Preserva on Assessment

Transcription

1 Preserva on Assessment For Seidersville Road Bridge over Saucon Creek BMS # Northampton County PennDOT Engineering District 5 0 Final Report June 2016 Prepared by TranSystems for the Pennsylvania Department of Transporta on Environmental Policy and Development Sec on

2 BRIDGE LOCATION N BRIDGE LOCATION MAP Seidersville Road over Saucon Creek City of Bethlehem, PA Source: PA Type 10 Map Northampton County

3 RESOURCE LOCATION QUADRANGLE LOCATION SCALE SOURCE N 0ft 2000ft USGS 1999 Hellertown, PA Seidersville Road over Saucon Creek City of Bethlehem, Northampton County, PA

4 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 Historic Bridge Rehabilitation 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: 5-0 County: Northampton Township: Bethlehem Owner: Northampton County Maintenance: Northampton County Location Information: 0.2 miles west of SR412 and 1.2 miles northwest of Hellertown Bridge Name: Seidersville Road over Saucon Creek Type: Thru Truss Design: Pratt (Welded) Truss Materials: Steel Date: 1936 Alter/Rehab: 1966 Source: Inspection File Length: 135' Number Spans: 1 Deck Width: 20-6 (out-to-out dimension) Bridge Description The single span, 135 -long, 9 panel, welded Pratt thru truss bridge is supported on stone abutments with concrete bridge seats. The members are composed of rolled I and H sections. The bottoms chords are a pair of toe out channels with battens. The portal bracing, struts and top lateral bracing are also rolled sections. The rolled steel floorbeams and stringers support a reinforced concrete deck. A steel channel top rail and concrete filled beam bottom rail form the bridge railing and are attached to the inner faces of the trusses. Seidersville Road Bridge Assessment Page 1

5 NR Eligibility Status: Eligible under Criterion C for technological significance. Historic Preservation Priority: High (see Protocols for Levels of Priority located at insert hyperlink to Appendix 2 in the Management Plan Document). Historic Preservation Priority Justification: The bridge appears to be complete. The bridge ranks as one of the early, all-welded bridges in the state, and it is technologically significant representing the transition from riveted to welded connections in bridge fabrication. The bridge is one of about a dozen identified welded off-system truss bridges built in Pennsylvania. Most predate World War II, and it is the only identified welded thru truss bridge in the state. The bridge stands remarkably unchanged, which augments its technological and historical significance. The character-defining features are the truss form and method of truss member end connection (welded, Pratt thru truss) and its completeness. Roadway & Site Information Setting Description: The bridge carried a 2 lane road over a stream in a forested setting with modern houses. The area on the east side of the bridge is predominately a large residential area in the town of Hellertown while west of the bridge is forested with scattered residences. Seidersville Road terminates at a T intersection with Creek Road approximately 0.1 miles west of the bridge. The athletic campus of Lehigh University is located in the west side of Creek Road. The Pennsylvania Fish and Boat Commission has posted signs at the bridge indicating that Saucon Creek is a part of the Trophy Trout Program and that special fishing regulations apply. The bridge has been closed since July 23, Type of Bridge Service: Two lanes (one lane in each direction) serving two-directional traffic. Bridge Roadway Width: 18'-3 curb-to-curb Approach Travelway Width: Varies 18' ± Vertical Clearance: 16-0 Functional Classification: Rural Local ADT(Date): Present ADT = 0 as the bridge is currently closed to traffic. The 2016 BMS2 listed an ADT of 600 vehicle per day. The source of the BMS traffic count on the bridge is not known. This bridge has been closed to all traffic since July 23, Shoulders/Sidewalks: None. Seidersville Road Bridge Assessment Page 2

