Minnesota Department of Transportation (MnDOT) Local Historic Bridge Report
Executive Summary Bridge Number: Milwaukee Road Railroad Bridge
The Milwaukee Road Railroad Bridge, built c.1930, historically carried the Chicago, Milwaukee, St. Paul & Pacific Railroad (Milwaukee Road) on a northwest to southeast alignment over Minnehaha Creek in Minnehaha Park, Minneapolis, Hennepin County, Minnesota. The bridge is owned by the Minneapolis Park and Recreation Board (MPRB). It is located along the now partially active railroad segment that runs northwest to southeast through southeast Minneapolis, starting south of East 27th Street, in the northwest corner of Minnehaha Park, south of Godfrey Parkway. The bridge is significant as a contributing component to the determined-eligible Grand Rounds Historic District.
The Milwaukee Road Railroad Bridge is a single span, reinforced-concrete, arch bridge with a span of 30 feet. The reinforced-concrete arch is 18 feet 8 inches wide and carries a single track of abandoned railroad with an interior width of 14 feet between headwalls. The abutments and wingwalls are all cast-in- place concrete.
The Milwaukee Road Railroad Bridge is in poor condition and is currently closed to all railroad and pedestrian traffic. The most significant defects of the bridge structure include spalling, cracking and delamination of the concrete arch, headwalls, wingwalls, and substructures; as well as heavy tree and vegetation growth on the surface of the fill between the headwalls and wingwalls. With proper maintenance, stabilization and preservation activities, it is believed the Milwaukee Road Railroad Bridge could be maintained in its current location for 20 years or longer.
Any work on this bridge should proceed according to the Secretary of the Interior’s Standards for the Treatment of Historic Properties (Standards) [36 CFR part 67] and The Secretary’s Standards with Regard to Repair, Rehabilitation, and Replacement Situations, as adapted by the Virginia Transportation Research Council (Guidelines).
JUNE 2017 Minnesota Department of Transportation (MnDOT) Local Historic Bridge Report
Bridge Location Bridge Number: Milwaukee Road Railroad Bridge
MILWAUKEE ROAD RAILROAD BRIDGE
MILWAUKEE ROAD RAILROAD BRIDGE OVER MINNEHAHA CREEK Bridge 448 – CSAH 18 over MID FK ZUMBRO RIVER
PROJECT LOCATION HENNEPIN COUNTY
SEC. 18 (SW 1/4 of NE 1/4), TO 028NN, R 23W
USGS QUAD NAME: ST PAUL WEST UTM ZONE: 15 NAD: 83
EASTING: 483179 m (1585228 ft.) NORTHING: 4973537 m (16317348 ft.)
JUNE 2017 Bridge Location Minnesota Department of Transportation (MnDOT) Local Historic Bridge Report
Bridge Number: Milwaukee Road Railroad Bridge Table of Contents
Executive Summary Bridge Location
I. Project Introduction II. Historic Data III. Bridge Data IV. Existing Conditions/Recommendations V. Projected Costs
Appendices
A. Glossary B. Guidelines for Bridge Maintenance and Rehabilitation based on the Secretary of the Interior’s Standards C. Documents
JUNE 2017 Table of Contents - i Minnesota Department of Transportation (MnDOT) Local Historic Bridge Report
I – Project Introduction Bridge Number: Milwaukee Road Railroad Bridge
This Bridge Report is a product of a comprehensive study performed for historic bridges owned by county, city, township, private and other state agencies besides MnDOT. The study is the third phase of a multi-phased process developed and executed in partnership with representatives from the Federal Highway Administration (FHWA); State Historic Preservation Office (SHPO); MnDOT State Aid; MnDOT Cultural Resources Unit (CRU); the US Army Corps of Engineers (USACE); local public works and county highway departments; county and township boards and city councils; the preservation community and the general public. To perform the study, MnDOT retained the consultant team of LHB Inc., Mead & Hunt Inc., and The 106 Group Ltd.
The general goals of the study include: • Identification of bridges not included in the SIMS database or identified in previous studies, to either be studied further (those on local roads/systems) or tabulated for SHPO’s use (trails and abandoned bridges)
• Gathering existing historic data, bridge condition data, and other relevant information on the bridges in the study group and compiling into bridge reports
• Re-evaluation of Chicago, Milwaukee & St. Paul Grade Separation Historic District (Midtown Corridor)
• Preparing HAER documentation for a selected group of bridges
• Investigating and preparing a summary regarding how other states have funded historic bridge programs and suggestions for creation of a new funding mechanism for Minnesota’s local historic bridges
The Bridge Reports compile and summarize historic and engineering information concerning the structures. It is important to note that this report indicates if a bridge is located within a known historic district, but it does not identify all known or potential historic properties. Potential impacts to adjacent or surrounding historic properties, such as archaeological sites or other structures must be considered. In order to identify other potential historic properties, owners should contact MnDOT CRU early in the project planning process. The reports also document the existing use and condition of the bridges along with assessments of the maintenance, stabilization and preservation needs of each structure, including cost estimates. The maintenance activities, along with regular structural inspections and anticipated bridge component replacements, are routine practices directed toward continued structure serviceability. Stabilization activities address immediate needs identified as necessary to maintain a bridge’s structural and historic integrity and serviceability. Preservation activities are near term or long term steps that need to be taken to preserve, and in some cases restore, a bridge’s structural and historic integrity and serviceability. In assessing preservation activities, a design life of 20 years or longer is typically considered. In addition to general restoration activities, and dependent on the severity of deterioration, preservation activities may include spot repair, disassembly and reassembly, or replacement of specific bridge components.
Recommendations within the Bridge Reports are consistent with the Secretary of the Interior’s Standards for the Treatment of Historic Properties (Standards). The Standards are basic principles created to help preserve the distinct character of a historic property and its site, while allowing for reasonable changes to meet new engineering standards and codes. The Standards recommend repairing, rather than replacing,
JUNE 2017 Project Introduction I - 1 Minnesota Department of Transportation (MnDOT) Local Historic Bridge Report
I – Project Introduction Bridge Number: Milwaukee Road Railroad Bridge
deteriorated features whenever possible. The Standards apply to historic properties of all periods, styles, types, materials and sizes and encompass the property’s location and surrounding environment.
The Standards were developed with historic buildings in mind and cannot be easily applied to historic bridges. The Virginia Transportation Research Council (Council) adapted the Standards to address the special requirements of historic bridges. They were published in the Council’s 2001 Final Report: A Management Plan for Historic Bridges in Virginia, The Secretary’s Standards with Regard to Repair, Rehabilitation, and Replacement Situations, and provide useful direction for undertaking maintenance, repair, rehabilitation, and replacement of historic bridges and are included in the Appendix to this report.
