Preserva on Assessment

Transcription

1 Preserva on Assessment For Walp Road over Nescopeck Creek BMS # Luzerne County PennDOT Engineering District 4 0 Final Report Dec 2017 Prepared by TranSystems for the Pennsylvania Department of Transporta on Environmental Policy and Development Sec on

2 BRIDGE LOCATION N BRIDGE LOCATION MAP Walp Road over Nescopeck Creek Sugarloaf Township, PA Source: PA Type 10 Map Luzerne County

3 RESOURCE LOCATION QUADRANGLE LOCATION SCALE SOURCE N 0ft 2000ft USGS 2010 Sybertsville, PA Walp Road over Nescopeck Creek Sugarloaf Township, Luzerne County, PA

4 Preservation Assessment for Walp Road Bridge PENNSYLVANIA METAL TRUSS BRIDGE PRESERVATION/REHABILITATION ASSESSMENT EVALUATIONS The purpose of this assessment is to provide a benchmark analysis in which to understand rehabilitation options based on existing conditions of the bridge and adjacent areas at the time of the analysis and the observed usage. This assessment is not a rehabilitation feasibility analysis, with purpose and need established, and a more in-depth study may be required if the project is to be further developed. The ability of this analysis to determine whether the bridge can be rehabilitated to meet project need is constrained by the fact that actual need is not established for this analysis and that data utilized is based on a field view, file research, and chance interviews with local parties. When actual project need is established, this information will be updated based on current field data. A final determination of whether rehabilitation can meet the project needs and would be considered feasible and prudent under Section 4(f) of the USDOT Act of 1966 will be determined during the NEPA/Section 4(f) process. BMS #: Bridge Key #: District: 4-0 County: Luzerne Township: Sugarloaf Owner: Luzerne County Maintenance: Luzerne County Location Information: 2.6 miles north of Conyngham and east of SR 0093 Bridge Name: Walp Road (T-342) over Nescopeck Creek Luzerne County Bridge No Type: Pony Truss Design: Pratt (pinned) Truss Materials: Steel Date: 1915 Alter/Rehab: 2004 Source: Inspection File Length: 62' Number Spans: 1 Deck Width: 16-4 (out-to-out dimension) Bridge Description The single span, 62'-long, wrought iron, pin-connected, Pratt pony truss bridge dated to 1915 is supported on masonry abutments. The bridge was built by Dean & Westbrook using Phoenix sections for the upper chords and inclined end posts and standard design Phoenix Company connecting pieces and bearings along with details that are Walp Road Bridge Assessment Page 1

5 Preservation Assessment for Walp Road Bridge particular to Dean & Westbrook. The roadway width is 16'- 2 and the overall deck width is 16'- 4. This is not a standardized design Pratt pony truss bridge, and it represents Dean & Westbrook s innovative thinking about features intended to provide a stronger bridge with the most economical use of material. The verticals are composed of angles with lacing. Pin plates are used to make their connection at the cast iron upper chord connecting pieces. The deep, built up floorbeams are framed into the bottom portion of the verticals above the eyebar lower chords. There are punched pin holes in each vertical for the lower panel point connection. Placing floorbeams above the lower chords is not common in Pratt pony truss bridges. A triangular-shaped riveted outrigger is present at both ends of each floorbeam that meets the vertical at about its midpoint. The diagonals are eyebars, and the counters are bar stock and Dean & Westbrook s cast open loop heads. All but one of the original pipe railings have been lost, replaced by a steel cable set inside the truss lines. The deck is timber planks, and the abutments and wingwalls are fieldstone. NR Eligibility Status: Eligible (SHPO 1988 Finding) under Criterion C for technological significance. Historic Preservation Priority: High (see Protocols for Levels of Priority located at Historic Preservation Priority Justification: Although there is no plaque on the pin connected 1915 Pratt pony truss bridge with Phoenix section upper chords and inclined end posts, it has the same distinctive details and design variations as (Bridge Key No ) that has a plaque identifying it as built in 1889 by Dean & Westbrook, Engineers and Contractors. Dean & Westbrook were the agents for marketing and building highway bridges for the Phoenix Iron Company, an important bridge manufacturing company. The bridge has high technological significance because of its distinctive details representing the era of experimentation in metal truss bridge design and the use of Phoenix sections, which did as much as any detail to prove the value of metal truss bridges during the last half of the 19 th century. The cast- and wrought-iron bridge provides an important snapshot of thinking about bridge design and fabrication prior to steel and standardization. The character-defining features include the truss material, form and method of truss member end connection (pin connected Pratt Pony truss with the eye bar lower chords connected to the verticals by pin plates), the Phoenix section upper chords and inclined end posts, and the floorbeam connection detail (floorbeams framed into the bottom portion of the verticals above the eyebar lower chords). Walp Road Bridge Assessment Page 2

