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.

  • Andrew

    It’s interesting to see the I-70 project getting compared to I-25’s TREX. I would be interested in seeing a study that found induced demand, leading to congestion, on tolled / managed lanes. Lanes that in fact have variable pricing structured to maintain free flow of traffic. The examples I’ve seen cited here are all expansions with free general purpose lanes. There are no free lanes getting added to I-70. It’s like the good old saying, comparing apples to oranges.

    • Andrew

      I forgot to mention a couple of things about TREX that haven’t been mentioned on this blog post. TREX, actually costing 1.67 billion, wasn’t all dedicated to highway widening. $879 million was for the new light-rail and $795 million went towards the highway. So saying that $1.2 billion (which isn’t the right number anyway) was used just for road widening is very misleading. (Source: RTD)

      Secondly, while it is true that traffic reached pre-construction (1999) levels in 2008, the three counties TREX goes through added over 250,000 people in that time! All things considered, that’s not too shabby.

      • Anthony

        Good comments.
        I will push back gently on the added population as that’s part of the induced demand. Of course we can never know for sure if the growth would have occurred without the widening, but one of the key things that was repeatedly drilled into my head in my Masters of Real Estate Development program is to follow the transportation investment. If I-25 weren’t widened, would 250,000 new people live in the corridor? I hypothesize that number would be much lower, especially given the amount of development that occurred between the announcement of the project and completion of the project. This is the essence of induced demand. The implication is that our decision on how to invest in our infrastructure directly led to increased growth on the urban fringe.
        The philosophical question, then, is this something we should be encouraging? I’d argue fiscally, socially, and environmentally, exurban growth is catastrophic and should be a last choice and our local government entities shouldn’t be “investing” in infrastructure that promotes this type of growth pattern. Obviously others feel other values are held higher than the three I listed and support this type of growth.

        • enguy

          We can’t know for certain if this growth would have happened without I-25 widening, but we can compare against other cities in the area that didn’t have any highway lanes added. The best comparison is probably along north I-25 in Thornton/Broomfield/Westminster which wasn’t expanded until the opening of express lanes this year. As far as I can tell with limited data (from ), from 2000-2010 Westminster didn’t grow much, but Broomfield and Thornton added way more people than comparable cities in the south end (Centennial and Lone Tree). This suggests that the growth the Denver area saw during the T-REX time frame had more to do with zoning and other factors than it did to do with highway widening.

        • Ronald T Milam

          In general, roadway capacity expansion within a corridor only influences the regional allocation of growth. Individual projects are not substantial enough to change regional population and employment growth totals although Duranton and Turner (2011) did find a small positive effect on regional net migration associated with increasing lane miles – So one key question is whether the roadway capacity expansion was serving a desired land use pattern in the corridor or whether it induced an amount or form of growth that wasn’t anticipated or desired.

      • murphstahoe

        Without the widening, those counties may have added fewer people (but they would have to end up somewhere else) – or better yet the jobs might disperse to places where people live because of the congestion. Save the 1 billion on the freeway, and billions of dollars of gasoline.

        • FunctionForm

          We know today that the front range population estimates are 8 million people by 2050. That may be a conservative estimate. CDOT needs to be planning around those numbers.

      • cc

        No actually, that’s extremely shabby. All the widening did was enable more sprawl development.

    • Chris

      I guess we just need to look at I-70 in the mountains where they added a toll lane. Congestion is exactly the same, except for those that can afford to pay the price to use the toll lane.

      Might be better to explore how the A-line will change the habits of people living along I-70. It might also be important to examine how I-70 destroyed neighborhoods and we could restore them or keep them broken?

      They highway could go through an industrial section of Denver and loop to the north avoiding neighborhoods or we could keep the status quo for a future that does nothing better for us.

      • Anthony

        The I-70 toll lanes are working almost exactly as anticipated in this regard. The only proven way to maintain an expected level of service that keeps traffic congestion at bay is to charge a price that balances supply and demand. This will be I-70 east’s fate as well. Three lanes congested, two flowing. Until all the lanes are charged, you’ll have the option to travel slowly for “free” or travel faster for a fee. Failure to charge at all would result in I-25 part duex.

