutes “ ” “ ” The requirements of Reception/Load Inspection and Holding/Parking have been balanced with assessed vehicle arrival/parking demand to create an effective and functional centre. Recognition has been made of possible delays for vehicles to pass through gates (as a result of high vehicle flows or if an accident closes a gate) to ensure that parking is adequate and to prevent critical traffic queue backs and queue interaction between the two gates or onto the M11. The outputs of the Model have assessed the operation of the Centre and based on the planning parameters shown in Table 3.4. It has been determined that 5 channels/gates at Vehicle Reception Gate 1, 3 channels/gates at Load Inspection Gate 2 and 130 parking spaces provide the best combined balance of arrangements to ensure effective operation and avoid any queuing back toward the M11 where it could affect traffic flows.
3.2.5 Traffic flows external to the Logistics Centre The Transport Assessment analysis assesses the capacity and operational impacts of the changes in traffic flow on the adjacent M11 and the key junction with Chigwell Lane which will arise from the Centre operations. The Logistics Centre traffic flows are derived from the following and are summarised in Figure 3.3. Flows generated by the Logistics Centre are defined by the capacity of a maximum of 100 vehicles per hour (flows are controllable as a Delivery Management System will be operational). It is assumed that 80% of the traffic arriving at the centre does so by “ traveling southbound on the M11 and that 20% does so by traveling northbound U- ” turning via Junction 5. This assumption is based on the location of the Centre in relation to main access routes (M11 north and M25 east and west) and the provision of a further Centre which, although final location has yet to be determined will capture vehicles from the south. Furthermore, the Delivery Management System will be able to control which vehicles-suppliers (and thus their direction of travel) will use the Logistics Centre 1. The Logistics Centre traffic flows additions are shown in Figure 3.3. The conservative assumption has been made that the Logistics Centre traffic will be generated in both peak periods whereas, it is likely that (i) AM Logistics Centre flows could be earlier than the AM general traffic peak and (ii) the PM Logistics Centre flows could be before the PM general traffic peak.
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80
0 80
0
20
20 20 20 Junction 5- Chigwell Lane
20 100
20 100
100
100
20 100 Logistics Centre 20 100
AM 08:00-09:00 PM 17:00-18:00
Junction 4
Figure 3.3: Peak Logistics Centre generated traffic flow (Veh/hr) between 2009 and 2011
The traffic flows generated by the Logistics Centre were added to the base traffic flows increased by the TEMPRO factors (shown in Table 3.1) to 2011. The percentage increases (where the base flow for that year is equal to 100%) for each of the peak periods are summarised below in Table 3.5 and Figure 3.4:
Table 3.5: Percentage increases on traffic Logistics Centre Link AM PM M11 NB (S of Site) 0.7% 0.4% M11 NB (N of Site) 0.7% 0.4% M11 SB (N of Site) 2.6% 3.2% 2011 M11 SB (S of Site) 2.6% 3.2% Off M11 to Chigwell Lane 14.8% 4.2% Chigwell Lane to M11 5.4% 4.3%
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20 371 391 5%
20 460 480 4%
20 135 155 15%
20 473 493 4% Junction 5- Chigwell Lane
20 2828 2848 1% 100 3883 3983 3%
20 4852 4872 0% 100 3139 3239 3%
0 14 14 0% 100 3 103 3333%
0 11 11 0% 100 2 102 5000%
20 2828 2848 1% 100 3883 3983 3%
20 4852 4872 0% 100 3139 3239 3% AM 08:00-09:00
PM 17:00-18:00
Logistics Base Junction 4 Total Centre 2011
Figure 3.4: 2011 Traffic flow with Logistics Centre
The Logistics Centre traffic flows (for goods/materials vehicles) are generally a low proportion of M11 flows traffic flows (less than 5%) and likely to be within normal main line variations of flow on the motorway. Proportional flows are greater on Chigwell Lane junction (15% traffic flow increase in the AM peak on the off-slip road from the M11 to Chigwell Lane).
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4 JUNCTION APPRAISAL 4.1 M11 on-slip roads capacity assessment In order to reflect the effect of the merging of traffic into the M11 from one side of a multi-lane carriageway, the volume to capacity ratio was calculated for each individual lane at the merge (lanes are designated in Figure 4.1).
1 2 3
M11 From SB Logistics Centre M11 NB
3 2 1
Figure 4.1: On-slip roads to the M11 Lane capacity is defined as 2330 pcu per hour as calculated from speed-flow curves for rural motorways defined in the Department for Transport National Transport Model Fitting of Regional Growth and Elasticities (FORGE) which took data from the DfT National Transport Model and updated it with data from the 2001 National Transport Survey. As noted in Section 3, background traffic in 2011 has been derived by factoring 2007 flows using TEMPRO factors and Logistics Centre traffic have been added to the appropriate lanes/direction; vehicles being converted to pcu by the factors shown in Table 4.1. These are also taken from Department for Transport National Transport Model Fitting of Regional Growth and Elasticities (FORGE) as they differentiate between different categories of HGV and are therefore considered more appropriate than general COBA factors given the known HGV vehicle-type mix of the surveyed flows and Logistic Centre traffic. Table 4.1: PCU factors by type of vehicles Vehicle Type PCU Factor Car 1.0 Light Goods Vehicle 1.0 Rigid Goods Vehicle 1.9 Artic Goods Vehicles 2.9 A conservative assumption has been made that a maximum 30% of the HGVs using the Logistics Centre would be articulated 18.25m HGVs while the majority are 12m rigid HGVs. Volume to capacity ratios at each lane are shown in Table 4.2.