Existing bridge data sources typically available for Minnesota bridges were gathered for the study. These sources include: • Structure Information Management System (SIMS): system used by MnDOT to manage its inventory of bridges statewide
• The current MnDOT Structure Inventory Report and MnDOT Bridge Inspection Report. Reports are available for the majority of the bridges (not available for bridges in private ownership or bridges that are not tracked in SIMS)
• Database and inventory forms resulting from Phase II of the Minnesota Local Historic Bridge Study and other prior historic bridge studies as incorporated into the database
• Existing historic context studies for bridges in Minnesota, including Reinforced-Concrete Highway Bridges in Minnesota, 1900-1945; Minnesota Masonry-Arch Highway Bridges, 1870-1945; Iron and Steel Bridges in Minnesota, 1873-1945; and Minnesota Bridges 1955-1970
• Field investigations documenting the general structural condition and determining character- defining features
Additional data sources researched and gathered for some of the bridges as available also included: • Files and records at MnDOT and Local Owner offices
• Original bridge construction plans, rehabilitation plans, and maintenance records of local owners
• Files and documents available at the SHPO office, including previous inventory forms, determinations of eligibility, studies, and compliance documents
• Existing historic and documentary material related to the National Register-eligible bridges
The Appendix contains the following: A Glossary explaining structural and historic preservation terms used in this report, the Guidelines for Bridge Maintenance and Rehabilitation based on the Secretary of the Interior’s Standards, a list of engineering and historic documents available for this bridge, and copies of the MnDOT Structure Inventory and Bridge Inspection Reports current at the time of the report preparation.
The Bridge Report will provide the bridge owner and other interested parties with a comprehensive summary of the bridge condition and detailed information related to the historic nature of the bridge. This information will enable historic bridge owners to make informed decisions when planning for their historic properties.
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II – Historic Data Bridge Number: Milwaukee Road Railroad Bridge
This narrative is drawn from previous documents, as available for the subject bridge, which may include determination of eligibility (also known as Phase II evaluation), Minnesota Architecture/History Inventory Form, National Register nomination, Multiple Property Documentation Form, and/or applicable historic contexts. See Sources for details on which documents were used in compiling this Historic Data section.
Contractor Unknown
Designer/Engineer Unknown
Description
The Milwaukee Road Railroad Bridge historically carried the Chicago, Milwaukee, St. Paul & Pacific Railroad (Milwaukee Road) over Minnehaha Creek in Minnehaha Park, Minneapolis, Hennepin County, Minnesota. The bridge is located along the now partially-active railroad segment that runs northwest to southeast through southeast Minneapolis, starting south of East 27th Street. The bridge has a northwest to southeast alignment and is located in the northwest corner of Minnehaha Park, south of Godfrey Parkway. The Minnesota State Highway 55/Hiawatha Avenue Bridge over Minnehaha Creek is located directly to the west of this bridge. Directly to the east is the bridge carrying South Minnehaha Drive over Minnehaha Creek. This segment of Minnehaha Creek is characterized by gradual slopes on both sides of the creek’s embankments. Dense brush and deciduous trees line the creek. The northeast side of the creek is lined with coursed limestone retaining walls that abut directly with the bridge, extend to the east, and abut with the bridge that carries South Minnehaha Drive over Minnehaha Creek.
This circa 1930 bridge is a single-span, reinforced-concrete, filled-spandrel, segmental-arch structure. Research did not uncover bridge plans or inspection files; however, a circa 1940 track profile sheet from the Milwaukee Road Archives notes that this is “Bridge S-338 – 13x30 Arch.” The structure span length is approximately 30 feet. The substructure is comprised of cast-in-place, reinforced-concrete abutments and wingwalls.
The superstructure is comprised of a cast-in-place, reinforced-concrete segmental-arch executed in a simple classical revival architectural style. The arch ring replicates voussoirs that are similar in size and shape to the arch ring in the neighboring stone masonry arch Bridge 4559. Engaged concrete pilasters flank the arch. The closed concrete spandrel walls terminate at the deck and are topped with a concrete cap. The concrete cap is slightly taller than the deck. The deck features a centrally located single-track that is comprised of steel rails, wood ties, and minimal ballast. There is significant vegetation growing on the deck, including grasses and brush, and much of the track is hidden from view due to the vegetation growth. Four metal-encased utility lines are bolted to the spandrel walls and abutments of the southwest elevation, and run horizontally the length of the bridge, directly above the arch. With the exception of the addition of the utility lines, the bridge does not exhibit any obvious alterations.
Significance
The Milwaukee Road Railroad Bridge is the second bridge constructed in this location; however, research at multiple repositories did not reveal a construction date for this current structure, nor provide information on changes or alterations over time. The stylized voussoirs around the arch are somewhat reminiscent of the Art Deco style popular in the 1920s and 1930s. As such this bridge was likely constructed circa 1930.
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II – Historic Data Bridge Number: Milwaukee Road Railroad Bridge
The first railroad bridge in this location was constructed in 1864-1865 by the Minnesota Central Railway Company, when they constructed a line between Minneapolis and Faribault. The Minnesota Central Railway Company was purchased by the McGregor Western Railway Company in 1867, which became part of a mass consolidation of several railway companies under the Milwaukee & St. Paul Railway Company (M&StP) that same year. To reflect the completion of a line between Milwaukee and Chicago in 1872, the M&StP became the Chicago, Milwaukee & St. Paul Railway Company (CM&StP) in 1874. After extending tracks to Seattle and Tacoma, Washington, the railroad made a final name change to the Chicago, Milwaukee, St. Paul & Pacific Railway Company (CMStP&P) in 1926.
The CMStP&P was one of the major granger railroads (railroads that mainly hauled the produce of farmers) and was instrumental in hauling large volumes of agriculture produce and livestock from Minnesota, South Dakota, and Northern Iowa into the Twin Cities, as well as processed food and manufactured goods out of the Twin Cities. Commonly known as the “Milwaukee Road,” it remained the CMStP&P until 1985 when the Soo Line Corporation bought the bankrupt company; in turn, Soo Line was bought out by Canadian Pacific (CP) in the early 1990s.
