Valley Forge Laboratories, Inc.

Location:   Frankford & Bustleton Avenues, Philadelphia, PA

Client:   SEPTA

Description :
This high profile SEPTA project involves the rehabilitation of the Frankford Transportation Center in the northeast section of Philadelphia. Frankford is the terminus of the Market-Frankford elevated line (SEPTA’s most heavily traveled line) and the Terminus for the northern half of the Trolley-Bus System. The Center includes a repair shop for the Market-Frankford Line and repair shops for both the trolley-bus fleet and some of the bus fleet.

The proposed structures include the following:

• 1000 foot long elevated guide-way for the Market-Frankford El
• 250 foot long terminal building with deep basement
• Four level parking structure
• Temporary trestle
• A new building at the corner of Bridge and Pratt Streets
• Bus depot additions

VFL’s subsurface investigations included 43 test borings and laboratory testing of soils and rock. Geotechnical design challenges unique to this project included high column loads, shear and moment reactions for the guide-way; variable top of rock elevations and rock qualty; weak fill and high groundwater levels; and project areas with tight overhead working conditions. These complications necessitated the design of six different foundation systems for the support of the various structures including, a basement mat, spread footings with in-place stabilization of weak fill, 100-ton drilled in place mini piles, 60-ton driven steel H-piles, five-foot diameter drilled piers with five foot long rock sockets.

The use of different foundation systems required detailed attention to potential differential settlements.