      • enguy

        Actually, congestion has dropped even in the non-toll lanes of I-70, particularly during peak times:

      • TakeFive

        The route to the north was considered during the 12 year analysis. It was uneconomical and passing an increased fuel tax in Colorado seems to be a non-starter. If anybody had come up with the necessary funding I’m sure they may have been more willing to go there.

  • Jeffrey Baker

    Volume / capacity seems like a misleading metric here. Isn’t the total throughput higher, because the capacity is higher? So in some sense you could say the money was spent to increase capacity rather than to relieve congestion.

    • MT

      Unfortunately DOT’s still use volume/capacity as a measure of performance.
      They will see that the volume/capacity ratio is too high, and say the road needs to be widened again so that traffic can move faster. Then it will fill up with traffic, and they will want to widen it…

      • TakeFive

        In the case of CDOT, they don’t dictate needs; they respond to the wishes of the public, the voting public. With respect to the T-REX portion of I-25 afaik there is no more ROW. But as Mr. Bhatt has stated, technically, they can engineer whatever the majority of voters wants and is willing to pay for.

        • MT

          When was the last time we got to vote on a highway expansion? I don’t remember.

          • TakeFive

            T-REX was approved by voters in Nov. 1999.Voting on each project of course would be silly. If you have questions about how CDOT functions and their mission I’m sure their website could provide a lot if insight.

            I am a bit biased but I think CDOT is one of the better functioning state DOT’s. They suffer from a lack of funding compared to many growing states but that is not CDOT’s fault.

          • MT

            If they had more funding they’d be widening more highways. Better that they don’t.

          • The last time the State voted on widening freeways was in the 2002 election year. The ballot initiative was for a big bond issue that would have been paid off by extra taxes.

            It went down to defeat by a 48-52 margin Statewide, though Metro-Denver voters would have approved it.

            What I can’t understand is why the urban Front Range doesn’t enact some local extra taxation to fund our own transport deficiencies without having to get everyone Statewide to vote to approve it.

          • MT

            At least RTD is locally funded.

          • RTD is not locally-funded, in-fact only pays 22.77% of its operating costs at the farebox. More than half their operating cost comes from Federal urban mass transit funds.

            What does RTD charge for a express bus these days? $4.50? If RTD wasn’t heavily subsidized they would have to charge almost $20/passenger to break even.

          • FunctionForm

            We haven’t. They haven’t taken anything to a vote because highway funding doesn’t poll well. At least not yet.

      • FunctionForm

        I would agree with that except that Denver and Colorado have done very little to increase capacity in 60 years. Yet the population is substantially larger and continues to grow.

        • MT

          I think highway capacity has increased enormously in the last 60 years.
          I-70 didn’t even exist yet, I-25 has been widened many times in different areas, Santa Fe has basically become a freeway, C470 was built, E470 was built, the highway expansion has been constant.

          • 60 years ago Metro-Denver’s population was only 1/6th of what it is today too. Even worse, if the Metro-area wants to become a real big city on the scale of a top-10 urban area, our transportation system regardless of whether road or rail is grossly deficient too.

  • TakeFive

    Just curious, whoever asserted that increasing road capacity guarantees smooth sailing forever? I thought the whole purpose for expansion was to accommodate current and future growth. This whole “induced demand” thingy is one of the sillier notions I’ve heard of.

    • Anandakos

      In Europe cities far larger than the Denver Metro area produce 1/3 to 1/5 the VMT per day because they make the effort to provide people with an alternative. Not everyone in the world (in fact most people) are “gearheads” who love driving as an activity. For most people, it’s a means to an end.

      So if quality (frequent, reasonably comfortable, and reliable) transit within walking distance at both ends of their trip — even if transfers are required — they use it. But that means you can’t have the sterile suburban neighborhood model to which western US cities have become addicted.

      Cars are GREAT for the occasional trip to the country, but they’re fundamentally destructive as the basis for most commuting trips.

      • FunctionForm

        European cities were built in a different time with much higher densities that Colorado. What works there does not work here. We need to create our own solutions based on our needs rather than make assumptions about how we should look like Europe.

