No Loop, No Problem - Testing unbuilt infrastructure

 

 

You would never buy a product that hasn’t been tested. Whether it’s a home appliance, a vehicle or any retail item, it’s important to know that the items we buy are tested to guarantee the quality of their construction.

The same principle applies when building a new transit line. We want to know that every new piece of infrastructure works exactly as intended, and that it has been tested for operational readiness on opening day.

Bus loops - the large terminals at transit stations that serve as the final stop for multiple bus routes - are one such piece of infrastructure. The design of a bus loop requires precise measurements to allow vehicles space to navigate smoothly in a busy, confined space. Bus loops require thorough testing to guarantee that infrastructure issues won’t impede traffic flow, but they need to be built right the first time, as a rework would be costly and complex. This presents a challenge; how do you test a bus loop that has yet to be built?

The answer – build a mock-up using temporary barriers!

First, a large, empty paved space appropriate for large amounts of bus traffic is located. Using precise measurements from our design documents, we draw chalk lines and lay down traffic cones to create the exact layout of the planned loop. Surveyors measure every section of the build to ensure that we’ve matched the design, down to the centimeter.

Next, comes the actual testing. Buses drive in and out of the mock loop, simulating what an actual operation would be like on any given day. All potential vehicle paths are tested by at least one TTC bus, and some paths use multiple buses in a row to recreate a rush hour scenario. It’s just like a live bus loop, but without any passengers.

When testing is complete, representatives from Metrolinx, TTC and Crosslinx Transit Solutions (our constructor) review the data and provide input on areas of improvement. Together, necessary changes are finalized and new designs are drafted.

“It may seem like overdoing it to some, but these additional pre-construction tests are a very important step of the process,” says Brad Focken, Design Manager for the Crosstown’s Eastern Works. “Using mock-ups, we can minimize rework, saving time and money. Moving a few pylons and re-measuring is cheaper than demolishing sections of concrete and re-pouring.”

So far, bus loop testing has occurred for Kennedy Station (on the Kennedy Station grounds) and the future Science Centre Station (on Canada’s Wonderland grounds), both yielding positive results.