Walnut Lane Bridge repair project expected to begin in 2013; drivers should plan for 3.5-mile detour

In 1920, the Walnut Lane Bridge enthralled Christopher Morley, a Philadelphia journalist and man-about-town. In a column about a trip up the Wissahickon, Morley positively gushed:

“And then, just as one is about to sentimentalize up on the beauty of nature and how it shames the crass work of men, one comes to what is perhaps the loveliest thing along the Wissahickon — the Walnut Lane Bridge,” he wrote. “Leaping high in the air from the very domes of the trees, curving in a sheer smooth superb span that catches the last western light on its concrete flanks it flashes across the darkened valley . . . it is a thrilling thing.”

It’s 92 years later, and the view is still stunning but the bridge itself is in less-than-thrilling shape. Finished in 1908, the bridge structure and the roadway connecting Roxborough and Germantown both need repair; falling chunks of concrete have made parts of Forbidden Drive that travel beneath (“the last refuge of the foot and the hoof,” Morley declared) sometimes inaccessible to hikers and horses.

A state Department of Transportation plan for roadway replacement and extensive bridge repairs is moving ahead, meant to restore the Walnut Lane Bridge’s former glory — but will also mean a year-long headache for motorists.

A $7 million restoration project 

The project is moving into the design phase, and officials gathered at the Kendrick Rec Center in Roxborough Thursday to discuss the plans. The roughly $7 million restoration will involve: removal and replacement of the entire half-mile roadway; improvements to lighting, railings and pedestrian paths on either side; replacement of concrete balustrades with identical new ones, and repairs to drainage systems and eroded slopes below.

It sounds like a lot, but considering the age and heavy use of the bridge, which carries about 16,000 vehicles each day, it could be worse, said project manager Michael Cuddy.

“We’ve got a really good look at what’s wrong with the bridge now,” he said. Built on a wood framework of poured concrete without reinforcing steel, the main 230-foot span and four smaller spans are in good shape.

The roadway, and many of the bridge’s unique design elements, haven’t fared so well.

Early on, the city had plans to run a trolley line across the bridge, along a channel running down the center of the roadway. Those plans were scrapped, and the depression in the road surface filled in with several inches of cinders, now topped with several inches of asphalt applied over many decades.

Water infiltration has made the depression in the road worse, and it will all be pulled out and graded, dropping the road deck and creating more of a curb on either side.

“Essentially, the roadway is going to be about seven inches lower than it is now,” Cuddy said.

Special attention is being paid to the bridge’s aesthetics. New concrete balusters will be made from molds of the old ones, and the textured “Quimby finish” on the concrete surfaces will be replicated.

‘There’s still time to save this bridge’

Named for Henry H. Quimby, the city’s engineer on the bridge building project, the technique left the concrete what we might now call “distressed”: Each balustrade was removed from its wooden mold before fully dry, then the outer surface was brushed with wire bristles to reveal larger stones in the pebbled concrete mix.

“It’s part of the character of the bridge,” Cuddy said. “It will cost more, but this structure deserves something more.”

Period-appropriate lighting will replace the standard cobra-head light poles installed along the bridge in the 1970s, Cuddy said. By all accounts, the bridge should be lovely when finished, but things might get ugly in the meantime.

PennDOT can only detour traffic onto other state roads, Cuddy said, so motorists — still re-adjusting after lengthy Lincoln Drive detours — will take a 3.5-mile trip on Wissahickon, Midvale and Henry avenues to avoid the bridge construction.

Once design is complete, construction could begin in the summer of 2013 and stretch over two years, said Ryan M. Whittington, a civil designer for The HNTB Companies, working with PennDOT.

“The point is, there’s still time to save this bridge,” Whittington said, and its special place in the city’s history and heart is worth respecting. 

Morley put it this way: “Many poets have written verses both good and bad about the Wissahickon, but [the bridge’s designers] have spanned it with a poem that will long endure.” 

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