Preserva on Assessment

Transcription

1 Preserva on Assessment For Sheep Hole Road over Tinicum Creek BMS # Bucks County PennDOT Engineering District 6 0 Final Report Dec 2017 Prepared by TranSystems for the Pennsylvania Department of Transporta on Environmental Policy and Development Sec on

2 BRIDGE LOCATION LOCATION VICINITY N BRIDGE LOCATION MAP Sheep Hole Road (T-420) Over Tinicum Creek Tinicum Township, Bucks County, PA Source: PA Type 10 Map Bucks County

3 RESOURCE LOCATION QUADRANGLE LOCATION SCALE SOURCE 0ft 2000ft USGS 2010 Bedminster, PA N Sheep Hole Road (T-420) Over Tinicum Creek Tinicum Township, Bucks 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 #: 7561 District: 6-0 County: Bucks Township: Tinicum Owner: Bucks County Maintenance: Bucks County Location Information: 1.5 miles east of Ottsville and 0.5 miles south of SR 1014 Bridge Name: Sheep Hole Road (T-420) over Tinicum Creek Bucks County Bridge No. 361 Type: Pony Truss Design: Pratt (Welded) Truss Materials: Steel Date: 1938 Alter/Rehab: 1985 (Reinforced concrete deck, truss cleaning and painting) Source: Style/Inspection File Length: 63' Number Spans: 1 Deck Width: (out-to-out dimension) Bridge Description The single span 63 -long, skewed (60º) welded Pratt pony truss bridge is supported on stone masonry abutments. The inclined end posts, upper chords, verticals and diagonals are rolled steel sections and the bottom chords are pairs of angles with battens. There are 4 rolled steel floorbeams and 6 rolled steel stringers. The Sheep Hole Road Bridge Assessment Page 1

5 floorbeams extend beyond the truss lines to support rolled steel outriggers. A reinforced concrete deck with integral wearing surface is supported by the stringers. The bridge railing on each side is comprised of a steel channel and an I-beam welded to the truss members. NR Eligibility Status: Eligible as a contributing element to the Ridge Valley Rural Historic District and under Criterion C for technological significance. Historic Preservation Priority: Moderate (see Protocols for Levels of Priority located at Historic Preservation Priority Justification: The Ridge Valley Rural Historic District, located in Tinicum Township, Bucks County is locally significant under Criterion A in the area of Agriculture as an example of farming in small stream valleys in the county. This type of farm forms a distinctive subset of traditional Bucks County agricultural development. It is also eligible under Criterion C for its architecture which is representative of southeast Pennsylvania rural vernacular architecture from the late 18th to the early 20th century. Throughout the Ridge Valley Historic District winding dirt roads, stone farmsteads and outbuildings, fields and meadows are found in visual harmony with the intact and undisturbed wetlands and woodlands. These features provide an outstanding context for the district s architecture. The period of significant is circa 1790 to circa The steel truss bridge was built by the WPA in It is one of the earliest all welded bridges, an uncommon bridge type, in the state. The character defining features of the bridge include the truss form and method of truss member end connection (welded Pratt pony truss) and the floorbeam connection detail (floorbeams welded to lower chord gusset plates). Roadway & Site Information Setting Description: The bridge on T- 420 (Sheep Hole Road) is north of a T intersection with Headquarters Road (SR 1012). The bridge carries one lane of a township road over a stream in a sparsely developed, forested setting in the National Register-listed Ridge Valley Rural Historic District. The wide bridge roadway is wider than the approximately 14 wide minimum maintained travelway. The bridge and road has a very low reported traffic volume. Type of Bridge Service: One lane (less than 18'-wide travelway) serving two-directional traffic. Note that the approach roadways are only approximately 14 wide. Bridge Roadway Width: 17'-11" face-to-face of railing Approach Travelway Width: 14'-0 ± Vertical Clearance: N/A Sheep Hole Road Bridge Assessment Page 2