6 Roadway & Site Information Preservation Assessment for Walp Road Bridge Setting Description: The single lane bridge carries a single lane, rural road over a stream, in a rural setting with woodlands, active agriculture, and scattered houses. The bridge is south of a T intersection with Kisenwether Road. The 16'-2" wide bridge roadway is slightly narrower than the 17 ± wide minimum maintained approach roadway. The bridge and road have a very low reported traffic volume (ADT 150). The bridge has been posted for a weight restriction of 4 tons since December 3, 1986, based on the condition of the substructure units. Type of Bridge Service: One lane (less than 18'-wide travelway) serving twodirectional traffic. Bridge Deck Roadway Width: 16'-2" face-to-face bridge rail Approach Travelway Width: 17'± Vertical Clearance: N/A. Functional Classification: Rural Local ADT(Date): The BMS2 lists an ADT of 150vpd (2012). The source of the BMS count on the bridge is not known. This is an estimate and represents the conventional entry for low volume local roads in Luzerne County. Since AASHTO guidance on bridge width is founded on the number and types of vehicles that use a bridge, starting with an accurate assessment is critical, especially when the ADT on a rural local road is less than 400 and is projected to remain under 400 for 20 years. When bridges that do not meet current design criteria (functionally obsolete) are located on very low volume local roads and are performing satisfactorily (absence of documented crash history), AASHTO policy affords the opportunities to keep functionally those bridges in service. Shoulders/Sidewalks: None. Observed Crash History: Nearly all truss verticals exhibit impact damage. Specific crash history data (from local police) was not available for this site, so observed conditions of impact were used to make a determination. Damage appears to be a continual problem at this site. Safety Features: None provided on bridge. Approach guiderail end treatments and transitions do not meet current standards. Proximity of Alternate Routes: To reach the south side of the bridge on Walp Road, there are two alternate routes available. To the west, the detour is 4.4 miles long using Walp Road Bridge Assessment Page 3

7 Preservation Assessment for Walp Road Bridge Kisenwether Road, Mundies Road, SR 0093 and East County Bridge Road to bypass 0.6 miles on Walp Road. To the east, 4.9 miles on Kisenwether Road, Roth Road, St Johns Road, Deep Hole Road and East County Road would be traveled to bypass 0.6 miles on Walp Road. The actual alternate route length traveled would be dependent on the ultimate origin and destination of the individual traveler as the local roadway network is fairly well developed to permit adequate connectivity. Summary Geometric Deficiencies: With a bridge roadway width of 16'-2", the bridge is classified as functionally obsolete because it does not meet the 18' definition of a two lane facility. The closeness of the T intersection with Kisenwether Road to the bridge does require speed reductions for motorists on Walp Road. Further analysis is needed to determine if the geometry of the north approach is intolerable. Performance Summary: The bridge has a history of impact damages to the truss verticals, including several members that have been replaced or straightened. It appears that the bridge is not operating in a safe manner for those vehicles permitted to use this structure. Hydraulics: Nescopeck Creek flows east to west with serious scour at the south abutment and approximately 10 of scour at mid-span. The banks are well vegetated and exhibit moderate erosion with numerous undercut and several leaning trees. The waterway opening is adequate with only a slight chance of overtopping. BMS Condition & Load Sufficiency Condition Code Ratings (2011) Superstructure: 5- Fair Substructure: 2-Critical Deck: 6-Satisfactory Load Ratings Inventory: 4T Operating: 4 T Method: Load factor (floorbeams & stringers) Allowable Stress (truss) & Engineering Judgment (substructure) Posted? Yes. 4 tons based on the condition of the substructure units since December 3, Walp Road Bridge Assessment Page 4

