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The original plans for the Duboistown Bridge are labeled "Alternate Riveted Truss Design." This unusual labeling suggests that the truss bridge seen today was not what had been originally proposed for the crossing. Indeed, some research shows that the original design was intended to be an open-spandrel concrete deck arch bridge. The magazine Municipal Engineering included a notice that bids would be received until September 4, 1917 for a 1500 foot open spandrel arch bridge, to consist of 13 spans with 98 foot clear spans. At some point however, these plans must have been scrapped and the alternative truss design developed, although the reason for this is unknown. Cost may have been an influence. At the time, concrete bridges may have been more expensive, since they represented a newer technology, and metal truss bridges during this time, the tried and true technology, may have been less expensive.
The Duboistown Bridge is a very significant historic bridge, and also an extremely beautiful bridge, even if PennDOT and the PHMC fail to acknowledge any of this. The bridge has three primary areas of historic significance: size, historic integrity, and truss configuration.
First, the bridge is noteworthy for its size. The Duboistown Bridge is today a rare and noteworthy example of a long truss bridge, with the bridge consisting of seven spans totaling over 1000 feet in length. The Susquehanna River was once home to many multi-span truss bridges, however one by one these bridges have been demolished such that those which survive are extremely rare. Despite the size and length of the the entire West Branch of the Susquehanna River, the Duboistown Bridge is the only highway truss bridge that has more than two spans! A similar pattern of demolition and increased rarity of long multi-span truss bridges is observed throughout Pennsylvania. Bridgemapper suggests that there are fewer than 10 remaining truss bridges in all of Pennsylvania that have five or more spans.
Second, the Duboistown Bridge is noteworthy for its historic integrity. Rivers large enough to demand bridges of this length have fewer bridges on them because of the cost of constructing large bridges. As such, each bridge on a large river tends to have a lot of traffic, and as a result surviving historic bridges that cross large rivers normally have received a lot of repairs and alterations over their lives that have damaged the historic integrity of the bridge. Despite this however, the Duboistown Bridge retains a remarkable level of historic integrity. From the overall superstructure, to the many architectural details on the bridge, the Duboistown Bridge has a very high degree of historic integrity.
The bridge includes original lattice railings which are completely unaltered. The bridge has only one sidewalk, which is cantilevered on the western side of the bridge. The railings on the bridge are configured in a traditional manner for bridges with a single cantilevered sidewalk. The sidewalk has a lattice railing installed on the outside edge of the sidewalk. The east side of the bridge has an identical railing mounted inside the truss line. There are no railings present alongside the western truss line. This clearly demonstrates how during the period when this bridge was built, the purpose of railings was only to prevent someone from falling or driving into the river. The function of guiding the direction of travel for car or to protect the truss superstructure was not a concern during this time in history. In the case of the Duboistown Bridge, the railings are identical and are approximately 30 inches in height. There are attractive concrete posts with inset rectangles included in the design of the pedestrian railing, which also support cast light standards.
The bridge's truss superstructure is largely unaltered. HistoricBridges.org found no evidence of any major replacement of rivets with bolts nor were any noteworthy welded alterations or additions found. The only noteworthy alteration was the addition of a support system for some pipe on the east side of the truss. Original built-up floorbeams remain on the bridge.
This bridge also has some of the most handsomely decorated abutment railing detail ever seen in a bridge. Concrete railings on the abutments provide an attractive approach to the bridge, with the concrete providing a pleasing contrast to the metal of the bridge superstructure. Aside from the visual qualities of this contrast, the concrete abutment railings clearly define the differing role and materials of the substructure versus the superstructure, and as such the design conveys the structure of the bridge to observers in an honest manner. The concrete railings are a relatively massive design, with pieced openings giving it an abstract balustrade design. The railings terminate at large bulkheads which on the southeast and northwest corners include large bronze plaques. The bulkheads at the ends in front of the truss are capped with a design that is reminiscent of the stylistic keystone shape that is used as a symbol for Pennsylvania. The other ends of the abutment railings are capped with decorative cast metal standards that likely originally held lighting for the bridge. The truss bridge itself also retains a number of these standards on the concrete posts that are present along the pedestrian sidewalk railing system.
Both the abutments and the piers of the bridge are concrete, and they feature a simple pattern of parallel horizontal lines on them.
The bridge also has the unusual feature of latticed built-up beams mounted on top of the truss that support electrical wires.
Truss Configuration.
Finally, the Duboistown Bridge is noteworthy for its truss configuration. With a top chord / end post design featuring exactly five slopes, this bridge is a camelback truss. Most surviving post-1920 bridges built in Pennsylvania are state standard Pratt or Parker truss bridges, so this camelback example is very unusual. There are no other camelback truss bridges on the Susquehanna River, and the number of camelback truss bridges of any age in Pennsylvania anywhere is extremely small.
The Pennsylvania Historic Bridge Inventory found this bridge ineligible for listing in the National Register of Historic Places. Perhaps in 1996 (14 years ago in 2010) when the Historic Bridge Inventory currently in use was created, bridges such as the Duboistown Bridge were a dime a dozen in Pennsylvania. However, today, the Duboistown Bridge is an very significant historic bridge. Calling the Duboistown Bridge ineligible for the National Register of Historic Bridges in Pennsylvania in 2010 is nothing short of obscene. It is offensive to the heritage of the bridge and has the effect of making it look like somebody simply wanted to avoid having to conduct Section 106 for this bridge.
