Landenberg Bridge De-Listed From National Register

We were disappointed to learn that, as of March 23, 2010, the Landenberg Bridge has been de-listed from the National Register of Historic Places. The bridge had been on the National Register since 1988 when it was nominated for its engineering significance, both for its cantilevered sidewalk and for being a Pratt pony truss bridge - an unusual style in southeastern Pennsylvania.

The Pennsylvania Historical & Museum Commission (PHMC) has ruled that since the work currently in progress will change the bridge from functioning as a Pratt pony truss bridge to functioning as a girder bridge, that it no longer has National Register significance.

After the bridge was closed in 1998, the decision was made that the bridge needed to be strenghened in order to meet modern needs, especially for fire and emergency equipment which require a 40 ton capacity. The bridge had been originally designed for horse and buggy traffic in 1899. In 1934 it was strengthened to 9 tons to meet that day's motorized traffic needs, and that was pretty much the limit for what a Pratt pony truss bridge of that size could support. For the current project, the only way the engineers could suggest to provide the necessary increase in capacity was by adding the girders underneath. This approach had been successfully use in the rehabilitation of the Pratt pony truss Mill Road Bridge near Kennett Square.

It had been understood, from that the Secretary of the Interior's definition for Rehabilitation on the NPS website, that structural additions such as this were allowed:

Rehabilitation is defined as the act or process of making possible a compatible use for a property through repair, alterations, and additions while preserving those portions or features which convey its historical, cultural, or architectural values.

however PHMC has ruled otherwise. PHMC did not given us any indication while the project was in design that this approach would be unacceptable.

There may be some possibility of getting the bridge re-listed, but it is not clear how long that will take or if PHMC will be receptive.

PHMC's letter of explanation is available here.