The exact date the railroad abandoned this part of the line is not known; however, the 2.8 miles between the Fort Snelling Switch and Mendota, located approximately two miles south of this bridge, were abandoned in 1958, according to Milwaukee Road histories. Additionally, the Minnehaha Depot, located just to the south of this bridge, was given to the Minnesota Historical Society by the Milwaukee Road in 1963. Therefore, it is likely that this segment of the line was abandoned between the late 1950s and early 1960s. Using present-day aerial photographs, it appears that the segment of this line between East 27th Street and East 45th Street is still active and maintained. This bridge is located south of East 45th Street where the tracks have been abandoned. Although the linear corridor is still visible and tracks appear to remain in many locations, much of the trackage has become overgrown.
This bridge is located within the Minnehaha Park segment of the Grand Rounds. In 1883, the Minneapolis Board of Park Commissioners hired Horace W. S. Cleveland to create a series of parks and interconnected parkways to connect and preserve existing natural features in and near the city. Known as the Grand Rounds, the series of parkways encircling the city and connecting lakes, rivers, creeks, and other natural features, continued to be developed and expanded throughout the twentieth century. Minnehaha Park is located within the boundaries of the Grand Rounds. In 1885, the Minnesota Legislature authorized the creation of a park at Minnehaha Falls and a commission was established to select and appraise land to be purchased for the park. The commission selected 123 acres of land around the falls and along Minnehaha Creek to the Mississippi River. However, due to legal disputes with nearby land owners, the Legislature did not authorize the purchase of the land until 1889 (Minneapolis Veterans Home 1992; Smith 2008:167-168). In 2012, the Grand Rounds were determined eligible for the National Register of Historic Places (NRHP). This bridge is located within the boundaries of the Grand Rounds Historic District and is considered a contributing element to the determined eligible district.
The abandoned Milwaukee Road Railroad Bridge remains in its original location over the Minnehaha Creek in South Minneapolis. As such, the bridge retains excellent integrity of location. It also retains good integrity of setting as the segment of Minnehaha Park through which it passes is largely undeveloped. Some spalling on the curbing has taken place, and utility lines attached to the southwest elevation
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II – Historic Data Bridge Number: Milwaukee Road Railroad Bridge
obscure some of the decorative arch, but it does not appear that any significant changes have otherwise been made to the design and appearance of the bridge. Therefore, the bridge retains good integrity of design, materials, and workmanship. Since the rail line has been abandoned, vegetation and trees have been allowed to grow over the deck, minimally affecting its integrity of feeling and association. Overall, the bridge retains sufficient historic integrity.
The Milwaukee Road Railroad Bridge is recommended as not eligible for the NRHP under Criterion A and Criterion C in the area of Engineering as an example of a reinforced concrete railroad bridge because it does not meet the registration requirements outlined within the Railroads in Minnesota, 1862-1956 Multiple Property Documentation Form (MPDF), which references use of the Reinforced-Concrete Bridges in Minnesota, 1890-1945 MPDF. However, the bridge is significant as a contributing element to the determined eligible Grand Rounds Historic District. Its period of significance is c.1930, which corresponds with the bridge’s estimated construction date.
The Milwaukee Road Railroad Bridge is located along a segment of the CMStP&P that has not been evaluated as a railroad corridor historic district. Evaluation of the railroad corridor as a historic district, and therefore the bridge’s contributing and/or noncontributing status within the linear historic district, is outside of the scope of this project.
Historic Context Railroads in Minnesota, 1862-1956 Reinforced Concrete Highway Bridges in Minnesota, 1890-1945
National Register Status Contributing to Eligible Historic District
Criterion A Significance N/A
Criterion C Significance N/A
Historic District Grand Rounds
SHPO inventory number HE-MPC-1737
Sources Used to Compile Section II -- Historic Data
Field inspection by Mead & Hunt, Inc. November 25, 2015
Frame, Robert, III 1988 National Register of Historic Places Multiple Property Documentation Form: Reinforced-Concrete Highway Bridges in Minnesota, 1900-1945. Prepared by Dr. Robert M. Frame III. On file at the Minnesota Historic Preservation Office, St. Paul, Minnesota.
Google Earth 2015 Aerial Photography of Minneapolis. Electronic document, https://www.google.com/maps/, accessed February 8, 2016.
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II – Historic Data Bridge Number: Milwaukee Road Railroad Bridge
Hess Roise and Company 2008 Minnesota Historic Properties Inventory Form: HE-MPC-01737. On file at the Minnesota Historic Preservation Office, St. Paul, Minnesota.
Luecke, John C. 1988 Dreams, Disasters and Demise: The Milwaukee Road in Minnesota. Grenadier Publications, Eagan, Minnesota.
Milwaukee Road Archives Circa 1940. Mainline-Mendota to Minneapolis Track Sheet. On file at the Milwaukee Road Archives, Milwaukee Public Library, Milwaukee, Wisconsin.
Minneapolis Veterans Home 1992 History of the Minneapolis Veterans Home. Minneapolis Veterans Home, Minneapolis, Minnesota.
Minnesota Historical Society Minnehaha Depot History. Electronic document, http://sites.mnhs.org/historic-sites/minnehaha- depot/history, accessed December 23, 2015.
Prosser, Richard S. 1966 Rails to the North Star. Dillon Press, Minneapolis, Minnesota.
Roise, Charlene, Stephanie K. Atwood, Marjorie Pearson 2012 Draft National Register of Historic Places Registration Form: Grand Rounds Historic District. Prepared by Hess, Roise and Company. On file at the State Historic Preservation Office, St. Paul, Minnesota.
Schafer, Mike 1996 Classic American Railroads, Volume I. MBI Publishing Company, St. Paul, Minnesota.
Schmidt, Andrew J., Daniel R. Pratt, Andrea C. Vermeer, and Betsy H. Bradley 2013 National Register of Historic Places Multiple Property Documentation Form: Railroads in Minnesota, 1862-1956. Prepared by Summit Envirosolutions, Inc. and ARCH3, LLC. On file at the State Historic Preservation Office, St. Paul, Minnesota.
Smith, David C. 2008 Parks, Lakes, Trails and so much more: an overview of the historic of MPRB properties. Minneapolis Park and Recreation Board, 2008.
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II – Historic Data Bridge Number: Milwaukee Road Railroad Bridge
Character-Defining Features
Character-defining features are prominent or distinctive aspects, qualities, or characteristics of a historic property that contribute significantly to its physical character. Features may include materials, engineering design, and structural and decorative details. Often, the character-defining features include important historic fabric. However, historic fabric can also be found on other elements of a bridge that have not been noted as character-defining. For this reason, it is important to consider both character- defining features and the bridge’s historic fabric when planning any work.
Feature 1: Design of arch ring with stylized voussoirs.
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II – Historic Data Bridge Number: Milwaukee Road Railroad Bridge
Feature 2: Bridge location within the Grand Rounds.
