I recently received a news release from Route 66 The Road Ahead Partnership about how a historic preservation specialist on behalf of the organization weighed in on several proposals for the William H. Murray Bridge, aka Pony Bridge, near Bridgeport, Oklahoma.
That led me to ask: What exactly are the proposals for the Pony Bridge?
In case you’re not familiar with it, the Pony Bridge remains one of Route 66’s most iconic spans. Built in 1934, it stretches more than 3,900 feet over the South Canadian River and consists of 38 yellow “pony” trusses, hence its nickname. The bridge appears in the 1939 Oscar-winning film “The Grapes of Wrath.” In 2016, the bridge appeared on Preservation Oklahoma’s Most Endangered Historic Places list.
Not only does the bridge carry Route 66, but also U.S. 281, making it a vital transportation link in that part of the state.
The bridge also is too narrow for modern standards and load-rated at only nine tons, despite the fact big trucks sometimes use it as a short cut to Interstate 40.
The Oklahoma Department of Transportation emailed a helpful link about the proposed options for the Pony Bridge. In short, the bridge is eligible for a federal Better Utilizing Investments to Leverage Development (BUILD) grant that “provides a unique opportunity for the DOT to invest in road, rail, transit and port projects that promise to achieve national objectives … to fund projects that have a significant local or regional impact.”
The state’s transportation agency stated:
ODOT feels strongly that this project is an ideal candidate for this competitive grant. The bridge is an iconic structure on Historic Route 66 and has achieved national and international recognition as such. Recent interest in revitalizing Route 66, including the forthcoming 100-year anniversary of the historic road in 2026, has brought additional attention to Oklahoma’s transportation resources related to Route 66. ODOT is seeking financial assistance through the BUILD grant in order to address the deficiencies in the William H. Murray bridge and provide a sound crossing over the Canadian for the 2026 anniversary. […]
Regardless of the alternative that ODOT selects for the BUILD application, ODOT and FHWA will continue consultation under the referenced regulations to seek ways to avoid, minimize, or mitigate adverse effects to historic properties. In addition, Section 4(f) regulations require FHWA to select the feasible and prudent alternative that avoids a use of a historic property. If no such alternative exists, FHWA must seek the alternative with the least overall harm to the resource(s).
Here are the three options for the bridge:
1. Rehabilitation in accordance with Secretary of the Interior’s Standards for Rehabilitation. The bridge would be rehabbed at its existing width. “Deteriorated elements would be replaced, in-kind, with stronger materials, in accordance with the AASHTO Guidelines for Historic Bridge Rehabilitation and Replacement. The concrete rails on the end spans would also be removed and replaced with new, context-sensitive, load-tested traffic rails. According to AASHTO Guidelines, decks and standard-design rails are not vital to maintain historical integrity of a structure. The metal rails of the truss spans would be cleaned and painted. Some sections of metal rail with severe collision damage may be replaced in kind,” the report states.
“As discussed in the referenced report, several elements of the bridge, such as gusset plates, floor beams and stringers, are in a deteriorated condition, such that in-kind replacement of the historic fabric of the bridge may itself result in an adverse effect to the bridge. The resulting rehabilitation would likely only bring the bridge up to a 15-ton rating. This alternative is not a long-term solution to the challenges affecting this structure, and provides for a 15-year design life for the bridge, at which time the structural condition will need to be addressed.”
2) Construct a new multi-beam superstructure and attach the pony truss panels to the superstructure and maintain the existing width. “The most viable option appears to be substitution of the truss spans (as the primary load-carrying element) with a new multi-beam steel superstructure with a concrete deck, to which the existing trusses would be re-attached using diaphragms at the lower chord panel points. In order to maintain the historic integrity of the original bridge, it is important that the trusses appear functional, so they will continue to support their own weight,” the report states.
“To support the new multi-beam main span and facilitate the removal of the fracture critical pier beams, the intermediate piers require complete reconstruction. The new piers will support the new beams for the main span, the existing beams for the approach spans, and the existing trusses. These changes will have an effect on the appearance of the bridge, and will likely be considered an adverse effect.”
3) Construct a new multi-beam superstructure and attach pony truss panels to the superstructure, widening it to 40 feet. “The most viable option appears to be to substitute the truss span as the primary load-carrying element with a new multi-beam steel superstructure with a concrete deck, to which the existing trusses would be re-attached using diaphragms at the lower chord panel points. In order to maintain the historic integrity of the original bridge, it is important that the trusses appear functional, so they will continue to support their own weight. The structure would be widened to 40-foot wide to meet ODOT’s design standards,” the report stated.
Keep in mind all these proposals become moot if the federal government doesn’t award a BUILD grant. But given the Pony Bridge’s continued importance to a federal highway and its prominent Route 66 link, one has to think its chances of landing the grant are good.
In a discussion of the options, it states about the second alternative:
The driver experience will be identical to the current feel. Maintenance costs and labor will be negligible, as the structure can be inspected on a two-year cycle. The solution provides for a 75-year design life. The truss panels will continue to support their own weight, minimizing the adverse effect by allowing the trusses to continue to perform a function for which they were intended.
For the third option, it states widening the bridge to 40 feet “would allow for a more safe facility as it would accommodate the current traffic in all forms, including the heavy truck traffic. The driver experience and ‘feeling’ of Route 66 would be diminished. This alternative would have the most substantial degree of adverse effect.”
The first option seems to find the least favor from road engineers because it would add only 15 years to the life of the bridge, and the weight limit would be increased to only 15 tons.
According to a news release from the Road Ahead Partnership, historic preservation specialist Anne Haaker said:
“Of the three alternatives, we prefer Alternative 1, rehabilitation in accordance with the Secretary of the Interior’s Standards for Rehabilitation (Standards). If this alternative is chosen, we believe that it could result in a finding of no adverse effect pursuant to a future consultation in accordance with section 106 of the National Historic Preservation Act. Alternatives two and three would both so significantly alter the historic fabric of the bridge that they would result in adverse effect findings during a formal 106 consultation. We definitely understand the longterm maintenance concerns if alternative one is carried out and hope to have further discussions with you about possible solutions. However, the loss in physical material in alternatives two and three would have a severe negative visual impact and probably not meet the Standards.”
The 106 reference pertains to Section 106, which gives people a chance to tell the federal government about historic properties and give their opinions about projects that may affect those properties.
Haaker makes a decent case, but I suspect option No. 2 would be a good compromise — especially if it greatly increases the lifespan of the bridge and keeps those distinctive pony trusses.
(Image of the Pony Bridge by Rhys Martin of Cloudless Lens Photography, courtesy of the Route 66 Road Ahead Partnership)