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Table 4.2: M11 Volume to Capacity Ratios per lane at merging points Lane 2007 2011 Peak Direction Lane Capacity Flow Flow V/C V/C (pcu/hr) (pcu/hr) (pcu/hr) 1 2330 1108 0.48 1203 0.52 NB 2 2330 1143 0.49 1196 0.51 3 2330 827 0.35 865 0.37 AM 1 2330 1307 0.56 1587 0.68 SB 2 2330 1340 0.58 1402 0.60 3 2330 1431 0.61 1497 0.64 1 2330 1370 0.59 1477 0.63 NB 2 2330 1664 0.71 1741 0.75 3 2330 1828 0.78 1912 0.82 PM 1 2330 956 0.41 1220 0.52 SB 2 2330 1248 0.54 1305 0.56 3 2330 1034 0.44 1082 0.46
As flows grow to 2011, the Volume:Capacity ratio on M11 links/lanes increases. With the additional flows from background growth added to those generated by the Logistics Centre the Volume:Capacity ratio increases but remains below the 0.85 threshold (at which point congestion is likely) in all cases Traffic diverging and merging at the Logistic Centre 1 slip roads are summarised in the figure 4.2 for the peak hour. Analysis of the slip road/main carriageway merging/ diverging effects has been made based on the Design Manual for Roads and Bridges (Volume 6 Section 2 TD 22/06 Figure 2/3 MW and Figure 2/5 MW, Department for Transport) and show that the additional traffic does not require mitigation measures (such as additional slip or main carriageway lanes) and that the impact of the Logistics Centre on the M11 and its adjacent slip roads is concluded as negligible.
1022 102 Logistics 780 103 Centre
M11 SB
AM (veh/h) PM (veh/h)
Figure 4.2: Merge and Diverge flows in 2011 (Inclusive of background flow)
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Figure 2/3 MW Motorway Merging Diagram
Figure 2/5 MW Motorway Diverging Diagram
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4.2 M11 on-slip roads: TD22/06 (paragraph 3.3) Capacity Assessment Although not wholly appropriate for the motorway surrounding Logistic Centre 1, due to the fact that the motorway already runs over the given threshold value, it is noted that TD22/06 gives a maximum flow value of 1800 vehicles per hour per lane for use in the design of grade-separated junctions. Therefore, for completeness, the following analysis summarises the results of such a consideration: Table 4.3: Lane Capacity Analysis using TD22/06 1800vph/lane threshold Lane 2007 2011 Pk Dir Lane Thresh. Flow % Flow % (vph) (vph) Thresh. (vph) Thresh. 1 1800 786 43.7% 842 46.8% NB 2 1800 1075 59.7% 1124 62.5% 3 1800 830 46.1% 868 48.2% AM 1 1800 977 54.3% 1122 62.3% SB 2 1800 1287 71.5% 1346 74.8% 3 1800 1446 80.3% 1513 84.0% 1 1800 1179 65.5% 1253 69.6% NB 2 1800 1614 89.7% 1687 93.7% 3 1800 1835 101.9% 1918 106.6% PM 1 1800 746 41.4% 880 48.9% SB 2 1800 1219 67.7% 1274 70.8% 3 1800 1033 57.4% 1080 60.0%
As the threshold represents the commencement of service degradation (i.e. the 85% – threshold of capacity) the NB Lane 3 value should be noted in the above table it is over 100%. It is clear that despite traffic contributions from the Logistic Centre to M11 the only lane to be over-threshold is the northbound Lane 3 (which carries no Logistic Centre traffic). This is the case currently and in the future growth years. Even on the southbound carriageway (where the Logistic Centre impact is greatest), the road remains below the threshold value at all times. The assessment shows that ’ whether PF s or the DMRB procedures are used, the impact on M11 is not to increase traffic to over-capacity flows.
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4.3 Junction 5: M11/Chigwell Lane Assessment As described in Section 3, there will be changes in traffic flow on the M11 at Junction 5 (Chigwell Lane) and therefore an assessment of junction capacity has been made. The capacity assessment of the northbound off slip road and southbound on slip road at the Chigwell Lane junction were undertaken using PICADY for the AM and PM Peak with traffic volumes as derived in Section 3; the assessment has been made for: Base Year Situation: 2007 base year observed traffic ; “ ” Scenario 1: Do nothing 2011 background traffic without the Logistics Centre; and Scenario 2: 2011 with Logistics Centre. The scenarios have been tested in PICADY, assuming two priority junctions, A and B as shown in Figure 4.3: (A) movement from the M11 off-slip right to Chigwell Lane; and (B) movement from Chigwell Lane to the M11 on-slip.
Figure 4.3: Junction 5 (Chigwell Lane) Schematic Layout “ ” “ ” Geometric inputs to the PICADY models for Junction A and Junction B are shown in Table 4.5 and Table 4.6 respectively.
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Table 4.5: Geometric inputs for priority junction A at Chigwell Lane Major Road Carriageway Width (m) 17m Major Road Kerbed Central Reserve Width (m) 4.5m Major Road Right Turning Lane Width (m) 2.2m Minor Road Width (m) 6.0m Minor Road Visibility To Right (m) 60m Minor Road Visibility To Left (m) 60m Table 4.6: Geometric inputs for priority junction B at Chigwell Lane Major Road Carriageway Width (m) 8.5 Major Road Kerbed Central Reserve Width (m) 0.0 Major Road Right Turning Lane Width (m) 5.0 Minor Road First lane Width (m) 4.2 Minor Road Second lane Width (m) 4.2 Minor Road Visibility To Right (m) 50.0 Minor Road Visibility To Left (m) 50.0 Major Road Right Turn Visibility (m) 90.0
It is noted that detailed topographic surveys have yet to be undertaken at Chigwell Lane; at this stage, the dimensions noted above are derived from satellite images and checked against 1:1250 Ordnance Survey plans. The dimensions are conservative.
