In late November 2017, San Diego’s Metropolitan Transportation Service (MTS) inaugurated a new, high-efficiency wheel truing pit to keep MTS rail cars rolling smoothly. To eliminate any water penetration from the pronounced hydrostatic pressure at the site, the PENETRON System was chosen over a conventional waterproofing membrane for the wheel truing pit structure. The choice saved construction time and money.
An underfloor truing pit – outfitted with a metal milling machine – can simultaneously re-profile wheels of passenger or freight cars, while the wheel set is attached to the rolling stock. The new MTS wheel truing pit is dedicated to maintaining the Red Line trolley rolling stock.
“A truing pit helps keep the metal wheels true so the cars roll smoothly,” explains Christopher Chen, Director of The PENETRON Group. “After the procedure, the MTS Red Line trolley cars roll out and run very smoothly down the tracks.”
During excavation of a new wheel truing pit at the MTS maintenance yard, the specifications outlined the depth of the pit to be almost three feet under the water table. When the general contractor (Western Rim Constructors) began digging, water poured in quickly, filling the bottom of the hole. To finish the excavation, seven dewatering pumps were installed to drain the area day and night to keep the water out. Eventually, preparation of the pit was completed.
Original project parameters specified installation of a waterproofing membrane. However, the project manager looked for a better solution to prevent water penetration through concrete.
Thanks to a recommendation from Superior Ready-Mix Concrete in San Diego, Mike Domanski, Project Manager at Western Rim Constructors, asked PENETRON for a solution. He soon learned that, if PENETRON can keep this truing pit dry, then PENETRON will be able to waterproof any project.
Challenge accepted! The PENETRON solution included a range of crystalline products: PENETRON ADMIX was used to treat all the concrete for the footings, slab and walls of the truing pit; PENEBAR SW sealed all cold joints; PENECRETE MORTAR patched any remaining cracks and imperfections in the new structure.
“As this was an update to an existing pit, there were several existing challenges, transitional changes and odd configurations that had to be addressed.” adds Christopher Chen. “Treating the concrete with PENETRON ADMIX and other components of the PENETRON System gave the contractor a simplified, single source and faster solution.”
When PENETRON ADMIX is added to the concrete, it reduces permeability by permanently sealing micro-cracks pores and capillaries, effectively protecting the concrete against water penetration, even under high hydrostatic pressure – as found at the MTS construction site.
“Ultimately, the recommended PENETRON technology not only helped reduce construction time by more than five days, but the general contractor was also able to achieve substantial cost savings,” says Christopher Chen.
Finally, Mike Domanski pointed out, “The pit is as dry as a bone.”
Permanent seal: This close-up of the side wall area of the San Diego MTS wheel truing pit shows where the PENEBAR SW waterstop will seal the resulting construction joints in the new concrete.
Before the pour: A view of the preparations prior to pouring the PENETRON ADMIX- treated concrete for San Diego MTS’ wheel truing pit to counter the challenge of high groundwater at the site.
Better than a membrane: The pour is done and the new PENETRON – treated MTS wheel truing pit is dry and durable – quicker and more cost- effective than the originally specified membrane.