6 Functional Classification: Rural Local ADT(Date): BMS2 lists an ADT of 50 vpd (2016). This is a very low volume local road with an extremely low ADT that is likely well below 50 based on observations made during the field view. The source of the BMS traffic count on the bridge is not known. 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: Minor impact damage is present to the I-beam rail element near the south end of the east truss. 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 from an isolated incident, and is not indicative of a continual problem. Safety Features: The bridge railing is comprised of a channel and an I-beam welded to truss members along the inner face of each truss. There is no proper transition between bridge railing and approach railing. The safety features do not meet current standards. Proximity of Alternate Routes: To reach the south side of the bridge on Sheep Hole Road, there are two alternate routes available. To the west, the alternate route is 2.9 miles long, using Geigel Hill Road, SR 1014, Durham Road and SR 1012 to bypass 1.0 miles on Sheep Hole Road. To the east, the alternate route is 1.9 miles, using Geigel Hill Road, Tankhannen Road, Ridge Valley Road, and SR 1012 would be traveled to bypass 1.0 miles on Sheep Hole Road. The actual alternate route length traveled would be dependent on the ultimate origin and destination of the individual traveler. Neither route has an height or weight restrictions, however, there are a number of one lane bridges on both routes. Summary Geometric Deficiencies: With a bridge deck width of 17'-11, the bridge is classified as functionally obsolete because it does not meet the 18' definition of a two lane facility. The road is also a one lane facility. The sight distances appear to be sufficient. Performance Summary: While the bridge does not meet current design requirements, there is minimal evidence of a vehicular crash history and therefore it appears that the bridge is operating in a safe manner for those vehicles permitted to use the bridge. Sheep Hole Road Bridge Assessment Page 3

7 Hydraulics: Tinicum Creek flows straight north to south with up to 33 of scour along the full length of the north abutment. The channel impacts the bank behind the wingwall in the northwest quadrant. Erosion with exposed tree roots is present along the banks, the most severe instance of erosion occurring along the east bank resulting in migration of channel toward the east bank. Flood debris is present on several floorbeam to flanges. There is an occasional risk of overtopping as per BMS2. BMS Condition & Load Sufficiency Condition Code Ratings (2016) Superstructure: 5 Fair Substructure: 4 Poor Deck: 5 Fair Controlling Load Ratings Inventory: 21 T Operating: 35 T Method: Load factor (floorbeams & stringers) Allowable Stress (truss) Posted? No. LOAD FACTOR METHOD (unless noted otherwise) STRUCTURAL MEMBERS H20 (20 Tons) HS20 (36 Tons) ML80 (37.74 Tons) TK527 (45 Tons) INT. STRINGERS (inv.) INT. STRINGERS (opr.) (1) FLOORBEAM (inv.) * 25* (1) FLOORBEAM (opr.) (2) TRUSSES U3L4 (inv.) (2) TRUSSES U3L4 (opr.) (1) Controlling Members (in red) (2) Allowable Stress Method (*) denotes insufficient capacity for indicated truck The latest analysis is from The floorbeams control the ratings. The controlling truss members are U3L4 with a posting of 40 tons at inventory stress levels and 52 tons at operating stress levels. For truck loading schematics showing the axle loads, see Appendix. 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. Sheep Hole Road Bridge Assessment Page 4

8 Summary Structural Deficiencies The bridge is rated in overall poor (4) 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 connection angle weld to vertical gusset plate is cracked (8 ) at the outrigger connection to Floorbeam 3 at the upstream end. Minor scrapes are present to the members of the east truss and minor impact damage is present to a vertical member near south end of east truss. There is debris accumulating between the lower chord gusset plates. There are cracked welds that have been repaired on the bridge. Floorbeams and Stringers The rolled floorbeams are in overall good condition with some paint chipping and pitting as well as some debris lodged in the floorbeams. The six rolled stringers have some areas of surface corrosion throughout. The underside of thetop floagnes of the strings over the floorbeams exhibit moderate corroded and delaminated areas with minor section loss. Bearings The bearings exhibit area of minor corrosion and impacted rust. The south abutment bearing plates for Stringers 2, 4 and 5 are shifted (2¾ maximum) from under the bearing. Substructure The stone masonry abutment stems exhibit minor to moderate joint cracking and mortar loss along the waterline. The wingwall in the northwest quadrant has severe mortar loss along the waterline. The south abutment concrete bridge seat has several horizontal and vertical cracks up to ⅛ wide. The south abutment backwall concrete exhibits hairline cracks over the entire length. There are minor edge spalls along the top of the north abutment backwall. The north abutment footing is exposed up to 33 deep at the interface of abutment and wingwall in the northwest quadrant. The bridge seats have minor debris accumulation. Deck The underside of the reinforced concrete deck has several transverse hairline cracks, mostly near the north abutment. There are typical shallow edge spalls at interface with the stringers. The deck underside has spalls up to 3 long x 4 wide x 1 deep with exposed corroded reinforcing steel. The steel sliding plate of deck expansion joint is loose. Sheep Hole Road Bridge Assessment Page 5