8 Preservation Assessment for Walp Road Bridge LOAD FACTOR METHOD (unless noted otherwise) STRUCTURAL MEMBERS H-20 (20 Tons) HS-20 (36 Tons) ML-80 (37.74 Tons) TK-527 (45 Tons) STRINGERS (inv.) STRINGERS (opr.) FLOORBEAM (inv.) FLOORBEAM (opr.) (2) TRUSSES U2L3 (inv.) (2) TRUSSES U2L3 (opr.) (3) SUBSTRUCTURE (1) Controlling Members (in red) (2) Allowable Stress Method (3) Engineering Judgment Rating The truss Diagonal U2L3 controls the rating of the superstructure with a H20 capacity of 9 tons at inventory stress levels. The substructure controls the overall rating and is the main reason for the weight limit posted on the bridge. The inventory rating level results in a live load which can safely utilize an existing structure for an indefinite period of time. The operating rating level generally describes the maximum permissible live load to which the structure may be subjected. Allowing unlimited numbers of vehicles to use the bridge at operating level may shorten the life of the bridge. For schematics showing the axle loads of typical PennDOT vehicles used for live load ratings, see Appendix. Summary Structural Deficiencies The bridge is rated in overall critical condition due to the condition of the substructure. Based on BMS2 data, confirmed by a cursory field view, the following specific deficiencies were observed. Refer to photographs for additional details. Truss Lines The upper chord and inclined end posts exhibit heavy surface rust with moderate pitting and moderate impacted rust. The north inclined end post of the east truss has minor scale and rust laminations. Each inclined end post of the west truss has small holed through sections in the bottom. Vehicular impact damage is present on the majority of the truss verticals. The truss lower chords, lower lateral bracing and diagonals exhibit heavy surface rust and minor pitting. Walp Road Bridge Assessment Page 5

9 Preservation Assessment for Walp Road Bridge Several diagonals and lower lateral bracing are loose, kinked or bent. Numerous members of the lower chord are loose and several are bowed. The inner bars of L0L2 of the west truss have minor to moderate section loss. The truss pin connections exhibit heavy surface rust and minor to moderate impacted rust. Floorbeams and Stringers The floorbeams and stringers exhibit heavy surface rust with minor scale, rust laminations, and blistering, peeling and flaking paint. Paint Condition Paint loss is present to approximately 60% of the superstructure. Substructure The substructure is in overall critical condition due to undermining at the south abutment. The stone masonry abutments exhibit cracked mortar joints and several cracked stones. There is moderate debris built-up at the truss bearings and there are several stones collapsed on the east bearing of the north abutment. The wingwalls exhibit loose, collapsed, or bulging stones, and missing or deteriorated mortar. Rehabilitation & Preservation Considerations Benchmark for Assessing Rehabilitation The existing bridge has a high historic preservation priority and is located on a very low volume local road with an extremely low reported volume of traffic. There are nearby alternate routes as detailed on Pages 3 and 4 that provide access to the adjacent areas of the bridge. It needs to be determined if a bridge is necessary at this crossing and if making the needed structural repairs to make it adequate could be undertaken. The bridge has structural deficiencies related to deterioration of the truss members, flooring system, the coating system, and the abutments. There are conventional treatments to correct the deficiencies. Specific Options to Address Existing Conditions and AASHTO Criteria The options considered strive to address the well-supported structural deficiencies associated with the physical condition of the bridge, like failing paint and related corrosion of the steel, Phoenix column members with holed sections, and the low load carrying capacity as a result of the undermined abutments. Traditional treatments for improving load carrying capacity based on the capacity of the trusses are considered. This analysis is based on considering options that make the bridge structurally adequate while preserving what makes it historic. Options for addressing the deficiencies are divided into four categories (1) maintenance; (2) rehabilitation without adverse effect; (3) the option of building on a new location without using the old bridge Walp Road Bridge Assessment Page 6