6 Observed Crash History: There is no evidence of a crash history on the bridge. Specific crash history data (from local police) was not available for this site, so observed conditions of impact were used to make a determination. Safety Features: The bridge railing consists of a steel channel and concrete filled tube section welded to the inner face of each truss line. Masonry parapet walls make up the flared approach railing at each approach. There is no proper transition between bridge railing and approach parapet. The safety features do not meet current standards. Proximity of Alternate Routes: To reach the east side of the bridge on Seidersville Road, there are two alternate routes available. To the north, the alternate is 1.1 miles long using Creek Road, College Drive, Silvex Road and Ravena Street to bypass 0.3 miles on Seidersville Road. To the south, the alternate route is 2.1 miles long using Creek Road, West Water Street, Main Street, Bachman Street, Whitaker Street and West High Street would be traveled to bypass 0.3 miles on Seidersville Road. Neither route has weight restrictions. The north route has a height restriction on Silvex Road of The actual alternate 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: Although the bridge deck roadway width meets the minimum criteria to be classified as a 2-lane facility, it does not meet minimum design standards for a 2-lane roadway and is classified as functionally obsolete. Performance Summary: When the bridge was open to traffic (restricted to a load of 15 tons), while it did not meet current design requirements, there was no evidence of a crash history and therefore it appears that the bridge was operating in a safe manner for those vehicles permitted to use the bridge at that time. Hydraulics: Saucon Creek flows straight west to east with some indication of scour. There is 6 of scour near the north abutment with undermining under the bottom of the stem which is directly founded on bedrock. The waterway opening appears adequate. There is an occasional chance of topping as per BMS 2. BMS Condition & Load Sufficiency Condition Code Ratings (2016) Superstructure: 1 Imminent Failure Deck: 4 - Poor Substructure: 5 Fair Controlling Load Ratings Inventory: 0 T Operating: 0 T Method: Load factor (floorbeams & stringers) Allowable Stress (truss) Posted? Yes. The bridge is currently closed to all traffic. Prior to its closure, the bridge was posted for 15 tons since June 1, Seidersville Road Bridge Assessment Page 3

7 RATING SUMMARY (TONS) (*) Inventory Rating (IR) Operating Rating (OR) Tons Tons H20 (20 Tons) HS20 (36 Tons) TK527 (40 Tons) ML80 (37.74 Tons) (*) Insufficient capacity shown in red The above analysis is from prior to the bridge closure in The floorbeams controlled the ratings. The trusses have sufficient capacity for current legal loads. An updated load rating will be required as part of any project associated with this structure to determine current load carrying capacity. 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 imminent failure condition (1) due to the condition of the superstructure. The 2016 inspection reflects an inspection limited to critical areas only and with respect to pedestrian traffic only. In all cases, no hazards to pedestrians was observed. Since its closure in 2007, the bridge has been receiving inspections limited to critical areas only. 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 truss and bracing members exhibit peeling paint, rust and pitting throughout with minor section losses to the truss bottom chords and inclined end posts near the truss bearings. There are several small holes to the bottom chord near the gusset plate at the southwest truss bearing and one area of 100% section loss along lower chord. Bearings The fixed bearings at the west abutment exhibit severe rust and the roller expansion bearings at the east abutment are frozen. Seidersville Road Bridge Assessment Page 4

8 Floorbeams The outer portions of the floorbeams have up to 70% section loss to the flanges. Impacted rust has lifted the east end of the top cover plate of Floorbeam 8 breaking several tack welds. Stringers The stringers near the abutments have large gaping web holes varying from 2 to full height of the web extending up to 2 from the front face of bridge seat and severe losses in both flanges extend farther beyond the front face of the bridge seat. In addition, the fascia stringers exhibit severe rust throughout with moderate to severe section losses to the full length of the bottom flange and to the top flange at the floorbeams. Bracing The bracing members exhibit pitting, peeling paint, and rust. There is heavier rust on the bottom lateral braces at the ends. Deck The bridge deck is in poor condition exhibiting severe spalls, cracks, scaling and popouts. A 5 x 1 hole exists at the northeast corner. Substructure The concrete bridge seats exhibit cracks and minor spalls, and the stone masonry abutment stems and wingwalls have hairline mortar cracking. Rehabilitation & Preservation Considerations Benchmark for Assessing Rehabilitation The existing bridge has a high historic preservation priority and is located on a low volume local road with a low reported volume of traffic. There are nearby alternate routes as detailed on Page 3 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 trusses, floor system, deck and the coating system. There are conventional treatments to correct the deficiencies. Specific Options to Address Existing Conditions and AASHTO Criteria The options considered strive to address the documented structural deficiencies associated with the physical condition of the bridge, such as failing paint and related corrosion of the floor system. 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 and (4) other reasonable options. Seidersville Road Bridge Assessment Page 5