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III – Bridge Data Bridge Number: Milwaukee Road Railroad Bridge
Date of Construction (remodel) c. 1930 Common Name (if any) Milwaukee Road Railroad Bridge Location Feature Carried: Abandoned Railroad Feature Crossed: Minnehaha Creek County: Hennepin Ownership: Minneapolis Park and Recreation Board Structure Data Data Current (as of): June 2016 Main Span Type: 112 - Concrete Arch Main Span detail: Filled Spandrel Substructure Type - Foundation Type: Abutment: 1-Concrete – 0-Unknown Piers: N-Not Applicable – N-Not Applicable
Roadway Characteristics Lane Widths: N/A-No Approach Shoulder Width: N/A-No Approach Shoulders Paved or Unpaved: N/A-No Approach Roadway Surfacing: N/A-No Approach
Number of Crashes reported in MnMCAT within 500 feet of Bridge Site N/A-No Roadway
Location of Plans N/A Plans Available No Plan Available
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IV – Existing Conditions/Recommendations Railroad Bridge
Existing Conditions
Available information, as detailed in the Project Introduction section, concerning the Milwaukee Road Railroad Bridge was reviewed prior to visiting the bridge site. The site visit was conducted to establish the following: 1. General condition of structure 2. Conformation to available extant plans 3. Current use of structure 4. Roadway/pedestrian trail geometry and alignment (as applicable) 5. Bridge geometry, clearances and notable site issues
General Bridge Description
The Milwaukee Road Railroad Bridge is a single span, cast-in-place concrete arch bridge spanning 30 feet over Minnehaha Creek located in Minneapolis in Hennepin County. The structural arch and its headwalls and wingwalls are comprised of cast-in-place reinforced concrete. The arch rises from cast-in- place concrete abutments. All concrete surfaces have a board-formed finish. The underside of the arch reaches a height of approximately 12 feet 2 inches above existing grade. The top of the arch is earth filled with an abandoned railroad track centered between headwalls. The bridge is 18 feet 8 inches wide (out- to-out) and the interior width between headwalls is 14 feet. There are four conduits attached to the west face of the bridge wingwalls and headwall.
The Milwaukee Road Railroad Bridge is in poor condition overall. The most significant defects of the bridge structure include spalling, cracking and delamination of the concrete arch, headwalls, wingwalls, and substructures; as well as heavy tree and vegetation growth on the surface of the fill between the headwalls and wingwalls.
Serviceability Observations
The bridge is currently closed to railroad traffic, but exhibits signs of footpaths formed due to pedestrian traffic. There is not a managed trail system connecting to the bridge and there is no closure signing or closure fencing at the bridge site to discourage foot traffic.
Condition Observations
Access to some critical portions of the structure was limited. All observations and quantity estimates were made from ground level, either on the bridge slopes, in shallow areas of the stream or from the bridge deck. As such, the condition observations and recommendations that follow in this report are general in nature. A more in-depth inspection utilizing the appropriate access equipment to permit hands-on inspection should be undertaken to better quantify required repairs prior to refining a rehabilitation scope and undertaking any rehabilitation work. All condition observations herein for inaccessible elements are derived from a visual inspection.
Reinforced-Concrete Abutments
The reinforced-concrete abutments are in fair condition. Both abutments have deteriorated concrete along the waterline ranging from 1 to 4 inches deep and 1 to 2 feet high, with one location on the north
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IV – Existing Conditions/Recommendations Railroad Bridge
abutment showing exposed reinforcement. There is one notable area of deep scour, approximately 8 inches deep by 1 foot long, located near the southeast abutment corner.
Reinforced-Concrete Arch
The reinforced-concrete arch is in fair condition. There are some minor longitudinal cracks in the arch with no significant leaching or efflorescence. There are approximately five notable areas of concrete spalls with exposed reinforcement. The majority of the spalled areas are located along the exterior edges adjacent to the headwalls.
Reinforced-Concrete Headwalls
The reinforced-concrete headwalls are in poor condition. There is random cracking throughout the west headwall pilasters and a vertical crack below the horizontal construction joint at the center of the southeast pilaster. There are trees growing along the east headwall pilasters from the ground line to the top of the pilasters. There are various areas of concrete spalls in both headwalls with the most significant loss of concrete located on the top cap/coping.
Reinforced-Concrete Wingwalls
The reinforced-concrete wingwalls are in poor condition. There are large areas of concrete deterioration, spalling and delamination in all four corners of the bridge. All wingwalls have random cracking throughout their front faces with efflorescence present.
Paint and Graffiti
There is extensive graffiti on the bridge, especially in the locations nearest the stream. There are various areas of all concrete elements of the structure (headwalls, wingwalls, arches and abutments) that are covered with graffiti or painted to cover previous graffiti; totaling approximately 550 square feet.
Earth-Filled Surface and Railroad Tracks
The arch is earth filled with heavy tree and vegetation growth over the entire length of the bridge between headwalls, wingwalls and abandoned railroad tracks. There are no railings or barriers on the bridge. The earth fill elevation is approximately 2 inches below top of headwalls for the full length of bridge.
Slopes
All four slopes are steep with minor erosion, but currently appear stable due to adequate tree growth and root systems.
Approach/Waterway Observations The approaches at each end of bridge include heavy tree and vegetation growth. The east downstream banks include a stone retaining wall extending from the pilaster faces to the adjacent bridge abutments along the edge of creek.
Date of Engineering Site Visit by LHB June 8, 2016
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IV – Existing Conditions/Recommendations Railroad Bridge
Condition 1: East elevation
Condition 2: West elevation
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IV – Existing Conditions/Recommendations Railroad Bridge
Condition 3: North abutment
Condition 4: North abutment concrete deterioration at waterline
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IV – Existing Conditions/Recommendations Railroad Bridge
Condition 5: Longitudinal arch cracks, north side
Condition 6: Southeast corner reinforced-concrete arch spall with exposed reinforcement
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IV – Existing Conditions/Recommendations Railroad Bridge
Condition 7: Southwest corner reinforced-concrete arch spalled and delaminated concrete
Condition 8: Southeast pilaster random cracks
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IV – Existing Conditions/Recommendations Railroad Bridge
Condition 9: Southeast pilaster vertical crack below construction joint
Condition 10: Northeast tree growth along pilaster and coping
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IV – Existing Conditions/Recommendations Railroad Bridge
Condition 11: West headwall concrete coping deterioration, note conduit attached to bridge
Condition 12: Southwest wingwall concrete deterioration
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IV – Existing Conditions/Recommendations Railroad Bridge
Condition 13: Southeast wingwall cracks with efflorescence
Condition 14: Top of bridge vegetation and abandoned railroad tracks
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IV – Existing Conditions/Recommendations Railroad Bridge
Condition 15: Northwest slope
Condition 16: Southwest slope
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IV – Existing Conditions/Recommendations Railroad Bridge
Condition 17: Northeast slope, note stone retaining wall
Condition 18: Southeast slope, note stone retaining wall
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IV – Existing Conditions/Recommendations Railroad Bridge
Overall Recommendations
The bridge is currently closed with an abandoned railroad track over the bridge and no managed trail at this crossing. The recommendations that follow assume the structure’s use will remain the same.