4.3.1 2007 Base year situation Existing queue length surveys were undertaken at A and movement B and those results have been used for the calibration of the base year models (2007 existing situation). Queue lengths were collected every 5 minutes of the 12-hours period on Tuesday 17th July 2007. As illustrated in Figure 4.4 long queues occur for movement A (maximum 21 vehicles in the PM peak) and as illustrated in Figure 4.52, movement B has negligible queue (max 6 vehicles).
25
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h 15 e v
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e 10 b m u
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0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 4 2 0 4 2 0 4 2 0 4 2 0 4 2 0 4 2 : : : : : : : : : : : : : : : : : : 7 7 8 9 9 0 1 1 2 3 3 4 5 5 6 7 7 8 0 0 0 0 0 1 1 1 1 1 1 1 1 1 1 1 1 1 Time Figure 4.4: Queue length (veh) for movement A
2 Figures 4.4 and 4.5 are to different vertical scales; otherwise Figure 4.5 is not clear. Page 20
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7
6 s e
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0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 :0 :4 :2 :0 :4 :2 :0 :4 :2 :0 :4 :2 :0 :4 :2 :0 :4 :2 7 7 8 9 9 0 1 1 2 3 3 4 5 5 6 7 7 8 0 0 0 0 0 1 1 1 1 1 1 1 1 1 1 1 1 1 Time
Figure 4.5: Queue length (veh) for movement B
Traffic flows for the base year scenario 1 are summarized in Table 4.7 and 4.8. Table 4.7: Traffic Flow (veh/h) in 2007 for Chigwell Lane Junction A Link Destination Chigwell Lane Chigwell Peak Time Period Link Origin Slip road (North- Lane (South- from M11 westbound) eastbound) Chigwell Lane 0 0 897 (North-westbound) – AM 08:00 09:00 Slip road from M11 129 0 0 Chigwell Lane 1063 0 0 (South-eastbound) Chigwell Lane 0 0 436 (North-westbound) – PM 17:00 18:00 Slip road from M11 452 0 0 Chigwell Lane 1701 0 0 (South-eastbound)
Table 4.8: Traffic Flow (veh/h) in 2007 for Chigwell Lane Junction B Link Destination Minor- from Peak Time Period Link Origin Major slip road to Chigwell Lane M11 (South- eastbound) Major slip road to M11 – 280 0 AM 08:00 09:00 Minor- from Chigwell 355 0 Lane (South-eastbound) Major slip road to M11 119 0 – PM 17:00 18:00 Minor- from Chigwell 440 0 Lane (South-eastbound)
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The PICADY model outputs for Chigwell Lane Junction A in the base year situation are summarised in Table 4.9. In the PM peak the priority junction approaches a – degree of saturation of 100% with a queue of about 20 vehicles (as surveyed) this “ ” reflects the present situation and is a validation of the model for the junction. Table 4.9: PICADY Outputs for Chigwell Lane Junction A in 2007 Arm Demand/ Capacity Max. Queue Max. Arrival Delay Slip road from M11 (RFC) (Veh) (Min/Veh) AM 0.31 0.45 0.21 PM 0.997 20.12 2.71
The PICADY model outputs for Chigwell Lane Junction B in the base year situation are summarised in Table 4.10. Table 4.10: PICADY Outputs for Chigwell Lane Junction B in 2007 Arm Demand/ Capacity Max. Queue Max. Arrival Delay Minor- from Chigwell L (RFC) (Veh) (Min/Veh) AM 0.56 1.25 0.21 PM 0.635 1.72 0.24
4.3.2 2011 Scenarios Based on the outputs from the PICADY models, outlined in Table 4.11, it is clear that delays in junction A of Chigwell Lane, both in the base (2007) and future year (2011), are very high and in 2011 queues will cause considerable traffic congestion3. It is therefore considered that improvement to the junction will be required in all scenarios, as if not, the capacity would be greatly exceeded with traffic queues extending back to the M11. It is stressed that the congestion arises not from the – Logistics Centre 1 traffic generation but from the growth in background traffic adding to an already overloaded junction in the PM peak period. Table 4.11: PICADY outputs for Chigwell Lane junction A Junction A Demand Demand/ Capacity Max. Queue Max. Arrival Delay Slip road from M11 (veh/hr) (RFC) (Veh) (Min/Veh) Base year AM 129 0.31 0.45 0.21 2007 PM 453 0.997 20.12 2.71 Scenario 1 AM 135 0.368 0.58 0.26 2011 PM 473 1.108 54.03 6.32 Scenario 2 AM 155 0.422 0.72 0.28 LC 2011 PM 493 1.156 72.48 8.18 The PICADY models outputs for Junction B of Chigwell Lane are summarised in ’ Table 4.12. The junction is below capacity with RFC s of no more than 0.7.
