Innovation Fall 2025

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While traffic systems are engineered within a landscape of shifting variables, incomplete data, and evolving urban demands, engineers must also navigate infrastructure constraints and the unpredictability of human behaviour. And unlike calculating bridge weight capacities or a building’s water needs, anticipating traffic flow rarely offers the consistency of fixed inputs and expected outcomes. Engineering in the grey “We like to think of ourselves as being probably one of the greyest areas of engineering in the sense that, with certain relative specific exemptions, there’s very little specificity in terms of outcome,” said Gary Vlieg, P.Eng., FEC, Vice-President at Creative Transportation Solutions (CTS-BC), a traffic engineering firm. “For example, if you’re designing a bridge, you know what the load has got to be and you can design for that load. If you’re designing a water network, you know that you have to deliver 150 liters per second minimum for fire flow, and you run through the calculations and away you go.” Vlieg highlighted the persistent capacity issues over the last several decades with Highway 1 in BC as an

We like to think of ourselves as being probably one of the greyest areas of engineering in the sense that, with certain relative specific exemptions, there’s very little specificity in terms of outcome. Gary Vlieg, P.Eng., FEC, Vice-President CTS-BC

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example. The Fraser Valley portion of the highway was designed in the 1950s and was completed in 1962. The area’s population boomed over the next few decades, with some municipalities such as Surrey seeing their population grow by a factor of up to five, and “basically nothing was done with it for the next 60 years,” Vlieg commented. Traffic updates for the Port Mann bridge would regularly let drivers know traffic was backed up to 200th Street, roughly 20 kilometers away. “Transportation is one of those weird things where we can calculate capacities and all the rest of it, but people’s capacity to absorb delay,

for lack of a better term, sometimes astonishes me,” Vlieg said. In other words, how do you predict how long thousands of drivers will be willing to sit in hours-long gridlock? As a result, predicting a road or a bridge’s usage five, 10, or 15 years into the future is “an educated guess at best,” he said. Additionally, a community’s appetite for building out traffic infrastructure prior to demand is generally outcompeted by higher priority items. “A lot of communities have made the decision to invest [in traffic infrastructure] after the demand is there, not before the demand,” Vlieg said. Yulia Liem, P.Eng., PTOE, is regional manager, BC, principal, and board member with Bunt & Associates Engineering Ltd. She explained that when a municipality wants to densify or build a new neighborhood, decision makers “have to make sure the infrastructure works,” including having sufficient access to water, gas, and power to accommodate the new residents. But projected traffic capacity is less tangible than other infrastructure, making traffic planning more of an iterative process rather than a formulaic one.

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Fall 2025

Innovation