10 Preservation Assessment for Walp Road Bridge and (4) other reasonable options. Maintenance The bridge has deteriorated beyond the point where the structural deficiencies can be addressed by routine maintenance. However, once the bridge is repaired and repainted, there are conventional and cost effective treatments that should be performed on a routine basis in order to significantly reduce life cycle costs, like cleaning the bridge to maximize the life of the coating system. Rehabilitation without Adverse Effect Section 106 of the National Historic Preservation Act of 1966 (NHPA) requires federal agencies to take into account the effects of their proposed improvement on historic properties. An adverse effect on an historic resource occurs when the proposed improvement alters the character defining features that qualify the property for inclusion in the National Register. Adverse effects can be avoided by rehabilitating the structure to the Secretary of Interior s Standards for Rehabilitation. This could be accomplished by implementing the following rehabilitation program. Rehabilitation of the bridge would include conventional treatments that would not alter the characteristics that make the bridge historically significant. Structural deficiencies can be addressed by replacing deteriorated sections or the entire members of the truss and floor system with an in-kind repair or total replacement. A No Adverse Effect is likely as long as the existing end connection details are utilized (pinned truss members and the floorbeam connection detail). Rivets do not need to be utilized for built-up members. Truss strengthening to achieve a higher load capacity can also be accomplished without adverse effects by in-kind replacement with a higher strength material or providing a secondary support system (i.e. post-tensioning or adding supplemental members). The corroded Phoenix sections can be repaired using one of several methods, such as splicing in new pipe sections with welded fins or adding repair plates. This can be evaluated to determine the most appropriate and cost effective way to address the holes in the columns just above each bearing. Truss expansion bearings will be replaced with neoprene or polytetrafluoroethylene (PTFE, better known as Teflon ) bearings while the fixed bearings will be cleaned and repainted. The existing stone abutments can also be rehabilitated without affecting the historic significance and cultural value of the bridge, including repairs to address undermining, cracks, failed mortar joints, bulging stones, missing stones, and deteriorated seats. If it is determined to replace the failing stone abutments with concrete abutments, it will not adversely affect the historic significance and cultural value of the bridge. Appropriate placement of safety features to protect motorists and the truss lines will also not adversely affect the historic significance. The original bridge railings should be retained and the new railings should not be attached to the truss. It may be efficient to lift the truss from its seats in order to repair or reconstruct the abutment(s) in order to allow easier access to the work and avoid costly stream regulations and restrictions. The cost of structural Walp Road Bridge Assessment Page 7

11 Preservation Assessment for Walp Road Bridge repairs to the trusses and cleaning and painting should be estimated with the bridge on the ground rather than over the stream. The following budgetary cost estimate has been developed (utilizing unit costs generated from previous truss rehabilitation projects and modified to reflect specific site constrains/conditions) to provide a rehabilitated structure that makes the bridge adequate for this site and meets a 15 ton minimum capacity. This value is the generally accepted minimum load carrying capacity for rehabilitated structures and represents the anticipated weights for a school bus, oil delivery truck, and small emergency service vehicle. Based on a review of the available structural analysis, it appears that a rehabilitation that results in a 20 ton weight limit would be possible without adverse effect; however, 4 additional truss members would require strengthening. Cost Model - Rehabilitation Program for 15 Ton Capacity Remove Portion of Existing Bridge L.S. $15,000 Temporarily Remove & Reset Truss L.S. $50,000 Construct New Substructure Units 150 $1,500 $225,000 Truss Repairs $7,500 $82,500 Truss Bearings $10,000 $20,000 Clean & Paint Superstructure L.S. $150,000 New Stringers 6 x 75 x 30# = 13,500 LB x $3.50 $47,250 New Timber Deck 1,000 SF x $20 $20,000 Bridge Railing 124 x $100 $12,400 Approach Guiderail 300 x $50 $15,000 Subtotal: $637,150 20% $127,430 TOTAL: $764,580 Considering a 25 year life-cycle analysis that includes a 3% inflation rate and yearly flushing of the truss and bridge seats and spot cleaning and painting, the following costs should be added to this estimate. The cost does not include engineering, mobilization, maintenance and protection of traffic, erosion control measures, etc. Flushing Truss/Bearing Area $1,000/YR 25 ($1,550 ave.) $38,750 Timber Deck Repairs 10 & 20 years $7,875 $3,360 + $4,515 Spot Cleaning & Painting 15 years $15,580 $15,580 TOTAL: $62,205 The cost model yields a total rehabilitation program in present dollars equal to approximately $825,000. The cost for a bridge replacement is estimated to be Walp Road Bridge Assessment Page 8