3 – It is noted that the PICADY outputs are high approaching RFC of over 1 with queues of over 50 vehicles. It is of course the case that the junction would be unstable at such levels and that traffic would reassign routes, adjust times or be suppressed. The key point is that the levels indicate congestion and that the existing junction would not operate satisfactorily with full, unrestrained demand. Page 22
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Table 4.12: PICADY outputs for Chigwell Lane junction B Junction B Demand Demand/ Capacity Max. Queue Max. Arrival Delay Slip road from Chigwell L (veh/hr) (RFC) (Veh) (Min/Veh) Base year AM 355 0.557 1.25 0.21 2007 PM 440 0.635 1.72 0.24 Scenario 1 AM 371 0.613 1.57 0.26 2011 PM 460 0.692 2.21 0.29 Scenario 2 AM 391 0.647 1.81 0.28 LC only 2011 PM 480 0.722 2.55 0.32
4.3.3 Traffic operations at Chigwell Lane It is noted that Chigwell Lane is a dual 2 lane carriageway with a median approx 4.5m wide. Cars leaving the M11 northbound off-slip are able to cross Chigwell Lane in two manoeuvres as they are protected by the median (if they wait at an angle). HGVs must make the manoeuvre in one movement. Although HGVs make this manoeuvre today, an additional 20 HGVs per hour could make the manoeuvre when the Logistics Centre is operational. There have been two accidents involving right turns out of the slip road (although not involving HGVs) and improvements to the right turn from the slip road to Chigwell Lane could improve safety and is an additional reason to consider an improvement scheme.
4.3.4 Conclusion with respect to Chigwell Lane In 2011, the Chigwell Lane junction will be over capacity in the PM peak when the RFC will exceed 1; however, this is largely as a result of the growth in background traffic rather than the Logistics Centre 1 traffic. It is proposed that traffic delays and safety issues can be mitigated by converting the M11 northbound slip/Chigwell Lane junction to signal control. Appendix 1 sets out the implications of such a scheme and shows that the installation of new traffic signals on the northbound slip from M11 and Chigwell Lane can provide acceptable traffic operational conditions. The proposal would assist local traffic in the Chigwell Area as the majority of traffic using the M11 northbound slip road are likely to be local residents provide a Legacy of the Logistics Centre to local communities improve safe operations for HGVs leaving the slip road to turn right Appendix 1 sets out the initial capacity assessment and summarises the scheme design and processing implications.
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4.4 Junction 4: M11/North Circular Road
B C
D
A
Figure 4.6: M11/North Circular Road junction 4 Traffic flows to/from the M11 on/off slips to/from the North Circular Road A406 in the base year situation (2007) are summarised in Table 4.13. Table 4.13: Observed traffic flows (July 2007) at junction 4 AM Peak PM Peak Mvt From To Flow Capacity Flow Capacity V/C V/C (pcu/h) (pcu/h) (pcu/h) (pcu/h) M11 A406 A 2916 4660 0.63 2209 4660 0.47 Southbound Clockwise A406 M11 B 1844 4660 0.39 3127 4660 0.67 Anticlockwise Northbound A406 M11 C 1263 2330 0.54 1640 2330 0.70 Clockwise Northbound M11 A406 D 1554 2330 0.67 1167 2330 0.50 Southbound Anticlockwise
Table 4.14 shows traffic impacts in 2011 of the Logistics Centre where future background traffic is factored by TEMPRO factors at 2007 base, and the Logistics “ ” Centre traffic are combined to the appropriate lanes/direction with a split of U-turn flow of 50% across the two directions of the North Circular Road.
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Table 4.14: Traffic impact at junction 4 in 2011 Base Logistics Centre Total Capacity Peak Mvt Flow % inc. on Flow % inc. on Flow (pcu/h) V/C (pcu/hr) 2007 base (pcu/hr) 2011 base (pcu/hr) A 4660 3050 4.6 220 7.2 3270 0.70 B 4660 1929 4.6 22 1.1 1951 0.42 AM C 2330 1321 4.6 22 1.7 1343 0.58 D 2330 1626 4.6 0 0.0 1626 0.70 A 4660 2309 4.6 220 9.5 2529 0.54 B 4660 3269 4.6 22 0.7 3291 0.71 PM C 2330 1715 4.6 22 1.3 1737 0.75 D 2330 1220 4.6 0 0.0 1220 0.52
As flows grow into the future the volume to capacity ratio increases due to the slip road capacities. With the traffic flows from background growth and those introduced by the Centre, the volume to capacity ratios increased but they remain for all movements below the 0.85 threshold for the onset of congestion.
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4.5 M11 Mainline Weaving between J5 and the Logistics Centre
– As defined in paragraph 4.35 of TD22/06 (Design Manual for Roads and Bridges (DMRB), Department for Transport (DfT))), the desirable minimum weaving length between motorway junctions is 2km. The weaving length between M11 J5 and the off-slip into the Logistic Centre is 0.75km and must be assessed to ensure that (i) a departure from standard is not warranted; and (ii) the weaving flow generated by the Logistics Centre would not interfere with mainline flow and vice versa.
In response to these two points it is first noted that: No absolute minimum weaving length is specified for rural motorways in DMRB TD22/06; Both junctions are existing so there is no scope for extending the weaving length; HGVs are likely to be primarily in the nearside lane so HGV weaving movements are minimised (there are no HGVs in the offside lane by law); HGV diverge flows at the LC are low (max 100vph) and peak HGV exit flows will not coincide with peak J5 entry flows; and Total weaving flows are low (approximately 11% of mainline flow).
Paragraph 2.71 (TD22/06) specifies that the following calculation should be made – (where N is the number of lanes over the weaving section other parameters are defined in TD22/06 paragraph 2.71)4: N = (1/D) x (Qnw + Qw1 + Qw2(2(Lmin/Lact) + 1)) N = (1/1800) x (3712 + 355 + (100 x ((2 x (2/2)) +1))) N = 0.000555 x (3712 + 355 + (100 x 3) N = 0.000555 x (3712 + 355 + 300) N = 0.000555 x 4367 N = 2.426 lanes required It is noted that Paragraph 2.72 section ii, TD22/06, specifies that due to design flow uncertainty, a near 0.5 fraction should always be rounded up and thus the calculation leads to a conclusion that there is a requirement for weaving width (for desirable minimum length) of 3 lanes; i.e. equal to the current provision.
