After I-25 Was Widened, It Filled Back Up With Cars in Less Than 5 Years

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Image: SWEEP

Colorado spent $1.2 billion to widen I-25, and all it got was more traffic and no congestion relief. Why does Governor John Hickenlooper think that widening I-70 will be any different?

In this chart, you can see why spending billions to widen highways is a shortsighted, ineffective way to deal with people’s travel needs. About two years after the widening wrapped up, I-25 was just as congested as it was when construction started, and within five years it was more clogged than ever.

The term for this is “induced demand.” When cities make more room for cars, people drive more. Usually within a few years, any initial improvement in congestion levels has evaporated, and drivers start agitating for more lanes.

A stunning recent example comes from Houston, where Texas DOT spent nearly $3 billion to take the Katy Freeway from eight lanes to 23 in some sections. Traffic was as slow as ever six years later.

In I-25, Denver has it’s own (smaller) version of the Katy Freeway. Colorado DOT finished widening the highway by as many as four lanes in 2006 for the project known as T-REX. In a few years, congestion on I-25 through south Denver reached pre-construction levels, according to a report by the Southwestern Energy Efficiency Project and the Colorado Public Interest Research Group.

“The state spent $1.2 billion on this road widening, with no long-term benefit in lowered congestion,” the authors write.

Hickenlooper is ready to build a massive boondoggle of an expansion on I-70 even though he learned all about induced demand in 2004 at the Mayors Institute on City and Design.

With I-25, there’s proof right under his nose that highway widenings aren’t worth the expense. And yet, under Hickenlooper Colorado DOT keeps repeating the same mistakes.