Preventing Bicycle Fatalities at US-36 and Violet

Partial repost with permission from Flatironbike.com. Please go there to read the full article

Two bicyclists have been killed at the intersection of US-36 and Violet Avenue since 2009. The most recent was TJ Doherty, on July 24th, 2012. Both cyclists were headed southeast on US-36, and were hit by cars traveling northwest, making left turns onto Violet. In this area US-36 is just outside of Boulder’s city limits, in the county, but it’s the Colorado Dept. of Transportation (CDOT) that’s responsible for it. Looking at the aerial view below we can explore why this intersection might be particularly dangerous for cyclists.

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Northwest bound vehicles on US-36 have a dedicated left turn lane, and no obligation to stop before making their turn. The angle that Violet Ave. makes with the highway is quite oblique, meaning that it can be taken at high speed, and because US-36 has a speed limit of 55 mph in this area, cars often will take it at high speed if they don’t see any oncoming traffic.

From a southeast bound bicycle’s point of view, there’s no obviously correct place to be on the road, if they’re planning to proceed through the intersection. The shoulder on the west side of the road narrows to a few inches, and it’s to the right of a right-turn-only lane. If you ride all the way to the right, you risk a vehicle turning in front of you onto Violet. Your intent to continue through the intersection is also unclear to oncoming traffic. Most cyclists instead take a position that’s well within the right turn lane, to prevent right-turning vehicles from passing them and immediately turning right in front of them. However, this lane position still leaves their intent ambiguous to oncoming traffic. Alternatively, you might choose to straddle the line separating the through travel lane and the right turn lane. This makes the bike relatively visible, and more clearly conveys the intent to continue through the intersection, at the expense of potentially sandwiching the cyclist between right turning vehicles and very fast moving through traffic. If the cyclist instead chooses to behave exactly like a motor vehicle, moving into the through lane of traffic, the very large difference in speed between the bike and the other vehicles in that lane creates a hazard. Thus, there’s no right place for a cyclist to be on this road if they’re planning to continue through the intersection.

When we combine the unavoidable ambiguity of the through cyclist’s intent with the very high left-turning speeds of oncoming traffic, we have a recipe for disaster. A recipe which has killed two people in three years.

Read all of the in depth article at Flatironbike.com.

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4 Comments

violet

Also it is slightly down hill for the cyclist so they are going pretty fast as well. I almost got hit by a car there for all of the above reasons. The turning car was going fast to make the turn before another oncoming car got there and I was going pretty fast SE on 36. I got lucky and the drive just saw me and hit the brakes so I slid by the front bumper with a couple inches to spare. Once I saw he was going for the turn it was too late for me to slow down, because he was going about 55 and I was doing about 35, on a TT bike in the aerobars. I learned that day to not ride in the aerobars anywhere around town, even there, which is pretty wide open. You can't get to your brakes fast enough.

Anyway the point is...they are going fast and they can miss judge the speed of the cyclist, even if they see the cyclist (which sometimes they don't) And by they, I mean we, because we all drive cars as well, but I'd like to think we are all especially aware of cyclist since we are cyclist.

I don't think cyclist

I don't think cyclist placement is so ambiguous at this intersection. While being aware of traffic behind me, I ALWAYS ride through the intersection (SE on 36) in the lane closest to the middle -- either positioned on the white line or a little to the left of it (so the white line between the through lane of traffic and the right turn lane). Like someone already noted -- speeds are high there for cyclists, so I feel more secure riding in the direct lane of traffic...

That intersection is

That intersection is butt-clencher for sure. Also saw a cyclist being carted off on a stretcher this morning just east of baseline and 76th. People pull out of the side roads into the bike lane to see the road, but don't check the bike lane first.