As no absolute minimum is specified for rural motorways, a comparison is made for an urban road with similar traffic flows and speeds; this requires an absolute minimum weaving length (extrapolated from Figure 4/14, TD22/06) of a little over 400m. The provision on the M11 is therefore, at 750m, almost double this requirement although this standard is for an urban 120km/h road and not a rural 120km/h motorway.
In conclusion, given the proposed signage and levels of traffic/weaving flows, the design is not considered to be a departure from standard and is considered to produce a negligible effect on the mainline M11 flow given the management of the centre (i.e. no queues will be permitted to back up onto M11) and for the other reasons detailed above.
4 Paragraph 2.67 TD22/06 requires that an actual weaving length below the desirable minimum not be entered into the formula reproduced above hence the inputs used in the above calculation Page 26
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5 GEOMETRIC DESIGN APPRAISAL 5.1 Slip Road Layouts Vehicles to-from the Logistics Centre 1 will use the existing slip roads on/off the M11. It is key to the design and safe operation of the Centre that the slip roads are of acceptable geometric standards. The required standards for merge and diverge junctions are defined in the DMRB (Volume 6 Section 2 TD 22/06, DfT) and the geometric standards to which the M11 Logistics Centre access slip roads should comply, are summarised in Table 5.1. The physical geometry for the existing and proposed on and off slip roads at the Logistics Centre 1 is shown on Figure 5.1.
Figure 5.1: Existing on-slip and off-slip roads to-from M11
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Table 5.1: Existing and proposed slip roads in relation to DMRB Geometric Standards Southbound off-slip from M11 DMRB geometric standards Existing Proposed Exit Taper Length >185m 180m 185m Off Nose Length >80m 59m 80 slip Taper Radius Approx1000 Approx 3000 roads Exit Loop Radius >75m 44m Infinite Southbound on-slip to M11 DMRB geometric standards Existing Proposed Entry Taper On >205m 343m Length slip Nose Length >115m 136m roads Entry Loop radius >75m 27m 75m
The geometric design is close to required standards and may be considered to be acceptable but the final design layout has proposed changes to the off-slip; these are (details are shown on the final design drawings): The nose length to be extended to 80m; this can be done by extending the nose northwards by the required amount and re-marking the nose; The start of the taper off the M11 would also be extended, again by re- marking the start point to give a length of 185m; The alignment of the slip road into the approach area of the Security Gate 1 would be straight and the layout in accordance with TA98/08 (DMRB 6.3.6, DfT) for Toll Gate approaches; Visibility equal to the mainline speed stopping sight distance (SSD; 295m) is required from the front of Gate 1. The slip road is aligned in a manner which provides this from the mainline in accordance with paragraph 4.18 in TD22/06 (DMRB 6.2.1, DfT).
“ The radius where the exit for vehicles joins the on-slip to M11 (termed the loop ” radius ) is less than the standard (27m against 75m). It is not possible to increase the radius due to physical constraints and equipment (a motorway communications control cabinet). The radius is of course used by emergency vehicles today and as the entry slip road is well in excess of standards (343m against 205m) it is considered that the reduced radius should have no operational effect on traffic leaving the Centre and joining the M11 southbound. It is also noted that the on-slip has a downward gradient and this should further assist acceleration to general traffic speeds on the nearside M11 lane.
5.1.1 Road Signing Road signing for the centre has been determined in accordance with the requirements set out in the DMRB and the Traffic Signs Manual.
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5.1.2 Road Safety Accident data have been collected for the last 3 years for the relevant sections of M11 and Chigwell Lane and accident/crash analyses carried out. Details of the analysis are included in Appendix 4. It is generally concluded that there are no significant adverse accident rates in the area although there have been 3 accidents in the vicinity of the M11-Chigwell Lane junction. A Stage 1 Road Safety Audit for the Logistics Centre has been carried out and the auditors report is awaited. The Audit was carried out by auditors independent of the Planning and Design team in accordance with the guidelines of the DMRB Volume 5 Section 2 (HD19/03). The Audit was not carried out previously since there have been changes in layout which have been necessary to (i) accommodate the constraints identified during final design and (ii) to meet comments made by various stakeholders. In line with conventional practice, a Stage 2 Safety Audit will be carried out on the basis of the detailed design.
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6 CONCLUSION The Transport Assessment Report demonstrates that the Logistics Centre, operated for goods/delivery vehicles, has minor traffic effects on the surrounding highway network. Detailed points are: The anticipated traffic flows (background traffic increased to 2011 plus Logistics Centre traffic) do not result in overloading of the nearside lanes of the M11 In 2011, traffic congestion is likely to exist at Junction 5 M11/Chigwell Lane in the PM peak when the RFC will exceed 1 but this is largely as a result of the growth in background traffic rather than the Logistics Centre 1 traffic. Technically, therefore responsibility for alleviating congestion should rest with the highway authority (Essex County/Epping Forest District Councils) but a solution to mitigate these traffic impacts – has been proposed namely the signal control of the northbound slip road and Chigwell Lane. Not only would this improve operations (by preventing a queue build back onto the M11) but would facilitate heavy goods vehicles leaving the slip road and thus improve safety. Implementation of new traffic signals will require very limited physical work and can provide acceptable traffic operational conditions and could be regarded as a Legacy Effect. The proposal has been discussed with Essex CC (highway authority for Chigwell Lane) and discussions are proceeding to determine (i) acceptability of the proposals and (ii) procedures for implementation. The following traffic, geometric and operational aspects of the Logistics Centre are noted: Traffic flows to-from the Centre will be controlled by the ODA through its DMS and Operations and Management Plan; the Plan will include incident management procedures to deal with vehicle breakdowns, accidents, traffic queue build back in the event of incidents etc The geometric standards of the access arrangements for the Centre to-from M11 have been discussed with the Highways Agency (the highway authority for M11) and are considered acceptable for the functioning of the Centre.