Recommended Stabilization Activities
1. Since there is not a compliant safety rail over the bridge, it is recommended that closure signage and fencing be installed at each end of the bridge to discourage pedestrian traffic over the structure.
2. Clear trees and vegetation on the top of the bridge fill surface and on bridge slopes along the wingwalls to prevent moisture and root systems from damaging the concrete.
Recommended Preservation Activities
Reinforced-Concrete Abutments
Repairs to the abutments should include concrete repair to the spalled/ scoured regions noted near the waterline. The repair will consist of selective removal of deteriorated concrete to sound concrete. Following concrete removal, any exposed reinforcement bars should be cleaned and epoxy coated. Following repair of any reinforcement, and to maintain historic integrity, the concrete should be replaced with concrete of color, composition, forming and finish to match the original concrete. Due to the extensive scouring of the abutments at the waterline, it is recommended to construct a full length underpinning wall along each abutment. A temporary stream diversion would be needed in order to facilitate the underpinning work.
Reinforced-Concrete Arch
Spalls in the arch are recommended to be repaired. Concrete repair should be done in a manner similar to that described in the Reinforced-Concrete Abutments section above.
Reinforced-Concrete Headwalls
Spalls in the headwalls and top cap are recommended to be repaired. Concrete repair should be done in a manner similar to that described in the Reinforced-Concrete Abutments section above. Trees growing at the east side pilasters should be removed to help protect the concrete from further damage caused by tree trunks and roots.
Reinforced-Concrete Wingwalls
Spalls in the wingwalls are recommended to be repaired. Concrete repair should be done in a manner similar to that described in the Reinforced-Concrete Abutments section above.
Paint and Graffiti
The graffiti/ painted areas should be removed down to original concrete with a process that is gentle enough to remove the paint without compromising the existing concrete surfaces such as use of micro-
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IV – Existing Conditions/Recommendations Railroad Bridge
abrasive blasting performed by a qualified and skilled operator. To maintain historic integrity, test panels, in inconspicuous locations of the structure, should be prepared to assure the method used does not abrade, discolor or in any way compromise the existing concrete surface. It is not recommended to use anti-graffiti coatings unless testing is performed to show their efficiency and that they will not harm or change the appearance of the underlying concrete.
Earth-Filled Surface and Railroad Tracks
The heavy tree and vegetation growth over the entire bridge is recommended to be cleared and grubbed to help protect the concrete from further damage caused by the vegetation’s root system. Once the vegetation is removed from the top of bridge, it is recommended that a pedestrian fence/railing be added for safety due to the current lack of a railing/ barrier. Even though the railroad is abandoned and there is no pedestrian trail connected, the bridge appears to already carry foot traffic and will become more visible after clearing, which may attract more pedestrians to utilize the structure. The fence/railing should be installed in the ground alongside the headwalls and wingwalls. The design of the fence/railing should liken other fence or railing found within the Grand Rounds Historic District, but should not convey the sense that it is part of the historic fabric of the bridge. This fence/railing should remain reversible and should not damage or connect to the concrete headwalls and wingwalls. Should a fence/railing be installed along the bridge walls, the closure fencing and signage recommended in the Recommended Stabilization Activities above may be left in place or removed, at the discretion of the owner. No cost has been associated with fencing or signage removal.
Slopes
The slopes are in fair condition. No recommended preservation activities were recommended at the time of inspection.
Recommended Annual Maintenance Activities
There are no maintenance activities recommended for the bridge at this time.
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V – Projected Costs Bridge Number: Milwaukee Road Railroad Bridge
Summarized Maintenance, Stabilization and Preservation Construction Cost Estimates
It is important to recognize that the work scope and cost estimates presented herein are based on a limited level assessment of the existing structure. In moving forward with future project planning, it will be essential to undertake a detailed structure assessment addressing the proposed work for the structure. It is also important that any future preservation work follow applicable preservation standards with emphasis to rehabilitate and repair in-place structure elements in lieu of replacement. This includes elemen ts that are preliminarily estimated for replacement within the work scope of this report. Only through a thorough review of rehabilitation and repair options and comprehensive structural and historic assessment can a definitive conclusion for replacement of historic fabric be formed.
The opinions of probable construction and administrative costs provided below are presented in 2016 dollars. These costs were developed without benefit of a detailed, thorough bridge inspection, bridge survey or completion of preliminary design for the estimated improvements. The estimated costs represent an opinion based on background knowledge of historic unit prices and comparable work performed on other structures. The opinions of cost are intended to provide a programming level of estimated cost. These costs will require refinement and may require significant adjustments as further analysis is completed in determining the course of action for future structure improvements. A 20 percent contingency and 7 percent mobilization allowance has been included in the construction cost estimates.
Administrative and engineering costs are also presented below. Engineering and administrative costs are also to be interpreted as programming level only. Costs can be highly variable and are dependent on structure condition, intended work scope, project size and level of investigative, testing and documentation work necessary. Additional studies, evaluation, and historic consultation costs not exclusively called out may also be incurred on a case-by-case basis.