12 Preservation Assessment for Walp Road Bridge approximately $850,000 based on similar statewide projects. The cost does not include engineering, mobilization, maintenance and protection of traffic, erosion control measures, etc. Other Reasonable Options For Reuse This is a low volume local crossing, and there are adequate bypass routes to access properties on either side of the bridge. Although meeting any likely need, the cost for building a new bridge on a new alignment in close proximity to the existing structure while leaving this historic bridge in place is essentially the same as replacement. Ownership and maintenance of the existing bridge is left undetermined, which might not be conducive to long-term preservation. If it is determined that the actual need does not require a crossing at this location, then removal, relocation, and rehabilitation of the existing structure to the Secretary of Interior s Standards for Rehabilitation is an option that could also result in a No Adverse Effect. Likewise, if it is determined that the actual need requires the construction of a new bridge at the crossing, then the removal, relocation, and rehabilitation of the existing structure to the Secretary of Interior s Standards for Rehabilitation is also an option that could result in a No Adverse Effect. That work would still require that the truss deficiencies be addressed and the bridge cleaned and painted. Due to the length of the span, it is anticipated that this would involve dismantling, rehabilitating, conserving and then relocating the truss for reuse. Summary of Rehabilitation Options Ultimately, the investment into a rehabilitation of a historic bridge works best when there is a long-term potential for preservation. Because of that goal, there is a hierarchy of rehabilitation options. Highest is the rehabilitation of the existing bridge at the current location that continues to meet transportation need at that crossing. Below that is a relocation and rehabilitation of the bridge to another crossing or rehabilitation of the bridge on existing location for a use other than the transportation need. The least preferred option is dismantling and storage of the historic bridge for a future use. This provides no assurance that the bridge will ever be rehabilitated and re-used, and would result in a finding of adverse effect. Based on the observed conditions and usage prior to closure, the Walp Road Bridge could be rehabilitated to carry 15 tons without altering its character defining features and could still be eligible for the National Register. The cost of the rehabilitation would be less than the cost of a new bridge. There are definite challenges to moving forward with rehabilitation due to the work that must be done to address deterioration of the truss members, but rehabilitation appears to be a cost effective option. With conventional treatments for repairing or replacing these elements on the trusses and cleaning and painting the trusses with a properly done coating system, it is likely that the bridge would last a minimum of 25 years with routine maintenance. If the project need is defined as requiring replacement or as not requiring a crossing at Walp Road Bridge Assessment Page 9

13 Preservation Assessment for Walp Road Bridge this location, removal, relocation, and rehabilitation of the bridge would likely result in a No Adverse Effect finding and provide utility of the structure in another use. That use could be in a transportation purpose or in a non-vehicular use. Walp Road Bridge Assessment Page 10

14 4 KISENWETHER ROAD NESCOPECK CREEK 13 FLOW WALP ROAD (T-342) LEGEND PHOTO NUMBER X AND DIRECTION 2 NTS TITLE WALP ROAD

15 BMS # Walp Road over Nescopeck Creek Photo 1 West Elevation Photo 2 South Approach Looking South

16 BMS # Walp Road over Nescopeck Creek Photo 3 South Approach Looking North Photo 4 North Approach Looking South

17 BMS # Walp Road over Nescopeck Creek Photo 5 North Approach T Intersection with Kisenwether Road Photo 6 Deck Looking South

18 BMS # Walp Road over Nescopeck Creek Photo 7 East Truss Line Photo 8 Impact Damaged Vertical East Truss

19 BMS # Walp Road over Nescopeck Creek Photo 9 West Truss with Impact Damaged Diagonal Photo 10 Fixed Bearing East Side South Abutment

20 BMS # Walp Road over Nescopeck Creek Photo 11 Southwest Fixed Bearing with Holes in Pheonix Section Photo 12 General View Underside of Bridge Looking South

21 BMS # Walp Road over Nescopeck Creek Photo 13 South Abutment Photo 14 Northeast Bearing with Pheonix Section with Holed Through Channel

22 BMS # Walp Road over Nescopeck Creek Photo 15 Typical Floorbeam Connection Detail Photo 16 Undermined South Abutment

23 Appendix Truck Loading Information

24 The figures below show common truck axle loadings used for analysis of bridges in the state of Pennsylvania. Note the following: One KIP = 1,000 pounds 2,000 pounds = 1 Ton One wheel load = Axle load divided by two The following sheets show the approximate weights of common vehicles.

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