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APPENDIX 1: M11/CHIGWELL LANE SIGNALISATION As described in Section 4.2 of the TA, M11/Chigwell Lane junction is over capacity in all scenarios in the PM peak for movement A (the northbound slip from M11) and thus improvements are desirable. A preliminary layout has been prepared and has been submitted to Essex CC for comment. A Stage 1 Safety Audit Brief has been prepared and submitted to Essex CC for comment. The Safety Audit made no recommendations for change. The traffic signals control option has been investigated (by LINSIG junction modelling) and results are summarised in Table A1.1. Currently, the entry at the junction from the M11 slip road is 6.5m wide; LINSIG analysis is limited to a 5m per lane entry width (2 lanes is considered to pose a hazard without widening of the island gap) and thus analysis was performed with this value. In reality to avoid potential interpretation by drivers as a two lane approach, the carriageway would be hatched to reduce the width to a more acceptable dimension (here assumed 3.7m). Further LINSIG analyses were completed with this entry width and are highlighted in green in the following tables. The proposed stage sequence for the 4 options is shown in Figure A1.1:
Chigwell Lane Chigwell Lane
Off-Slip from M11 Off-Slip from M11
Figure A1.1: Stage Sequence Table A1.1: Junction modelling outputs in the PM peak for Scenario 1 and 2 – 5.0m entry width in white and 3.7m entry width in green
Cycle M11 off-slip Chigwell L Chigwell L Traffic Signal Entry flow South-eastbound North-westbound PRC Time Option off-slip (pcu/h) Delay Queue Delay Queue Delay Queue (s) (s/pcu) (pcu) (s/pcu) (pcu) (s/pcu) (pcu) Scenario 1: 478 11.4% 38 25.8 5.4 11.1 10.2 5.5 2.4 2011 Scenario 1: 478 11.9% 44 23.6 5.3 12.5 11.7 6.3 2.8 2011 Scenario 2: 518 11.9% 42 25.6 5.9 12.0 11.2 6.1 2.7 2011 with LC Scenario 2: 518 11.5% 48 25.0 6.0 13.4 12.6 6.9 3.1 2011 with LC
As illustrated in Table A1.1, for scenario 1 and 2 (2011 with/without the Logistics Centre) mitigation measures of traffic signals control of the junction with no physical widening are sufficient. Practical reserve capacity (PRC) exceeds 10% and queues are reasonable on the 3 arms of the junction (maximum queue length of 11 pcu). Discussions are proceeding with Essex CC and the HA to determine the authorities position and to identify the optimum procedures for progressing the scheme.
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“ ” APPENDIX 2: 2012 DURING THE GAMES TRAFFIC IMPACTS Subsequent to the completion of the TA for the operation of the Logistics Centre 1 in 2011, it was proposed that the Centre could be used in 2012 to control the supply of goods vehicles to the Olympic Site during the Games. Appendix 2 summarises the traffic effects of the Logistics Centre in 2012 and follows the same methodology described in the TA for the 2011 case. During the Games period, the ODA have taken the conservative view that planning “ ” for the during the Games scenario should assume traffic flow (for operational and service vehicles) using the facilities of the M11 Logistics Centre as equal to the peak period of construction (max 100 vehicles per hour). It is stressed that as for the period during construction, the demand will be managed through an Operational Management Plan and the DMS; thus the traffic volume can be controlled/limited. Similar to the construction period up to 2011, the Logistics Centre, operated for goods/delivery vehicles for the Games, has little traffic effects in 2012 on the surrounding highway network with the possible exception of effects on Chigwell Lane during the PM peak. The same analysis procedures have been used for the 2012 condition as the 2011 condition set out in the main text and are summarised in the following tables and figures. TableA2. 1: 2007-2012 TEMPRO growth factors Time Period 2007-2012 Factor AM Peak (7am-10am) 1.057 Inter Peak (10am-4pm) 1.061 PM Peak (4pm-7pm) 1.057
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375
465
136 Junction 5- Chigwell Lane 478
2858 3924
4903 3172
14 3
12 2
AM 08:00-09:00 PM 17:00-18:00
Junction 4
Figure A2.1: Background traffic flow (Veh/hr) 2012
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20 375 395 5%
20 465 485 4%
20 136 156 15%
20 478 498 4% Junction 5- Chigwell Lane
20 2858 2878 1% 100 3924 4024 2%
20 4903 4923 0% 100 3172 3272 3%
0 14 14 0% 100 3 103 3333%
0 12 12 0% 100 2 102 5000%
20 2858 2878 1% 100 3924 4024 2%
20 4903 4923 0% 100 3139 3239 2%
AM 08:00-09:00 PM 17:00-18:00
Junction 4 Logistics Base Total Centre 2012
Figure A2.2: 2012 Traffic flows with Logistics Centre