9 Rehabilitation & Preservation Considerations Benchmark for Assessing Rehabilitation The existing bridge has a moderate historic preservation priority and is located on a very low volume local road with an extremely low reported volume of traffic. There are 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 satisfactory could be undertaken. The bridge has structural deficiencies related to deterioration of the concrete substructure and deck. 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 cracked concrete on the deck and substructure. There are traditional treatments for improving load carrying capacity based on the capacity of the trusses themselves, and they are considered. This analysis is based on considering options that make the bridge structurally satisfactory 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. Maintenance The substructure of the bridge has deteriorated beyond the point where the deficiencies can be addressed by routine maintenance. However, if the bridge were to be repaired, there are conventional and cost effective treatments that could be performed on a routine basis in order to significantly reduce life cycle costs, like removing vegetation growth from the masonry and cleaning the bridge to maximize the life of the coating system in addition to periodic repainting. 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. The cracked weld is not located on a primary load carrying member and could be repaired by welding or adding bolted repair plates. The stringer expansion bearings would be reset. The existing abutments could also be repaired/partially reconstructed without affecting the historic Sheep Hole Road Bridge Assessment Page 6

10 significance and cultural value of the bridge. The substructure units could also be rehabilitated and this would not adversely affect the historic significance and cultural value of the bridge as they are not considered a character defining feature of the bridge. Appropriate placement of safety features to protect motorists and the truss lines would also not adversely affect the historic significance. The original bridge railings could be retained and the 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 satisfactory for this site and maintains the existing structural capacity which is good for current legal loads. This value is above the generally accepted minimum load carrying capacity of 15 tons for rehabilitated structures and represents the anticipated weights for a school bus, oil delivery truck, and small emergency service vehicle. Cost Model - Rehabilitation Program for Current Legal Loads Spot Clean & Paint Superstructure L.S. $100,000 Remove and Reset Masonry 100SF x $100/SF $10,000 Repoint Masonry 500SF x $25/SF $12,500 Truss Repair 1@ $7,500 $7,500 Reset Stringer Bearings 3@ $1,000 $3,000 New Deck Expansion Joint $200/LF $4,000 Approach Guiderail 300 x $50 $15,000 Subtotal: $152,000 20% $30,400 TOTAL: $182,400 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 $38,950 TOTAL: $77,700 The cost model yields a total rehabilitation program in present dollars equal to $260,000. The cost for a bridge replacement is estimated to be approximately $820,000 based on similar statewide projects. The cost does not include engineering, mobilization, maintenance and protection of traffic, erosion control measures, etc. Sheep Hole Road Bridge Assessment Page 7

11 Other Reasonable Options For Reuse This is a very low volume local crossing, and there are 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 to the Secretary of Interior s Standards for Rehabilitation is an option that could also result in a No Adverse Effect. Likewise, if construction of a new bridge is required based on the project needs, 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. 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, the Sheep Hole Road Bridge could be rehabilitated to continue to carry full legal loads 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 substructure, but rehabilitation appears to be a cost effective option. With conventional treatments for repairing or replacing these elements on the abutments 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 or if the actual need does not require a crossing at 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. Sheep Hole Road Bridge Assessment Page 8

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13 FLOW SHEEP HOLE ROAD T-420 TINICUM CREEK 11 1 LEGEND PHOTO NUMBER X AND DIRECTION NTS TITLE SHEEP HOLE ROAD

14 Photo 1 South Elevartion Photo 2 Oblique North Elevation Sheep Hole Road Bridge Assessment Photo Page 1

15 Photo 3 View of The Bridge from West Approach Looking East Photo 4 West Approach Looking West Sheep Hole Road Bridge Assessment Photo Page 2

16 Photo 5 Bridge Deck Looking East Photo 6 North Truss Sheep Hole Road Bridge Assessment Photo Page 3

17 Photo 7 Typical Truss Bridge Seat Photo 8 Typical Debris Accumulation at Lower Chord Joints Sheep Hole Road Bridge Assessment Photo Page 4

18 Photo 9 Bridge Railing Attachment (Note Minor Collision Damage) Photo 10 Debris Accumulatin at Truss Bearing Sheep Hole Road Bridge Assessment Photo Page 5

19 Photo 11 View of South Truss. Note Outrigger and Floorbeam Connection Photo 12 Wingwall in the Southwest Quadrant Sheep Hole Road Bridge Assessment Photo Page 6

20 Photo 13 Spalls along Edge of Concrete Deck and Outrigger Detail Photo 14 East Abutment. Note Water Seepage through Deck Joint Sheep Hole Road Bridge Assessment Photo Page 7

21 Photo 15 West Abutment, Note Flood Debris Sheep Hole Road Bridge Assessment Photo Page 8

22 Appendix Truck Loading Information

23 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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