Gwynedd Train Station

Friday, July 19th, 2013 by Jazz Pared

Challenge

The Southeastern Pennsylvania Transportation Authority decided to contact Quality Concrete when they had settlement issues on two rail lines at a road crossing in Ambler, Pennsylvania. The Gwynedd Train Station had 14” thick concrete slabs supporting the track with settled areas as much as 1-7/8” inches. For passenger trains, safely navigating this area of the tracks required a 40 mile per hour reduction in speed. SEPTA’s main concern with the project and repair was for the safety of their passengers, as continuedsettlement could lead to potential derailment. Additionally, minimizing the disruption to train schedules during repairs would require keeping oneof the 2 tracks in service at all times. Slab replacement was not as option due to the expense,time and disruption it would cause to both street traffic and SEPTA trains. Previous attempts to lift settled rail slabs with mudjacking were not precise and were prone to washouts over time. With the use of the PolyLEVEL System from Quality Concrete, SEPTA was able to meet all of their goals and fix the problem at hand.

Solution

SEPTA chose Quality Concrete and the PolyLEVEL Polyurethane Injection System to resolve the 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 lastly lift sunken and settled concrete. The installation of PolyLEVEL began by drilling a total of 96 penny-sized injection holes into the concrete slab. Next, using specialized equipment, approximately 500 hundred pounds of PolyLEVEL was injected below the slab through the injection areas. The rail elevation was monitored continually with surveying equipment, and in the end both the railand slab were returned to their original position. With a compressive strength of 100 pounds per square inch, the PolyLEVEL system provides the necessary strength to support extremely heavy loads. With the use of the PolyLEVEL system, Quality Concrete was able to stabilize and lift the settledconcrete back to its original elevation with no future concern of eventual washout. The total project was completed in 8 hours over the span of two days, and the road and tracks remained open to traffic and 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 surveyingequipment. SEPTA was extremely pleased with the results as well as the efficiency and professionalism of the Quality Concrete crew.