Table A2.2: M11 Volume to Capacity Ratios per lane at merging points in 2012 Lane 2007 2012 Peak Direction Lane Capacity Flow Flow V/C V/C (pcu/hr) (pcu/hr) (pcu/hr) 1 2330 1108 0.48 1215 0.52 NB 2 2330 1143 0.49 1208 0.52 3 2330 827 0.35 874 0.38 AM 1 2330 1307 0.56 1601 0.69 SB 2 2330 1340 0.58 1416 0.61 3 2330 1431 0.61 1513 0.65 1 2330 1370 0.59 1492 0.64 NB 2 2330 1664 0.71 1759 0.75 3 2330 1828 0.78 1932 0.83 PM 1 2330 956 0.41 1230 0.53 SB 2 2330 1248 0.54 1319 0.57 3 2330 1034 0.44 1093 0.47
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Table A2.3: Traffic impact at junction 4 in 2012 Base Logistics Centre Total Capacity Peak Mvt Flow % inc. on Flow % inc. on Flow (pcu/h) V/C (pcu/hr) 2007 base (pcu/hr) 2011 base (pcu/hr) A 4660 3082 5.7 220 7.1 3302 0.71 B 4660 1949 5.7 22 1.1 1971 0.42 AM C 2330 1335 5.7 22 1.6 1357 0.58 D 2330 1643 5.7 0 0.0 1643 0.71 A 4660 2333 5.7 220 9.4 2553 0.55 B 4660 3303 5.7 22 0.7 3325 0.71 PM C 2330 1733 5.7 22 1.3 1755 0.75 D 2330 1233 5.7 0 0.0 1233 0.53
As described in Section 4 of the Report, Chigwell Lane junction is currently over capacity in the PM peak. Therefore, unless traffic signal control is introduced at the junction, the situation will worsen in 2012. In the same manner as Appendix 1, an assessment of the proposed signal junction at Chigwell Lane in 2012 shows that the junction operation is satisfactory. Table A2.4: Chigwell Lane Junction modelling outputs in the PM peak – 5.0m entry width in white and 3.7m entry width in green (see Appendix 1)
Cycle off-slip Chigwell L Chigwell L Traffic Signal Entry flow South-eastbound North-westbound PRC Time Option off-slip (pcu/h) Delay Queue Delay Queue Delay Queue (s) (s/pcu) (pcu) (s/pcu) (pcu) (s/pcu) (pcu) Scenario 3: 483 11.0% 42 22.5 5.1 12.3 11.4 6.1 2.7 2012 Scenario 3: 483 11.9% 46 27.8 6.0 11.7 11.4 6.1 2.9 2012 Scenario 4: 523 10.9% 42 26.2 6.1 12.3 11.4 6.1 2.7 2012 with LC Scenario 4: 523 10.1% 50 24.6 6.1 14.2 13.4 7.2 3.3 2012 with LC
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APPENDIX 3: 2011 FLOWS - EAST OF ENGLAND REGIONAL MODEL As noted in Section 3 of the TA, 2011 flows extracted from forecasts of the East of England Regional Model (EERM) were provided by the Highways Agency to the Study Team. As illustrated below in Figure 1 and Table 1 traffic flows on the concerned links (M11 – from junction 5 included - to junction 4) in 2011 are considerably lower in the EERM forecasts than in the TEMPRO forecast. It is noted, as illustrated in Table 2, that EERM predicts that traffic volumes will reduce significantly from 2007 (as observed flows July 2007) to 2011. Without a detailed EERM audit (outside the scope of the TA), there is no known realistic basis for this reduction and as such a decrease is counter-intuitive, it has been concluded that the outputs of the EERM are not suitable for the Logistics Centre TA. It is considered that the TEMPRO based growth assumptions, used in the TA provide a more realistic, and moreover conservative, base against which to assess the impact of the LGC1 traffic impacts.
CL IN
Junction 5- Chigwell Lane
CL OFF
M11 NB N M11 SB N
Figure A3.1: Link diagram to inform Tables 1 and 2
Table A3.1: Comparison of EERM forecast flows to TEMPRO forecast flows in 2011 AM flow (veh) PM flow (veh) Link TEMPRO EERM Diff (%) TEMPRO EERM Diff (%) M11 Southbound M11 SB 3883 3404 -12% 3139 2898 -8% M11 Northbound M11 NB 2828 2695 -5% 4852 3834 -21% Off Slip to CL EB CL OFF 135 83 -39% 473 287 -39% From CL EB to on slip CL IN 371 237 -36% 460 339 -26%
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Table A3.2: Comparison of EERM forecast flows in 2011 to Observed flows in 2007 AM flow (veh) PM flow (veh) Link Obs 07 EERM Diff (%) Obs 07 EERM Diff (%) M11 Southbound M11 SB 3712 3404 -8% 3001 2898 -3% M11 Northbound M11 NB 2704 2695 0% 4639 3834 -17% Off Slip to CL EB CL OFF 129 83 -36% 452 287 -37% From CL EB to on slip CL IN 355 237 -33% 440 339 -23%
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APPENDIX 4: ACCIDENT ANALYSIS
M11 Accidents STATS19 data were collated for the 3-year period May 2004 to April 2007 (inclusive) for the M11 in proximity to the site, between Junctions 4 (North Circular) and 5 – (Chigwell Lane) inclusive a distance of approximately 6.2km. Accident rates were calculated and vary as shown in Figure A4.1 (unfilled points are ’ extrapolations for 2004 and 2007 (based on the known month s rates factored up to the year). Figure A4.1 includes a comparative plot of the predicted COBA combined “ ” link/junction accident rates for a D3 Motorway for the range of years considered. Accident rates generally appear lower than the predicted rates in COBA with a rate higher than the COBA prediction only in 2004 (although without previous data it is unknown if this is an unusual year or if there was a significant fall in accident rate between 2004 and 2005).