Maintenance, Stabilization, and Preservation Costs (refer to the work item breakdown on the next page)
Opinion of Annual Cost- Maintenance Activities: $ 0
Opinion of Construction Cost- Stabilization Activities: $ 7,000
Opinion of Construction Cost- Preservation Activities: $ 242,050
Estimated Preliminary Design, Final Design, Construction Administration Costs
Preliminary Design and Assessment $ 6,000
Final Design and Plans $ 35,000
Construction Administration $ 20,000
JUNE 2017 Projected Costs V - 23 Minnesota Department of Transportation (MnDOT) Local Historic Bridge Report
V – Projected Costs Bridge Number: Milwaukee Road Railroad Bridge
MAINTENANCE, STABILIZATION & PRESERVATION COST ESTIMATE (2016 DOLLARS) Milwaukee Road Railroad Bridge (HE-MPC-1737) April 19, 2017 ESTIMATED QUANTITIES AND COST ITEM ITEM UNIT QUANTITY UNIT COST TOTAL ESTIMATE NO. MAINTENANCE COSTS
NO MAINTENANCE ACTIVITIES RECOMMENDED
20% CONTINGENCY LUMP SUM 1 $0.00 $0.00
ESTIMATED MAINTENANCE COSTS $0.00 STABILIZATION COSTS
1 INSTALL CLOSURE SIGNAGE AND FENCING LUMP SUM 1 $5,000.00 $5,000.00 2 CLEAR TREES & VEGETATION FROM DECK AND SLOPES LUMP SUM 1 $800.00 $800.00
20% CONTINGENCY LUMP SUM 1 $1,200.00 $1,200.00
ESTIMATED STABILIZATION COSTS $7,000.00 PRESERVATION COSTS
MOBILIZATION @ 7% LUMP SUM 1 $14,000.00 $14,000.00
1 CONCRETE UNDERPIN WALL - ABUTMENTS LIN FT 40 $400.00 $16,000.00 2 DEWATERING & STREAM DIVERSION LUMP SUM 1 $20,000.00 $20,000.00 3 CONCRETE REPAIR - ARCH SQ FT 30 $300.00 $9,000.00 4 CONCRETE REPAIR - HEADWALLS SQ FT 330 $250.00 $82,500.00 5 CONCRETE REPAIR - WINGWALLS SQ FT 130 $200.00 $26,000.00 6 GRAFFITI REMOVAL SQ FT 550 $25.00 $13,750.00 7 REMOVE TREE EACH 2 $800.00 $1,600.00 8 PEDESTRIAN FENCE LIN FT 140 $130.00 $18,200.00
20% CONTINGENCY LUMP SUM 1 $41,000.00 $41,000.00
ESTIMATED PRESERVATION COSTS $242,050.00
JUNE 2017 Projected Costs V - 24 Minnesota Department of Transportation (MnDOT) Local Historic Bridge Report
Appendices Bridge Number: Milwaukee Road Railroad Bridge
Appendix A. Glossary
JUNE 2017 Appendices - 25
Glossary
Abutment – Component of bridge substructure at either end of bridge that transfers load from superstructure to foundation and provides lateral support for the approach roadway embankment.
Appraisal ratings – Five National Bridge Inventory (NBI) appraisal ratings (structural evaluation, deck geometry, under-clearances, waterway adequacy, and approach alignment, as defined below), collectively called appraisal ratings, are used to evaluate a bridge’s overall structural condition and load- carrying capacity. The evaluated bridge is compared with a new bridge built to current design standards. Ratings range from a low of 0 (closed bridge) to a high of 9 (superior). Any appraisal item not applicable to a specific bridge is coded N.
Approach alignment – One of five NBI inspection ratings. This rating appraises a bridge’s functionality based on the alignment of its approaches. It incorporates a typical motorist’s speed reduction because of the horizontal or vertical alignment of the approach.
Character-defining features – Prominent or distinctive aspects, qualities, or characteristics of a historic property that contribute significantly to its physical character. Features may include structural or decorative details and materials.
Condition, fair – A bridge or bridge component of which all primary structural elements are sound, but may have minor deterioration, section loss, cracking, spalling, or scour.
Condition, good – A bridge or bridge component which may have some minor deficiencies, but all primary structural elements are sound.
Condition, poor – A bridge or bridge component that displays advanced section loss, deterioration, cracking, spalling, or scour.
Condition rating – Level of deterioration of bridge components and elements expressed on a numerical scale according to the NBI system. Components include the substructure, superstructure, deck, channel, and culvert. Elements are subsets of components, e.g., piers and abutments are elements of the component substructure. The evaluated bridge is compared with a new bridge built to current design standards. Component ratings range from 0 (failure) to 9 (new) or N for (not applicable); elements are rated on a scale of 1-3, 1-4 or 1-5 (depending on the element type and material). In all cases condition state 1 is the best condition with condition state 3, 4 or 5 being the worst condition. In rating a bridge’s condition, MnDOT pairs the NBI system with the newer and more sophisticated Pontis element inspection information, which quantifies bridge elements in different condition states and is the basis for subsequent economic analysis.
Corrosion – The general disentegration of metal through oxidation.
Cutwater – The wedge-shaped end of a bridge pier, designed to divide the current and break up ice.
Decay – Deterioration of wood as a result of fungi feeding on its cell walls.
Delamination – Surface separation of concrete, steel, glue laminated timber plies etc. into layers.
Deck geometry – One of five NBI appraisal ratings. This rating appraises the functionality of a bridge’s roadway width and vertical clearance, taking into account the type of roadway, number of lanes, and ADT.
Deficiency – The inadequacy of a bridge in terms of structure, serviceability, and/or function. Structural deficiency is determined through periodic inspections and is reflected in the ratings that are assigned to a bridge. Service deficiency is determined by comparing the facilities a bridge provides for vehicular, bicycle, and pedestrian traffic with those that are desired. Functional deficiency is another term for functionally obsolete (see below). Remedial activities may be needed to address any or all of these deficiencies.
Deficiency rating – A nonnumeric code indicating a bridge’s status as structurally deficient (SD) or functionally obsolete (FO). See below for the definitions of SD and FO. The deficiency rating status may be used as a basis for establishing a bridge’s eligibility and priority for replacement or rehabilitation.
Design exception – A deviation from federal design and geometric standards that takes into account environmental, scenic, aesthetic, historic, and community factors that may have bearing upon a transportation project. A design exception is used for federally funded projects where federal standards are not met. Approval requires appropriate justification and documentation that concerns for safety, durability, and economy of maintenance have been met.
Design load – The usable live-load capacity that a bridge was designed to carry, expressed in tons according to the AASHTO allowable stress, load factor, or load resistance factor rating methods. An additional code was recently added to assess design load by a rating factor instead of tons. This code is used to determine if a bridge has sufficient strength to accommodate traffic load demands. A bridge that is posted for load restrictions is not adequate to accommodate present or expected legal truck traffic.
Deterioration – Decline in condition of surfaces or structure over a period of time due to chemical or physical degradation.
Efflorescence – A deposit on concrete or brick caused by crystallization of carbonates brought to the surface by moisture in the masonry or concrete.
Extant – Currently or actually existing.
Extrados – The upper or outer surfaces of the voussoirs which compose the arch ring. Often contrasted with intrados.
Footing – The enlarged, lower portion of a substructure which distributes the structure load either to the earth or to supporting piles.