        • If you like Europe so much there are several non-stop flights to Europe from DIA to choose from

  • If congestion is the problem identified, the solutions are going to be all about congestion relief. (which leads to typical approaches)

    What I’d like to see more regions do is put a dollar figure out there (like $750 million) and ask people which of 4 or 5 choices would you most rather spend that amount of money on. The public purse does have limits, and when it’s used for highway expansion, it means less available for other needs. Of course the public might in the end choose the big roads over schools or parks or public safety or health care, but at least the options could be presented.

    • Andrew

      Correct me if I’m wrong, but isn’t the I-70 project getting funded by the bridge enterprise funds that people pay with their car registrations? Funds solely dedicated for roads? Last time I checked you can’t just reallocate that money to something completely different. So if you don’t have a car, none of your money is going towards I-70 anyways…

      • I don’t know the funding details, but it’s immaterial. I’m not talking about the ins and outs of DOT processes nor precise funding mechanisms. I’m talking about having a different conversation, and then shaping funding mechanisms accordingly. Most of how we do things is simply inertia from decades-old ideas anyway – not written in stone tablets.

        • TakeFive

          IMO, there has been a ton of advances over the decades. Not sure how closely you’ve followed this?

          • Just from a distance, and I’m sure CDOT is more advanced than most. But the conversation at all regions frustrates me. There’s an assumption people by and large support this kind of spending, but it’s always presented in the bubble of the transportation world, where money is spent like there’s an endless honey pot.

          • TakeFive

            How many of the public presentations over a dozen years did you participate in? Have you read the EIS’s. I’ll admit I’ve only read parts of them but they are there to read.

    • TakeFive

      A lot of analysis and public feedback was gathered over a period of a dozen years. There’s a pretty rigorous procedure that CDOT must follow and did. Actually having to spend 12 years on an interstate route that is vital to commerce and in obvious need of a fix seems like wasted time to me.

  • zoom314

    Los Angeles County in California did this, widen a fwy, then watch it fill up in days to a month, now LA is building Light Rail instead(since 1990, uses Catenary for power), Light Rail combined with Bus routes to feed Light Rail, can soak up traffic that fwys can’t handle and reduce congestion, fwys(Interstates) were great as long as almost no one owned a car, but soon the limits have become apparent. Oh and no one is being forced to give up their car, that would be silly.

    • Unless you are willing to pay a good deal more for trains and buses that RTD charges now we are stuck with our current system for another 20-25 years.

      So, would you rather enact growth restraint, which will drive growth elsewhere, or would you rather fund growth served by new highway capacity?

      How many lanes do I-10, I-210, and CA-60 have combined? 24 lanes? Now add CA-91 with its median toll lanes. Imagine having 36 freeway lanes of capacity just serving one side of an urban area, plus trains?

      Combine all the north-south freeways and parkways in the Bronx, how many lanes combined are there? I-87, I-95, plus the Hutch, the Bronx River Parkway, and the Taconic Parkway, plus three different Metro North rail routes?

      Frankly if Metro-Denver wants to become a big urban area our transportation system is grossly under-capacity. Why think small? Do whatever it takes to keep growing lest some other city end-up with growth we could have had.

  • John Thompson

    There’s no mention that I can see here about how one of the major drivers of the I-70 project in North Denver is driven by the need to replace a very old elevated infrastructure. There’s a large base cost for that that all but has to happen. The expansion, then, is incremental. I’d like to see the numbers on that. Then, there’s the options of leaving it elevated, at-grade and below grade. There are certainly technical, social and financial benefits of each.

  • FunctionForm

    When T-Rex was originally proposed, everyone knew it would not be wide enough. I remember that (I believe it was the Federal Highway Administration) recommended that I-25 should be at least 5 lanes on each side through the city and at least 6 lanes on each side through the Tech Center. They wouldn’t even provide matching federal dollars if it wasn’t at least 5 lanes through the Tech Center. Southbound I-25 south of Orchard seems to flow just fine now that the bottleneck south of C-470 was addressed SOMEWHAT. Even there, the space that could have been used for additional lanes is now occupied by the light rail. Light rail will never carry the capacity two extra freeway lanes would have carried through the same space. But when we stop creating bottlenecks, traffic flows just fine.