Accident Rate of M11 J5-4
0.120
0.100 ) m k v 0.080 m / a i p (
Accident Rate e
t 0.060
a COBA Rate R
t n
e 0.040 d i c c A 0.020
0.000 2004 2005 2006 2007 Year
Figure A4.1: Accident Rate for M11 J4-5 between 2004 and 2007 Generally, as would be expected for a grade-separated motorway, the majority of the accidents are distributed along the link with minimal clustering at junctions. The serious and fatal accidents are plotted below in Figure A4.2 and summarised in Table A4.1:
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– Table A4.1: Severity Split for M11 Accidents between J4-5 (May 2004 Apr 2007) Severity Number of Accidents % Fatal 1 3 Serious 6 15 Slight 32 82 Total 39 100
6 of the 39 recorded accidents (15%) were serious in nature and there was 1 recorded fatality (3%) in the time period concerned. This fatality involved a collision with the central reservation although was located 1.7km south of, and thus not influenced by, the Site.
5
Logistics Centre Site
M11
4
Figure A4.2: KSI Accident Plot (May 2004 - April 2007; red: fatal, orange: serious) Of the slight severity accidents that occurred in relatively close proximity to the Site, “ the causes were due to the usual expected mix of injudicious manoeuvres and rear
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” shunt accidents in congested conditions. None of the accidents involved any vehicles that were entering/leaving the carriageway from the proposed Logistics Centre Site. A plot showing the locations of the considered accidents in relatively close proximity to junction 5 (Chigwell Lane) is shown in Figure A4.3 and their distribution is summarised in Table A4.2:
M11
5
Figure A4.3: Accident Plot of M11 J5 (May 2004- April 2007; orange: serious, yellow: slight) Table A4.2: Location Split of Accidents surrounding M11 J5 Location Number of Accidents % Northbound 2 18.2 Southbound 5 45.5 Off Motorway 4 36.3 Total 11 100.0
Of the indicated accidents in Figure A4.3, 2 (18%) occurred on the northbound carriageway (the northernmost accident which appears on the northbound carriageway has been recorded erroneously and was in fact southbound), 5 (46%) on the southern carriageway and 4 (36%) were off the motorway on the intersecting road (Chigwell Lane). Page 40
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1 of the northbound accidents may have been related to the junction arising from an injudicious lane change towards the nearside although there is no evidence as to whether or not this vehicle was attempting to exit the M11 to use J5. The other (serious accident) is linked to the junction and was related to a similar injudicious lane change (this is an assumed link by the Police Officer as the driver responsible failed to stop). 2 of the southbound accidents were on or related to the slip road and both appear to involve braking errors and merging conflicts. This is likely a result of the entry loop which is of 80m radius (the minimum standard is 75m), the consequent low speed which vehicles entering on the slip road can achieve and the high speed differential which results between the merging and mainline traffic flows. The remainder of southbound accidents are not directly related to the slip road merge however 2 of them are related to poor/injudicious lane changing manoeuvres which may be more common here as a result of the merging traffic from the junction (although this would be expected).
Chigwell Lane Accidents
Accident Rate for Chigwell Lane
1.000
0.900
0.800 ) m
k 0.700 v m /
a 0.600 i p (
Accident Rate e
t 0.500
a COBA Rate R
t 0.400 n e d i 0.300 c c
A 0.200
0.100
0.000 2005 2006 2007 2008 Year
Figure A4.4: Accident Rate for Chigwell Lane between 2005 and 2008 (Hollow points are extrapolated for the full year based on available half-year data) Analysis of accident rates (Figure A4.4) on the relevant section (Figure A4.5) show this to be a relatively safe road in comparison with projected rates assumed in the COBA model. An upward trend is apparent but it should be noted that due to the comparatively low flows on Chigwell Lane the effect of individual accidents on the overall rates for each year is more significant than for a road with higher traffic flow. Details of the accidents considered are shown below in Table A4.3.
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– – Figure A4.5: Location plot of Chigwell Lane accidents June 2005 May 2008 (Key as Figure A4.3) Figure A4.5 shows that accidents tend to be involved with the M11 northbound off- slip or the signal junction with Langston Road and Oakwood Hill. None of the accidents involved pedestrians.
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Olympic Delivery Authority – Logistics Centre 1 Transport Assessment Report R12095T112
– Table A4.3: Stick Plot of Chigwell Lane Accidents (June 2005 May 2008) Reference I23600607 I26540707 I44591007 I10160108 I17700508 Day Monday Monday Wednesday Tuesday Monday Date 18/06/2007 02/07/2007 31/10/2007 15/01/2008 19/05/2008 Time 23:30 11:35 08:51 08:45 10:00 Visibility Dark (Lit) Light Light Light Light Surface Dry Wet/Damp Dry Wet/Damp Dry Severity Serious Slight Slight Slight Slight Casualties 3 2 1 1 1 Pedestrians 0 0 0 0 0 Vehicles 2 2 2 2 2 Conflict
Weather Fine-no Fine-no Fine-no Rain-no Fine-no wind wind wind wind wind Contributory Veh1: 602 Veh1: 406 Veh1: 405 Veh1: 602 Veh1: 108 Factors Veh1: 605 Veh1: 408 Veh1: 406 Veh1: 403 Veh2: 108 Veh2: 402 Veh1: 410 Veh2: 103 Veh1: 605 Veh2: 408 Veh1: 401 Table A4.3 shows that the majority of the accidents recorded involved a manoeuvring “ conflict (generally a poor turn; in one case a poor merge) with one involving a rear- ” shunt at a traffic signal queue. None of the accidents appear to be speed related and there does not appear to be an overrepresentation of accidents in certain conditions (e.g. in the wet or at night).
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