9 Maintenance The bridge has deteriorated beyond the point where the structural deficiencies can be addressed by routine maintenance. However, if the bridge were to be 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 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 (floorbeam connection detail). Truss repair can also be achieved without adverse effects by providing repair plates over deteriorated sections of the original truss members. 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. Replacement of the reinforced concrete deck is permissible. Repair to the substructure units will not adversely affect the historic significance and cultural value of the bridge if properly performed. Appropriate placement of safety features to protect motorists and the truss lines is also permissible. The original bridge railings should be retained and the new railings should not be attached to the trusses. 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 the trusses are capable of supporting full legal loads and that the floor system upgrade resulting in a 20 ton weight limit would also be possible without adverse effect. If additional carrying capacity is determined to be required when a purpose and need is developed for the project, additional analysis would be needed. This would be addressed by means of additional analysis during the NEPA process Seidersville Road Bridge Assessment Page 6

10 Cost Model - Rehabilitation Program for 15 Ton Capacity Remove Portion of Existing Bridge L.S. $15,000 Temporary Structure Support L.S. $75,000 Truss Repairs $7,500 $15,000 Truss Bearings $10,000 $20,000 Clean & Paint Superstructure L.S. $300,000 New Deck R.C. Slab [135 x 20.5 x 8/12]/27 x $1250/CY $85,500 New Stringers 2 x 6 x 20 x 30#/ = 360 LB x $5.00 $1,800 Floorbeam Repairs $12,500 $100,000 Bridge Railing 270 x $100 $27,000 Approach Guiderail 300 x $50 $15,000 Subtotal: $654,300 20% $130,860 TOTAL: $785,160 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 Spot Cleaning & Painting 15 years $77,950 TOTAL: $116,650 The cost model yields a total rehabilitation program in present dollars equal to $910,000. The cost for a bridge replacement is estimated to be approximately $2,000,000 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 alternate 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 is an option, however, it would most likely result in an Adverse Effect. Likewise, if construction of a new bridge is required at the crossing based on project needs, then the removal, relocation, and rehabilitation of the existing structure is also an option but would most likely result in an Adverse Effect. Due to the length of the span, it is anticipated that relocation would involve dismantling, rehabilitating, conserving and then relocating the truss for reuse. Seidersville Road Bridge Assessment Page 7

11 However, it must be pointed out that the welded connections (a character defining feature) make dismantling the truss for reuse a challenging option. Welding causes changes to the steel at the microscopic level. Breaking the existing welds to permit dismantling and then subsequently grinding the welds and rewelding the truss together for re-installation, while technically feasible is most likely not a practical option. This option would potentially introduce stress risers in the structural elements due to the grinding and rewelding, which could result in the initiation of fatigue cracking. From an engineering perspective due to the fracture critical nature of trusses, dismantling and relocation of the welded trusses would not be considered. 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 rehabilitation of the bridge on existing location for a use other than the transportation need. Based on the observed conditions and usage prior to closure, the Seidersville 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 floor system, deck, and truss members, but rehabilitation appears to be a cost effective option. With conventional treatments for repairing or replacing these elements on the floor system 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 construction of a new bridge is required at the crossing based on project needs, then an Adverse Effect finding is anticipated since bridge relocation is most likely not a feasible option. Seidersville Road Bridge Assessment Page 8

12 SEIDERSVILLE ROAD ' 13 WEST '-3" FLOW SAUCON CREEK EAST 18'-8" LEGEND X PHOTO NUMBER AND DIRECTION UTILITY POLE TITLE NTS SEIDERSVILLE ROAD

13 Photo 1 Oblique North Elevation Looking West Photo 2 East Approach Looking East

14 Photo 3 View North at Driveway in Northeast Quadrant Photo 4 East Approach Looking West toward Bridge

15 Photo 5 West Approach Looking West Photo 6 West Approach Looking East toward Bridge

16 Photo 7 Bridge Deck Looking West Photo 8 Truss Form Looking West. Note Portal and Structural Detail

17 Photo 9 Typical Railing Termination Photo 10 Fenced Off Area of Severe Deck Deterioration at Northeast Corner

18 Photo 11 Deck Edge Deterioration Photo 12 Posted Notice Concerning Trophy Trout Program

19 Photo 13 Southwest Wingwall Photo 14 General View of Underside Looking West

20 Photo 15 Floorbeam Connection Detail Photo 16 Typical Truss Lower Chord Detail

21 Photo 17 Deck Construction Joints Photo 18 Expansion Bearing at West Abutment

22 Photo 19 Severe Stringer Deterioration at West Abutment Photo 20 Severe Stringer Deterioration at West 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.

25

26