    How any planner thought that 4 lanes on I-25 through central Denver would ever accommodate the growth is beyond me? And there too we have wasted space on light rail at-grade. The Santa Fe interchange is a fiasco with no thought of a fix. We build bridges with support columns that won’t allow additional capacity underneath without tearing down the bridge and starting all over. It’s such a waste of tax payer money. There is not and has never been any consideration for growth in Colorado and our roads prove it.

    The City of Golden has it’s head in the sand over US 6.
    The Northwest Parkway? What is the plan to one day move millions of people through the northwest suburbs? US 6 in Golden should be a freeway, or at least have the right of way for one, that will connect with Hwy 93, then connect with the Foothills Parkway in Boulder, the Diagonal into Longmont and up 287 all the way to Fort Collins. Now did I say build it? No. I am saying plan for it. And plan for the potential of 6 lanes in each direction. Don’t create bottlenecks and then say it doesn’t work.

    Colorado has done a terrible job of building for the future. Nothing moves people where they want to go when they want to be there like the automobile. And whether cars run on fossil fuels or electricity, people will be driving cars. We need to embrace the automobile and recognize that that is how people move.

    • I-96 on the west side of Detroit was 12 lanes in 1975. The width of I-96 is significant because in 1975 Metro-Detroit’s population was 4.5 million, just about exactly what Metro-Denver’s is forecast to be in 2040.

  • It sounds to me as if the position of Streetsblog is anti-growth, as your 101 reasons not to widen freeways all point to an anti-growth position. Most induced demand is growth demand, not because the existing population drives more once congestion is reduced. The same thing could be said of Denver’s light rail, which itself has created additional outlying growth and plenty of induced demand.

    What was Cinderella City before light rail? A dead mall with no traffic and nobody living there. Now it is a TOD mixed-use development where many residents also own and drive cars. The same thing is true off several of the light rail stations along I-25. There was vacant land until the light rail stations were built which are now TOD developments where residents still own cars and drive them. If we include the park & ride locations the light rail along with I-25 widening caused induced development as far away as Castle Rock or Parker.

    I keep hearing from the anti-highway crowd about how sustainable NYC is. But wait, as NYC is several times as large as Denver in land area, not including its suburbs. From Southwest Plaza Mall to the northeast corner of DIA is 32 miles in a straight line, all of it in Denver, which is very close to the straight line distance from the south end of Staten Island to the north end of the Bronx .

    From the south end of Staten Island to outlying NYC to the northeast, say at the south end of the Throgs Neck Bridge is also 32 miles, while the distance from the northwest end of the Bronx to Coney Island is 25 miles. Do remember that west suburban NYC is in New Jersey too, while some of north suburban NYC is in Connecticut.

    In order for Denver to grow to anywhere near as large as NYC, LA, or Chicago either our suburbs must be willing to be annexed or almost all our growth except higher-density infill has to be in the suburbs. Including its Connecticut and New Jersey suburbs the Greater NYC area is roughly 60 miles by 60 miles, 3600 square miles of nothing but urban area, quite a bit of it extremely densely populated. Greater Los Angeles is actually considerably-larger than Greater NYC in land area and Greater Chicago is also quite large, much larger than Metro-Denver. Some of Greater Chicago is in Indiana too.

    Now 30 miles north of downtown Denver is east of Longmont, while 30 miles east is Bennett, 30 miles south in a straight line is almost to Larkspur, while 30 miles west in a straight line is almost to Lawson. What do you want, do you want Metro-Denver to become a big city or are you trying to keep the urban area small because you don’t like the suburbs? Whining and crying about induced demand is garbage if we are going to ever become a really big urban area. RTD is broke for the next 25 years, and the only way we can keep growing is to build new highway capacity partially funded by toll lanes. Why think small?

    I remember when some rich people commuted by helicopter to the top of the Pan Am building back in the 1960s too. Maybe that is what Denver needs, a rich man’s helicopter commuting service from downtown to Centennial, Jeffco, and DIA? Who cares if you can ride the train to DIA if you can take a helicopter there with the other rich people instead? Would you pay 10 times as much as RTD charges to fly to DIA in only 7 minutes from downtown?



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