Benchmark traffic analysis flawed; new report provides more comprehensive measurement - Metropolitan Planning Council

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Benchmark traffic analysis flawed; new report provides more comprehensive measurement

New analysis underscores value of transportation investments that connect people to desirable places

(Chicago) … A new report from CEOs for Cities found that the widely used benchmark for measuring metropolitan traffic problems – Texas Transportation Institute’s (TTI) annual Urban Mobility Report – is faulty, and that the secret to reducing the time Americans spend stuck in traffic has much more to do with how we build our communities than how we build our roads.

The nonprofit Metropolitan Planning Council (MPC) agrees with the report’s critique of the TTI’s annual Urban Mobility Report. TTI’s methodology, which focuses on travel speeds – to the exclusion of trip destinations – makes it an unreliable guide to understanding the nature and extent of transportation problems in Chicagoland and other U.S. metropolitan regions.

Put another way, TTI’s annual report prioritizes “mobility” over “accessibility” as the primary measure of a successful transportation system.  Mobility, a two-dimensional calculation, only factors in speed. Accessibility, a three-dimensional calculation, not only considers how fast a vehicle travels, but also where it’s going and how quickly it reaches its destination, explains Peter Skosey, MPC vice president.

“Traffic is inevitable — but not all congestion is bad,” said Skosey. “If a person is stuck in the most horrendous traffic imaginable, but he only has to commute one block to get to his job, then his mobility is terrible, but his accessibility is actually quite good.”

“On the other hand, if he’s cruising in moderate traffic but the distance between his home and work is 70 miles, his mobility isn’t poor, but his accessibility is awful,” he added.

Indeed, CEOs for Cities’ report, Driven Apart: How sprawl is lengthening our commutes and why misleading mobility measures are making things worse, ranks how long people are stuck in traffic in the nation’s largest 51 metropolitan areas. Some of CEOs for Cities’ rankings are nearly opposite of those listed in TTI’s 2009 Urban Mobility Report.

Accurate data to guide transportation investments is especially critical at a time when state and federal agencies are strapped for cash and transportation decision makers must do even more with less funding. Local and regional planning that reduces transportation demand, as well as smarter spending and strategies that make the most of existing infrastructure, such as congestion pricing, should guide future investments, added Skosey.

Focusing on travel speeds rather than distance to destinations also downplays the significant role transportation plays in supporting healthy metropolitan economies.

“Bustling streets are a sign of thriving communities,” said Skosey. “The more people and goods move through a neighborhood, city or region – up to a point – the healthier its economy.”

Once a threshold is reached, he added, the cost of adding another vehicle to the road – in terms of delay and other drawbacks of traffic – outweighs the benefits to society.

MPC’s groundbreaking 2008 report, Moving at the Speed of Congestion, quantified the cost of excess traffic congestion in Chicago and its six surrounding counties – Cook, DuPage, Kane, Lake, McHenry, and Will – at $7.3 billion a year in wasted time and fuel and environmental costs. CEOs for Cities study reinforces MPC’s 2008 findings that land use is a critical factor in making transportation investments.

Driven Apart drives home how we can improve our daily lives by investing in attractive transportation options that connect people to desirable places,” said Skosey. “Every trip has a destination, and it’s important that we fund new roads, public transit, sidewalks and bike lanes that get us where we need to go.”


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