How did this problematic assessment occur? For each state, a Historic Bridge Context which is developed as part of the historic bridge inventory process defines the system for determining whether or not a bridge in the state is historic. Pennsylvania appears to still be using the same context in 2010 that was in use in 1996. This context appears to find a large number of metal truss bridges in Pennsylvania at that time, and as such the context recommends that only those truss bridges with "innovative or distinctive details" should be considered eligible. Unlike the inventories for other states such as Michigan, there does not appear to be a sufficient provision in the Pennsylvania context for defining a bridge that might lack "innovative or distinctive details" as historic on the basis of exceptional historic integrity or exceptional structure length, both representing a significant engineering achievement under Criterion C of the National Register of Historic Places. Similarly, there also is no apparent attention given to defining a bridge as historic in Pennsylvania as "representative examples" of a period in history. There also is not sufficient attention given to defining a bridge as historic based on advancements in state standard plans for different bridge types.
HistoricBridges.org recommends that the historic bridge context for Pennsylvania be revised and expanded to cover the aforementioned shortcomings, and the inventory updated accordingly. Further, a revised context should also take greater consideration into the drastic reduction of metal truss bridges in Pennsylvania. Those standard plan metal truss bridges in Pennsylvania once described as "common technology" are no longer such, both due to attrition and also due to the fact that technologies such as riveting and the use of built-up beams with v-lacing and lattice have been considered obsolete bridge construction methods for nearly 50 years. They are today "historic technologies."
Whether or not PennDOT and PHMC choose to acknowledge it or not, it is clear that the Duboistown Bridge is indeed a historic bridge with a large amount of significance.
PennDOT has decided to demolish and replace this historic bridge with a mundane slab of concrete. The usual excuses for demolition are given, including narrow deck width and structural deficiency, although the bridge actually is not in that bad of a condition and could easily be rehabilitated. It is likely that PennDOT also gave its usual unproven claim that a replacement bridge will last 100 years. Whether on purpose or not, PennDOT also tends to say things that make the average citizen get the incorrect idea that a replacement bridge will last 100 years with no maintenance costs, while a rehabilitated bridge would cost a ton of money to maintain over future year. Neither of these ideas are correct, truth is somewhere in the middle of these ideas.
While the replacement bridge might not be structurally deficient, it most certainly will be "visually deficient." The structure that will replace this bridge will be a structure so plain, ugly, and unremarkable in design that calling it a "bridge" is insulting to the engineers and craftsman who designed, fabricated and erected the beautiful historic Duboistown Bridge.
Despite the ugliness of modern bridges, sometimes they can have their uses in historic bridge preservation, and indeed here at Duboistown would have been one good example. An excellent preservation solution here would have been to build a new one-lane bridge next to the historic bridge to form a one-way couplet of bridges. Alternatively, another excellent solution would have been to simply leave the historic bridge standing next to its replacement. Indeed, even with the current replacement plan this solution is possible and that fact that it is not being done is absolutely absurd. As current plans stand, the replacement bridge will indeed be built on a new alignment next to the historic bridge. The problem is that these same plans also call for the demolition of the historic bridge following completion of the replacement bridge. This is ridiculous, but it happens all the time in Pennsylvania. HistoricBridges.org sincerely hopes PennDOT will have a change of heart and choose to leave this bridge standing next to its replacement, either as an abandoned historic ruin or in use for non-motorized traffic. Up until the moment the bridge is demolished, it is not too late to choose to save this bridge. However, once it is demolished, it can never be brought back again.
Anyone familiar with the content on HistoricBridges.org likely tires of reading the same type of narrative over and over again on the website. However, Pennsylvania constantly demolishes historic bridges even when the historic bridge is not in the way of the replacement bridge, and HistoricBridges.org is committed to bringing attention to this whenever this type of demolition occurs and to also point out the absurdity of it.
Even if there is no money to restore these bridges when they are left standing next to their replacement, it does not appear that PennDOT or many Pennsylvania citizens realize how long these bridges can stand with no work done on them whatsoever, once they no longer carry vehicular traffic.
Information and Findings From Pennsylvania's Historic Bridge InventoryDiscussion of Bridge The 1,407'-long, 7-span, riveted camelback thru truss bridge built by the county in 1922-23 is supported on concrete abutments and piers. Each span is about 199' long. The trusses are traditionally composed with built up members. There are no innovative or distinctive details. The cantilevered sidewalk on the downstream side is finished with a lattice railing that matches that used on the inside of the truss lines. The 1922-23 camelback thru truss bridge is typical of the period, and it is not historically or technologically significant. It was designed with standard details for high capacity usage. All of the members reflect the standardization that was common in rivet connected truss bridges by 1910. Discussion of Surrounding Area The bridge carries a 2 lane road over the river between Williamsport and Duboistown. There is a passive recreation park and water/sewage treatment plant on the Williamsport side, and the Duboistown side is dominated by highly altered vernacular buildings and modern buildings. Neither side has historic district potential. Bridge Considered Historic By Survey: No |
This historic bridge has been demolished. This map is shown for reference purposes only.
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