Tab Combs @DrTCombs@transportation.social

IDK who needs to hear this but traffic lights were not invented and are rarely installed to improve safety

#TrafficLightDay

Me: Yay, I have finally found the headspace I need to work on this long overdue but really important article.

My next door neighbor: Yay, my 12,000 hp turbo wet/dry vacuum power washer with super duper sandblasting mega boost just arrived!

Also known as "that can-can" song. It was the music of choice for far too many figure skaters during the 1992 winter olympics in Albertville, France, likely trying to capture the hearts of French fans? Maybe?

You can get it stuck in your head as well:
https://www.youtube.com/watch?v=Wh5g75svRJ4

I have had *galop infernal* stuck in my head for 32 years

#ParisOlympics

Don't get me wrong -- I'm happy our state transportation agency is taking this step. It's a big change, and they should be proud to have made it happen. This is good news and, hopefully, represents the start of a much needed shift in transportation policies.

But we still have a long, long way to go before we see meaningful improvements in how we think about and provide for anyone outside a car.

#Traffic #RoadSafety #VisionZero #pedestrians #CarSupremacy (13/13)

Completely remove the possibility that a driver will have to navigate around a pedestrian who is lawfully in a crosswalk. No #RTOR, ever. No lefts--permissive or protective--across a crosswalk with an active walk signal.

Do that, and the #LPI becomes irrelevant. And walk signals will mean it's actually safe to walk.

But doing that takes willingness to prioritize #SafetyOverFlow. And we're not there yet. (12/13)

...because they had a green left arrow.

Absent other interventions, #LPIs work best when:
1. pedestrians are fit, attentive, and ready to bolt when they walk signal comes on, and
2. right-turning drivers come to a full stop and look both ways before turning right, and
3. left-turning drivers are capable of managing an intense cognitive load and valuing the safety of others as much as their own

which is to say, very rarely.

What works is fully protected walk phases. (11/13)

And that pedestrian is now in a stand-off with a driver who's just been told that this is their special time to go, and no one is supposed to be in their way. At best, they see the pedestrian and honk, yell, generally get pissy about it, but at least they probably don't hit them.

At worst, they don't see the pedestrian at all because the green arrow told them they didn't even have to look. And they are totally baffled to discover that they just hit someone and it was their own fault... (10/13)

...we're happy to give our overworked brains a moment's rest, and let the signal do the thinking. Yeah, sure, the law says we also have to be paying attention to our surroundings, but turning left is hard and our brains are tired. The light says we can go, so we can go.

Except sometimes there's also a light telling a pedestrian they can go. (9/13)

If permissive lefts aren't bad enough, some intersections actually give left turning motorists protective lefts--green left arrows--when there's an active walk sign in the path of the left turning motorist. IMHO, this is even worse. Here's why:

A green left arrow evokes a sense of priority and privilege among drivers. "This is my special green arrow. Nobody can stop me now."

But driving is hard and most drivers are really bad at it. So when we get a special signal just for us... (8/13)

If said pedestrians are speedy, the LPI may give them enough of a head start to get out of the way of potential left turners. But not all pedestrians are athletes. Just like drivers, many pedestrians are old, young, creaky, carrying heavy stuff, and/or distracted. Five seconds is not enough for them to get to safety, especially when there are multiple lanes to cross. (7/13)

Trouble is, driving is hard and most drivers are really bad at it, and the cognitive burden of identifying a safe gap in multiple lanes of on-coming traffic is pretty heavy, and our real, rational fear of getting clobbered by other vehicles makes us forget we also need to be looking to make sure we don't clobber any pedestrians...pedestrians who are lawfully in the crosswalk on the far side of the intersection. (6/13)

The other issue is that it's also common in the US to allow drivers to turn left across crosswalks with active walk signals. Sometimes we do this with a permissive left, which is a flashing yellow arrow that says to drivers, "it's up to you."
Permissive lefts are typically used on multi-lane roads. Drivers who wish to turn left must identify a safe gap in on-coming traffic, and when they see one they think they can fit through, they can go for it. (5/13)

The LPI does nothing in this situation, because allowing right turns on red (#RTOR) negates the head start. Banning RTOR is the only way to ensure that pedestrians get to take full advantage of the LPI.

Some cities have tried selectively prohibiting RTOR at intersections with known safety issues. It's a good start, but compliance tends to be poor because humans don't like following conditional rules. It's going to take full scale ban to change driver behaviors. All or nothing. (4/13)

Across most of the US, it's legal for drivers to turn right on red, even when that means crossing a crosswalk with an active 'walk' signal. In theory, you are supposed to check for pedestrians...

...but driving is hard, and in reality most drivers are really bad at it, and they don't look to their right before turning right, which means they don't see the pedestrian lawfully in the crosswalk before hitting them. (3/13)

LPIs improve intersection safety much the same way large print menus improve eyesight. Which is to say they are useful and better than nothing. But they do nothing to address the underlying issue.

The underlying issue is, at most signalized intersections in the US, a 'walk' signal does not mean it's safe to walk across the intersection. It means that if you get hit while you are walking across the intersection, it's legally not your fault (presuming your body lands in the crosswalk). (2/13)

A new policy to add leading pedestrian intervals (LPIs) is a step in the right direction by NCDOT. This signal timing gives pedestrians a head start into crosswalks, making them more visible to motorists who wish to turn across the pedestrian's path. The walk signal turns on ~5 seconds before the parallel traffic light turns green.
But it's a partial solution to a symptom of a much greater problem. 🧵
https://www.ncdot.gov/news/press-releases/Pages/2024/2024-07-26-pedestrian-safety-crosswalks.aspx