October 07, 2013

Topping Off at Dilworth Plaza

A construction crew spreads and smooths concrete to form the surface at Dilworth Plaza.

In the early morning hours of July 11, a major concrete pour raised progress on the Dilworth Plaza renovation to a new level—quite literally. Previously, work on the plaza at Philadelphia's City Hall had been restricted to the transit concourse below ground. Now, with the addition of a roof over the north concourse, the floor of the plaza has been formed, and work can continue on the two levels simultaneously.

Beginning at 3 am to avoid the heat of day and the traffic that converges on City Hall, fifty-five trucks circled the city, bringing concrete from a site near the Philadelphia airport and delivering it to the plaza every ten minutes in a carefully orchestrated sequence designed to prevent the material from hardening during the process.

A remote-controlled arm pumps concrete from the trucks.
A remote-controlled arm pumps concrete from the trucks.
A remote-controlled arm pumps concrete from the trucks.

On August 30, a second concrete pour formed the slab below the fountain, containing all the piping necessary for the water feature as well as a public art installation called Pulse that employs columns of illuminated mist to trace the lines of transit. On October 5, the last of the structural slab over the concourse was poured.