The Walnut Lane Bridge: Poetry in Poured Concrete

Walnut Lane Bridge 4-12-1907 (
Walnut Lane Bridge 4-12-1907 (

Sauntering in the deep recesses of Fairmount Park a century ago, Christopher Morley and his know-everything guide were just about “to sentimentalize upon the beauty of nature and how it shames the crass work of man” when they came upon “what is perhaps the loveliest thing along the Wissahickon – the Walnut Lane Bridge.”

“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 as nobly as an old Roman viaduct of southern France. It is a thrilling thing, and I scrambled up the bank to know down the names of the artists who planned it. The tablet is dated 1906, and bears the names of George S. Webster, chief engineer; Henry H. Quimby, assistant engineer; Reilly & Riddle, contractors. Many poets have written versus both good and bad about the Wissahickon, but Messrs. Reilly & Riddle have spanned it with the poem that will long endure.”

As Chief Engineer of the Department of Public Works and Bureau of Surveys, Webster “had long argued that a high-level bridge between Roxborough and Germantown would eliminate a hilly five-or six-mile detour into the Wissahickon Creek valley.” He considered proposing “a steel viaduct with a wooden floor,” but thought better of it. Webster envisioned a bridge more appropriate for the “natural park scenery of rocky and wooded slopes.”

In 1905, City Council grated Webster his wish, authorizing construction of an elegant arched bridge, and allocated funds to unite the two neighborhoods “at the narrowest point of the ravine, along the line of Walnut Lane.” The project would begin July 5, 1906 and lasted two dramatic years.

Walnut Lane Bridge 1910 (
Walnut Lane Bridge 1910 (

When complete, Walnut Lane would be the largest concrete bridge in the world, inspired “structurally and aesthetically” by the Pont Adolphe over the Pétrusse River in Luxembourg, completed only two years before.

Forty thousand tons of concrete never looked so much like a line of poetry. Giant arches stretched across the ravine providing a path more than 145 feet above “the most picturesque portion of the Park.” It seemed as if the bridge was “literally springing from out the foliage of the tree tops.”

Reilly & Riddle poured concrete arches atop a gigantic falsework of steel and lumber that, “for the sake of economy” was used twice, once for each rib. In a demonstration of skill, faith and engineering finesse, “four temporary concrete piers in the stream bed supported the falsework and provided a glide path for shifting it from under the first finished rib to where the second one would rise. To move the falsework, thirty men operated a massive ball-bearing jack at pier level, nudging the 900-ton falsework 34 feet, inch by inch. The operation took three days. At the conclusion of the job, Reilly & Riddle demolished the concrete piers with dynamite, returning the creek bed to nature.

“It is the greatest bridge of its kind in the world,” glowed Mayor John Reyburn at the dedication, where school children from Roxborough, Manayunk and Germantown sang in unison. “It was conceived and executed by our own men,” he boasted, proudly suggesting that fact alone made it worth the price. Never mind that it’s status as the largest concrete arch in the world was quickly surpassed by the New Detroit-Rocky River Bridge in Cleveland and the Grafton Bridge in Auckland, New Zealand. In a city of makers, Philadelphians had made more than a bridge, they had created “one of the wonders of the world.”

Whatever became of all that construction debris, in particular the 900 tons of lumber used to build the temporary falsework? On March 29, 1908 an advertisement in the Inquirer put out the word: 300,000 feet of new pine lumber, “all sizes and lengths to 30 feet long” was available at the bargain rate of $14 per thousand feet. Come to the bridge, take your pick, haul it away. The advertisement didn’t bother to specify which side of the bridge, Germantown or Roxborough. But since the bridge had opened, that detail no longer mattered. East and West were almost one and the same.

[Sources: Walnut Lane Bridge. Pennsylvania Historic Bridges Recording Project -II, Historic American Engineering Record, (PDF); The Walnut Lane Bridge;J. A. Stewart, “The New Bridge Over the Wissahickon at Philadelphia,Scientific American, November 30, 1907; George S. Webster and Henry H. Quimby, “Walnut Lane Bridge, Philadelphia,” Transactions of the American Society of Civil Engineers, Vol. 65, 1909; The Philadelphia Inquirer, “Mammoth Arch to Span Wissahickon,” March 20, 1906;  The Philadelphia Inquirer, “New Walnut Lane Bridge is Dedicated to City’s Use,” December 17, 1908.]