Technology

38451 readers

84 users here now

A nice place to discuss rumors, happenings, innovations, and challenges in the technology sphere. We also welcome discussions on the intersections of technology and society. If it’s technological news or discussion of technology, it probably belongs here.

Remember the overriding ethos on Beehaw: Be(e) Nice. Each user you encounter here is a person, and should be treated with kindness (even if they’re wrong, or use a Linux distro you don’t like). Personal attacks will not be tolerated.

Subcommunities on Beehaw:

This community's icon was made by Aaron Schneider, under the CC-BY-NC-SA 4.0 license.

founded 3 years ago

MODERATORS

TheRtRevKaiser@kbin.social

Like to drive fast? Virginia has an anti-speeding device for you. (www.washingtonpost.com)

submitted 6 days ago by misk@sopuli.xyz to c/technology

6 comments fedilink hide all child comments

Archive: https://archive.is/2025.03.27-121252/https://www.washingtonpost.com/dc-md-va/2025/03/27/virginia-speed-limit-device/

Virginia is set to become the first state in the country to require some reckless drivers to put devices on their cars that make it impossible to drive too fast.

D.C. passed similar legislation last year. Several other states, including Maryland, are considering joining them. It’s an embrace of a technological solution to a national problem: Speeding contributes to more than 10,000 deaths a year.

Under the Virginia legislation, a judge can decide to order drivers to install the speed limiters in their vehicles in lieu of taking away their driving privileges or sending them to jail. It takes effect in July 2026.

Del. Patrick A. Hope (D-Arlington) said various advocacy groups, including Mothers Against Drunk Driving and the National Safety Council, gave him the idea. He drove a car outfitted with the technology and was impressed. “It was easy to use, and once you’re engaged it’s impossible to go over the speed limit,” he said. “It will make our streets safer.”

you are viewing a single comment's thread
view the rest of the comments

[–] alyaza 6 points 6 days ago* (last edited 6 days ago) (1 children)

Then we slap a random-ass speed limit sign down and say “job’s done.”

we don't actually--the basis we derive most speed limits from is actually much worse, if you can believe that. from Killed by a Traffic Engineer:

Traffic engineers use what we call the 85th percentile speed. The 85th percentile speed is whatever speed 85 percent of drivers are traveling slower than. If we have 100 drivers on the road and rank them in order from fastest to slowest, the 15th fastest driver would give us our 85th percentile speed.

Traffic engineers will then look 5 mph faster and 5 mph slower to see what percentage of drivers fall into different 10 mph ranges. According to David Solomon and his curves, the magnitude of the speed range doesn’t matter as long as we get as many drivers as possible into that 10 mph range.

and, as applied to the example of the Legacy Parkway, to show how this invariably spirals out of control:

North of Salt Lake City, the Legacy Parkway parallels Interstate 15 up to the Wasatch Weave interchange where these highways come together. It’s a four-lane, controlled-access highway with a wide, grassy median and more than its fair share of safety problems.

So how did the Utah Department of Transportation (UDOT) respond?

It increased the speed limit from 55 mph to 65 mph. It said the speed limit jump will “eliminate the safety risk” on the Legacy Parkway.

UDOT conducted speed studies up and down the Legacy Parkway. It found that most drivers were going much faster than the 55 mph speed limit. Channeling the ghost of traffic engineers past, the safety director for UDOT said, “We decided to raise the speed limit to a speed that is closer to what drivers are actually driving. In doing so, we hope to eliminate the safety risk of speed discrepancy, which can happen when you have a significant difference between the speed most drivers are actually traveling and those who are driving the posted speed limit.”

In the case of the Legacy Parkway, the 85th percentile speeds ranged from 65 mph to 75 mph. Based on that and what it deems engineering judgment, UDOT originally proposed raising the speed limit to 70 mph. After community pushback, it settled for 65 mph.

According to the Manual on Uniform Traffic Control Devices (MUTCD), this slight adjustment is acceptable. The MUTCD specifies that speed limits “should be within 5 mph of the 85th percentile speed of free-flowing traffic.”

[–] SteevyT 1 points 6 days ago* (last edited 6 days ago)

Honestly, the 85 percentile rule, when actually used, is about the same as RNG, but with a bias for higher. Iforget where I saw it, but from what I remember seeing even the 85% rule gets deemed as too resource intensive so a speed limit from a "similar" (for some random definition of similar) road's speed limit is used.

I feel like it was something in the vein of a Strongtowns or Climate Town video.

Edit: Which now that I think about it, I'm reasonably sure the video also referenced the MUTCD.