What, to the casual observer, seems like an ordinary bridge over a small creek, is turning out to be quite extraordinary, and may become one for the record books.
PennDOT is replacing the Harrity Road bridge across the Pohopoco Creek in Franklin Township with what they believe is the longest bridge of its kind in Pennsylvania.
The bridge, a concrete "T"-beam design, stretches 168 feet, 8 inches in a single span. It uses mammoth eight-foot deep beams which also are thought to be record setters. PennDOT representatives believe it is the longest single span concrete "T"-beam bridge in Pennsylvania.
The new bridge replaces a two-span concrete box beam design. The two spans were tied together at a central pier. The old bridge has been removed.
According to Mike Keiser, assistant district executive for design in District 5, the bridge was replaced as part of PennDOT's bridge replacement program because it had outlived its economical life, which means that it would cost more to maintain the structure than to replace it.
When the new design was considered, there was a desire to do away with the central support for environmental and cost reasons. The resulting design led to the single span bridge design that required eight-foot-deep beams.
The beams are so deep being just a few feet above the creek that local business owners are concerned about flooding.
Jeff Wartluft, a local canoeist, is also concerned because the low clearance made the creek unsafe for boating. Signs have since appeared confirming Wartluft's observation. The signs, located just upstream and downstream of the bridge, read, "Danger Low Bridge No Boating."
At the speed that the creek typically flows, and with no convenient place to exit the creek, the upstream signs are basically cautioning a paddler to "duck," although they would be useful to anyone scouting the river if they would see the sign before considering paddling the section.
PennDOT officials, in conversations with the PA Fish and Boat Commission and the U.S. Army Corps of Engineers, decided that the 1.5-mile section north of the bridge, which begins at the outflow from Beltzville Lake should, because of the limited clearance under the bridge, be deemed not navigable.
As the flow into the creek above the bridge is largely controlled by the Beltzville Lake Dam and only receives about 1.5 miles of runoff, PennDOT's water flow analysis indicated that there was minimal flood risk. PennDOT spokesman Sean Brown noted that even with the unusual amount of rain this year, the creek did not reach the bottom of the bridge.
Keiser noted that even if the water came above the bottom of the bridge beams, the beams were designed to handle the load.
Operators of the Beltzville Dam have begun controlling the reservoir's outflow to maintain normal levels below the bottom of the concrete "T"-beams.