Gwynedd Train Station

Saturday, July 13th, 2013 by Jazz Pared

Challenge

The Southeastern Pennsylvania Transportation Authority also known as SEPTA had settlement issues on two rail lines at a road crossing located in Ambler, Pennsylvania. The 14” thick concrete slabs that were supporting the track had settled in areas as much as 1-7/8” inches. For passenger trains, safely navigating this area of the train tracks required a 40 mile per hour reduction in speed. SEPTA’s main concern was for the safety of their passengers, as continued settlement could lead to derailment in the future. Also, minimizing the disruption to train schedules during repairs would require keeping one of the 2 tracks in service at all times. Slab replacement was not as option due to the expense and budget given to the SEPTA crew. Time and disruption to the street traffic and SEPTA trains were also taken into consideration when reaching out to companies to fix the sunken and settled concrete slabs. Previous attempts to lift settled rail slabs with mudjacking were not precise and were prone to washouts over time.

Solution

SEPTA chose Foundation Supportworks of New Jersey and the PolyLEVEL Polyurethane Injection System to resolve the sunken concrete problem. PolyLEVEL is a two-part urethane that, when combined, expands into a waterproof, rigid foam that is used to fill voids, stabilize slabs, and lift sunken and settled concrete. The installation of PolyLEVEL began by drilling penny-sized injection holes into the concrete slab. Next, using specialized equipment, approximately 500 hundred pounds of PolyLEVEL was injectedbelow the slab through a total of 96 injection areas. The rail elevation was monitored continually throughout the job with surveying equipment, and both the rail and slab were returned to their original position. With a compressive strength of 100 pounds per square inch, PolyLEVEL provides the necessary strength to support extremely heavy loads. With the use of the PolyLEVEL system, Foundation Supportworks was able to stabilize and lift the settled concrete back to its original elevation with no concern of eventual washout. The project was completed in a total of 8 hours over the span of two days, and the road and tracks remained open to traffic and crossing pedestrians. Two hours after the track was lifted back into place, heavy loads were applied to the raised track, and no movement was observed visually or with surveying equipment. The SEPTA trains, pedestrians and drivers were able to walk and ride over the lifted slabs just minutes after the installation was complete. Overall the SEPTA team was extremely pleased with the results as well as the efficiency and professionalism of the Foundation Supportworks of New Jersey crew.