Fracture Critical Members – Tension members or tension components of bending members (including those subject to reversal of stress) whose failure would be expected to result in collapse of the bridge.
Functionally obsolete – The Federal Highway Administration (FHWA) classification of a bridge that does not meet current or projected traffic needs because of inadequate horizontal or vertical clearance, inadequate load-carrying capacity, and/or insufficient opening to accommodate water flow under the bridge. An appraisal rating of 3 or less for deck geometry, underclearance, approach alignment, structural evaluation or waterway adequacy will designate a bridge as functionally obsolete.
Gusset plate – A plate that connects the horizontal and vertical members of a truss structure and holds them in correct position at a joint.
Helicoidal – Arranged in or having the approximate shape of a flattened coil or spiral.
Historic fabric – The material in a bridge that was part of original construction or a subsequent alteration within the historic period of the bridge (i.e., more than 50 years old). Historic fabric is an important part of the character of the historic bridge and the removal, concealment, or alteration of any historic material or distinctive engineering or architectural feature should be avoided if possible. Often, the character- defining features include important historic fabric. However, historic fabric can also be found on other elements of a bridge that have not been noted as character-defining.
Historic bridge – A bridge that is listed in, or eligible for listing in, the National Register of Historic Places.
Historic integrity – The authenticity of a bridge’s historic identity, evidenced by the survival and/or restoration of physical characteristics that existed during the bridge’s historic period. A bridge may have integrity of location, design, setting, materials, workmanship, feeling, and association.
Inspections – Periodic field assessments and subsequent consideration of the fitness of a structure and the associated approaches and amenities to continue to function safely.
Intrados – The innner or lower surface of an arch. Often contrasted with extrados.
Inventory rating – The load level a bridge can safely carry for an indefinite amount of time expressed in tons or by the rating factor described in design load (see above). Inventory rating values typically correspond to the original design load for a bridge without deterioration.
Keystone – Wedge-shaped stone, or voussoir, at the crown of an arch.
Load Rating – The determination of the live load carrying capacity of a bridge using bridge plans and supplemented by field inspection.
Maintenance – Work of a routine nature to prevent or control the process of deterioration of a bridge.
Minnesota Historical Property Record – A documentary record of an important architectural, engineering, or industrial site, maintained by the Minnesota Historical Socitety as part of the state’s commitment to historic preservation. MHPR typically includes large-format photographs and written history, and may also include historic photographs, drawings, and/or plans. This state-level documentation program is modeled after a federal program known as the Historic American Buildings Survey/Historic American Engineering Record (HABS/HAER).
National Bridge Inventory – Bridge inventory and appraisal data collected by the FHWA to fulfill the requirements of the National Bridge Inspection Standards (NBIS). Each state maintains an inventory of its bridges subject to NBIS and sends an annual update to the FHWA.
National Bridge Inspection Standards – Federal requirements for procedures and frequency of inspections, qualifications of personnel, inspection reports, and preparation and maintenance of state bridge inventories. NBIS applies to bridges located on public roads.
National Register of Historic Places – The official inventory of districts, sites, buildings, structures, and objects significant in American history, architecture, archaeology, and culture, which is maintained by the Secretary of the Interior under the authority of the National Historic Preservation Act of 1966 (as amended).
Non-vehicular traffic – Pedestrians, non-motorized recreational vehicles, and small motorized recreational vehicles moving along a transportation route that does not serve automobiles and trucks. Includes bicycles and snowmobiles.
Operating rating – Maximum permissible load level to which a bridge may be subjected based on a specific truck type, expressed in tons or by the rating factor described in design load (see above).
Pack rust – Rust forming between adjacent steel surfaces in contact which tends to force the surfaces apart due to the increase in steel volume.
Pier – A substructure unit that supports the spans of a multi-span superstructure at an intermediate location between its abutments.
Pointing – The compaction of mortar into the outermost portion of a joint and the troweling of its exposed surface to secure water tightness and/ or desired architectural effect (when replacing deteriorated mortar).
Pony truss – A through bridge with parallel chords and having no top lateral bracing over the deck between the top chords.
Posted load – Legal live-load capacity for a bridge which is associated with the operating rating. A bridge posted for load restrictions is inadequate for legal truck traffic.
Pontis – Computer-based bridge management system to store inventory and inspection data and assist in other bridge data management tasks.
Preservation – Preservation, as used in this report, refers to historic preservation that is consistent with the Secretary of the Interior’s Standards for the Treatment of Historic Properties. Historic preservation means saving from destruction or deterioration old and historic buildings, sites, structures, and objects, and providing for their continued use by means of restoration, rehabilitation, or adaptive reuse. It is the act or process of applying measures to sustain the existing form, integrity, and material of a historic building or structure, and its site and setting. MnDOT’s Bridge Preservation, Improvement and Replacement Guidelines describe preservation differently, focusing on repairing or delaying the deterioration of a bridge without significantly improving its function and without considerations for its historic integrity.
Preventive maintenance – The planned strategy of cost-effective treatments that preserve a bridge, slow future deterioration, and maintain or improve its functional condition without increasing structural capacity.
Reconstruction – The act or process of depicting, by means of new construction, the form, features, and detailing of a non-surviving site, landscape, building, structure, or object for the purpose of replicating its appearance at a specific period of time and in its historic location. Activities should be consistent with the Secretary of the Interior’s Standards for the Treatment of Historic Properties.
Rehabilitation – The act or process of returning a historic property to a state of utility through repair or alteration which makes possible an efficient contemporary use, while preserving those portions or features of the property that are significant to its historical, architectural, and cultural values. Historic rehabilitation, as used in this report, refers to implementing activities that are consistent with the Secretary of the Interior’s Standards for the Treatment of Historic Properties. As such, rehabilitation retains historic fabric and is different from replacement. MnDOT’s Bridge Preservation, Improvement and Replacement Guidelines describe rehabilitation and replacement in similar terms.
Restoration – The act or process of accurately depicting the form, features, and character of a property as it appeared at a particular period of time. Activities should be consistent with the Secretary of the Interior’s Standards for the Treatment of Historic Properties.
Ring stone – One of the separate stones of an arch that shows on the face of the headwall, or end of the arch. Also known as a voussoir.
Scaling – The gradual distentegration of a concrete surface due to the failure of the cement surface caused by chemical attack or freeze-thaw cycles or rebar too close to the surface and oxidizing from exposure to chlorides.
Scour – Removal of material from a river’s bed or bank by flowing water, compromising the strength, stability, and serviceability of a bridge.
