Why Does Downtown Denver Have Street Corners That Drivers Can Roll Right Over?

Cutting it close at one of the city's "depressed corners." Photo: David Sachs
Cutting it close at one of the city's "depressed corners." Photo: David Sachs

A few readers have asked us about the wide, sweeping street corners that blend seamlessly into the asphalt at many downtown intersections.

A Denver Public Works spokesperson says the corners are 30-year-old relics of a previous approach to pedestrian crossings. The intersections used to have “Barnes Dance” signals, which stop all car traffic to give people on foot or in wheelchairs an exclusive phase. People could cross in any direction, and the wide ramps with a subtle slope — called “blended transitions” or “depressed corners” — opened up all possible paths between different corners.

Some intersections still have exclusive pedestrian phases, but in 2011 the city made it illegal to cross diagonally during them. The depressed corners remain in place even though they no longer serve a discernible purpose.

These street corners put pedestrians at risk in another way too. According to the National Association of City Transportation Officials, drivers are more likely to make turns at dangerously high speeds at corners with large turning radii, and curb radius longer than 15 feet is not recommended. Most of these downtown corners have a curb radius of 25 feet.

And without a curb, drivers can roll right over them.

“Designing Sidewalks and Trails for Access,” an engineering guide sponsored by the Federal Highway Administration, found “very significant drawbacks to the use of depressed corners by pedestrians.”

Specifically, the manual says, this form of curb ramp enables drivers of cars and large trucks to travel into the pedestrian zone when taking right turns and “encourages” drivers to speed around corners, heightening the likelihood of injury or death.

DPW's new curb ramps look like this one on 19th and Logan — a sharper angle and a heightened curb that drivers won't run over. Image: Google Maps
DPW’s new curb ramps look like this one on 19th and Logan — a sharper angle and a heightened curb that drivers won’t run over. Image: Google Maps
Photo: David Sachs
Without a curb, nothing’s stopping drivers from rolling over the pedestrian zone. Photo: David Sachs

That’s no good, especially for crowded downtown streets. On 15th Street between Cleveland Place and Little Raven Street, a segment larded with depressed corners, drivers hit 22 people between 2012 and 2015, according to city crash data.

DPW doesn’t have any plans to retrofit these things, though. In fact, a spokesperson said even if the city adds a curb, the radii would stay the same to accommodate trucks. But NACTO says “a large corner radius should not be used to facilitate a truck turning from the right lane into the right lane.”

Fixing these dangerous conditions doesn’t require the time and expense of digging up the street. NACTO recommends using planters or plastic posts (think Colfax and Park) to tighten corners and make drivers take turns more carefully.

  • David B

    I still miss the Barnes dance (and often cross diagonally when the light timing permits, as do many other folks who’ve also worked downtown for decades). However, curbs and bump outs would be really nice. In addition to the pedestrian risk, cyclists also lose out.
    The current design encourages drivers to use bike lanes as a turn lane, as there is enough space to squeeze in. The corner of 18th and Wazee is particularly bad for this (though the huge trash skip parked there for a month has prevented it recently–as soon as that is gone, the bike lane will be in peril again).

    • surly trucker

      I miss the barn dance too! Peds deserve their own crossing phase – without being forced to compete with turning vehicles.

      • Amerisod

        Why did they eliminate these and is there a chance they will come back? People in many cities push for a pedestrian crossing phases. They are so much safer and more comfortable. I’m sorry to see Denver backsliding on this.

        • David B

          There’s some hand-waving explanations here that I’m not sure I entirely buy:
          https://www.denverpost.com/2011/04/05/denver-to-eliminate-diagonal-crossings-at-intersections/
          I would guess it was mostly motivated by moving cars faster. It does seem like going in the opposite direction a downtown area should be going.

          • Amerisod

            Interesting. They are increasing the time for the light cycle by 15 seconds, but figure that people can go only 3.5 fps.

            So, 75 seconds times 4 fps is 300 ft. And 90 seconds times 3.5 fps is 315 ft. People can travel farther with the new times, even though they might walk more slowly. I don’t see their reasoning, but then again, I am using scratch paper and they have “high powered computers.”

            But I’d better stop before I get fined for practicing engineering without a license like that dude who questioned traffic lights in Oregon.

  • David B

    Since reading this article, I’ve noticed more of those wide, curbless corners, some fairly new, well outside of downtown, so I call shenanigans on “30-year old relics.” Take a look at the NE corner of 38th and Sheridan, 4 miles from downtown, where there has never been a diagonal crossing–that curbless corner was installed last year. I’m reasonably sure that one is expressly designed for vehicle turns (admittedly, it was tricky–but entirely possible when there was a curb). If you look at that particular corner in streetview, you can see clear tire tracks on the entire sidewalk–don’t stand on that corner if you value your life. In fact, the only curb there is a bumpout that appears to be designed to protect the signal pole (and it has obvious tire marks on it too):
    https://www.google.com/maps/@39.7694178,-105.0531805,3a,60y,47.25h,62.03t/data=!3m6!1e1!3m4!1sKYDxRwYn0hTUoQCGDiNfCw!2e0!7i16384!8i8192

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