Scour critical rating – A measure of a bridge’s vulnerability to scour (see above). MnDOT utilizes letter designations to represent specific descriptions of a bridges susceptibility and/ or present condition in regards to scour. Range in condition and scour susceptibility does not necessarily correlate alpha numerically to the MnDOT scour code letters so it is important to understand the specifc scour description for each MnDOT scour code. The scour codes and descriptions can be found in the ”MNDOT Bridge Inspection Field Manual”.
Section loss – Loss of a member’s cross sectional area and resulting strength usually by corrosion or decay.
Serviceability – Level of facilities a bridge provides for vehicular, bicycle, and pedestrian traffic, compared with current design standards.
Smart flag – Special Pontis inspection element used to report the condition assessment of a deficiency that cannot be modeled, such as cracks, section loss, and steel fatigue.
Spall – Depression in concrete caused by a separation of a portion of the surface concrete, revealing a fracture parallel with or slighty inclined to the surface.
Spring line – The imaginary horizontal line at which an arch or vault begins to curve. As example, the point of transition from the vertical face of an abutment to the start of arch curvature extending from abutment face.
Stabilization – The act or process of stopping or slowing further deterioration of a bridge by means of making minor repairs until a more permanent repair or rehabilitation can be completed.
Stringcourse – A horizontal band of masonry, generally narrower than other courses and sometimes projecting, that extends across the structure’s horizontal face as an architectural accent. Also known as belt course.
Structural evaluation – Condition rating of a bridge designed to carry vehicular loads, expressed as a numeric value and based on the condition of the superstructure and substructure, the inventory load rating, and the ADT.
Structurally deficient – Classification indicating NBI condition rating of 4 or less for any of the following: deck condition, superstructure condition, substructure condition, or culvert condition. A bridge is also classified as structurally deficient if it has an appraisal rating of 2 or less for its structural evaluation or waterway adequacy.. A structurally deficient bridge is restricted to lightweight vehicles; requires immediate rehabilitation to remain open to traffic; or requires maintenance, rehabilitation, or replacement.
Sufficiency rating – Rating of a bridge’s structural adequacy and safety for public use, and its serviceability and function, expressed on a numeric scale ranging from a low of 0 to a high of 100. It is a relative measure of a bridge’s deterioration, load capacity deficiency, or functional obsolescence. MnDOT may use the rating as a basis for establishing eligibility and priority for replacement or rehabilitation. Typically, bridges which are structurally deficient and have sufficiency ratings between 50 and 80 are eligible for federal rehabilitation funds and those which are structurally deficient with sufficientcy ratings of 50 and below are eligible for replacement.
Through truss – A bridge with parallel top and bottom chords and top lateral bracing with the deck generally near the bottom chord.
Under-clearances – One of five NBI appraisal ratings. This rating appraises the suitability of the horizontal and vertical clearances of a grade-separation structure, taking into account whether traffic beneath the structure is one- or two-way.
Variance – A deviation from State Aid Operations Statute Rules that takes into account environmental, scenic, aesthetic, historic, and community factors that may have bearing upon a transportation project. A design variance is used for projects using state aid funds. Approval requires appropriate justification and documentation that concerns for safety, durability and economy of maintenance have been met.
Vehicular traffic – The passage of automobiles and trucks along a transportation route.
Voussoir – One of the separate stones forming an arch ring; also known as a ring stone.
Waterway adequacy – One of five NBI appraisal ratings. This rating appraises a bridge’s waterway opening and passage of flow under or through the bridge, frequency of roadway overtopping, and typical duration of an overtopping event.
Minnesota Department of Transportation (MnDOT) Local Historic Bridge Report
Appendices Bridge Number: Milwaukee Rd RR Bridge
Appendix B. Guidelines for Bridge Maintenance and Rehabilitation based on the Secretary of the Interior’s Standards
JUNE 2017 Appendices - 33
The Secretary’s Standards with Regard to Repair, Rehabilitation, and Replacement Situations
Adapted from: Clark, Kenneth M., Grimes, Mathew C., and Ann B. Miller, Final Report, A Management Plan for Historic Bridges in Virginia, Virginia Transportation Research Council, 2001.
The Secretary of the Interior's Standards for the Treatment of Historic Properties, first codified in 1979 and revised in 1992, have been interpreted and applied largely to buildings rather than engineering structures. In this document, the differences between buildings and structures are recognized and the language of the Standards has been adapted to the special requirements of historic bridges.
1. Every reasonable effort shall be made to continue an historic bridge in useful transportation service. Primary consideration shall be given to rehabilitation of the bridge on site. Only when this option has been fully exhausted shall other alternatives be explored.
2. The original character-defining qualities or elements of a bridge, its site, and its environment should be respected. The removal, concealment, or alteration of any historic material or distinctive engineering or architectural feature should be avoided.
3. All bridges shall be recognized as products of their own time. Alterations that have no historic basis and that seek to create a false historic appearance shall not be undertaken.
4. Most properties change over time; those changes that have acquired historic significance in their own right shall be retained and preserved.
5. Distinctive engineering and stylistic features, finishes, and construction techniques or examples of craftsmanship that characterize an historic property shall be preserved.
6. Deteriorated structural members and architectural features shall be retained and repaired, rather than replaced. Where the severity of deterioration requires replacement of a distinctive element, the new element should match the old in design, texture, and other visual qualities and where possible, materials. Replacement of missing features shall be substantiated by documentary, physical, or pictorial evidence.
7. Chemical and physical treatments that cause damage to historic materials shall not be used. The surface cleaning of structures, if appropriate, shall be undertaken using the most environmentally sensitive means possible.
8. Significant archaeological and cultural resources affected by a project shall be protected and preserved. If such resources must be disturbed, mitigation measures shall be undertaken.
9. New additions, exterior alterations, structural reinforcements, or related new construction shall not destroy historic materials that characterize the property. The new work shall be differentiated from the old and shall be compatible with the massing, size, scale, and architectural features to protect the historic integrity of the property and its environment.
10. New additions and adjacent or related new construction shall be undertaken in such a manner that if removed in the future, the essential form and integrity of the historic property and its environment would be unimpaired.
Minnesota Department of Transportation (MnDOT) Local Historic Bridge Report
Appendices Bridge Number: Milwaukee Rd RR Bridge
Appendix C. Documents
JUNE 2017 Appendices - 36
Additional Electronic Data Bridge Milwaukee Road RR Bridge
Historic Data • Research
Local Data • N/A
MnDOT Reports • N/A
Photos • Milwaukee Road RR Bridge_M&H Photos • Milwaukee RR LHB 2016-06-08 • Milwaukee Road RR Bridge_Report Photos
Plans • N/A