Salt Lake lowers speed limit to 20 mph for most streets

Started by elsmere241, May 12, 2022, 11:30:16 AM

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elsmere241

https://ksltv.com/492573/salt-lake-city-council-lowers-speed-limit-on-most-streets-to-20-mph

Elsmere, DE, where I used to live, has this as well.  I see it as a good reminder to slow down.


Max Rockatansky

What's the difference between getting run over at 20 MPH as opposed to 25 MPH?  I ask this seriously because I was run over (launched more accurately) as a pedestrian once when I was running.  Is there actual data to suggest that there is a substantial difference in pedestrian accidents between 20-25 MPH?

triplemultiplex

Eh, I think it's more about being able to stop faster than it is how hard someone gets run over.
But it really doesn't matter unless the fuzz is out there enforcing that SL.

If they want people to go slower on neighborhood streets in SLC, build them narrower.  City streets in Utah are way, way too wide.
"That's just like... your opinion, man."

Max Rockatansky

Quote from: triplemultiplex on May 12, 2022, 04:42:40 PM
Eh, I think it's more about being able to stop faster than it is how hard someone gets run over.
But it really doesn't matter unless the fuzz is out there enforcing that SL.

If they want people to go slower on neighborhood streets in SLC, build them narrower.  City streets in Utah are way, way too wide.

Even then, how big of a real world difference is that stopping time at 20 MPH versus 25 MPH?  It's not there are cars out there now rocking a set of four drum brakes.

7/8

Quote from: Max Rockatansky on May 12, 2022, 11:54:21 AM
What's the difference between getting run over at 20 MPH as opposed to 25 MPH?  I ask this seriously because I was run over (launched more accurately) as a pedestrian once when I was running.  Is there actual data to suggest that there is a substantial difference in pedestrian accidents between 20-25 MPH?

I found an article with an interactive graph showing % chance of pedestrian death by speed split into age groups. Unfortunately the interactive percentages don't seem to work for me, but it looks like roughly 30-50% greater chance of death at 25 vs. 20 mph.
https://www.propublica.org/article/unsafe-at-many-speeds

Quote from: triplemultiplex on May 12, 2022, 04:42:40 PM
If they want people to go slower on neighborhood streets in SLC, build them narrower.  City streets in Utah are way, way too wide.

For sure, a speed limit decrease with no change in road geometry unfortunately won't be effective.

SectorZ


SkyPesos

I rather have the speed limits set by the physical features on and surrounding a road, than an artificial number. If they want people to drive slower, narrow the street, add trees, add speed bumps, etc.

Max Rockatansky

Quote from: SkyPesos on May 12, 2022, 06:15:54 PM
I rather have the speed limits set by the physical features on and surrounding a road, than an artificial number. If they want people to drive slower, narrow the street, add trees, add speed bumps, etc.

Problem is that redesigning roads costs money as does enforcement.  Given how slap-bang blanket approach at hand I suspect this will be a pretty toothless policy with lax enforcement. 

kalvado

Difference between 20 and 25 is in stopping distance I would think. So lower speed should mean higher chance to stop before making contact with a pedestrian.
There is also a reduction of higher fine threshold (speed limit + 10, 20 or 30, or whatever they use) which is good for budget. I don't know if this would really reduce accident rates.
I wonder which streets would be affected. I would be more or less OK if this affected a last half a mile of my commute, maybe last mile, and cover mostly stop sign controlled area.


vdeane

I'd wager that it's the chance of severe injury/death at a given speed, not stopping distance.  Having been to many planning conferences and working groups, the former is what they talk about all the time with respect to vehicle speed, not the latter.  The Streetsblog article below sums it up nicely... stopping distance is mentioned, but it's practically a footnote while the article focuses on chance of severe injury/death.

https://usa.streetsblog.org/2016/05/31/3-graphs-that-explain-why-20-mph-should-be-the-limit-on-city-streets/
Please note: All comments here represent my own personal opinion and do not reflect the official position of NYSDOT or its affiliates.

kalvado

Quote from: vdeane on May 12, 2022, 10:07:01 PM
I'd wager that it's the chance of severe injury/death at a given speed, not stopping distance.  Having been to many planning conferences and working groups, the former is what they talk about all the time with respect to vehicle speed, not the latter.  The Streetsblog article below sums it up nicely... stopping distance is mentioned, but it's practically a footnote while the article focuses on chance of severe injury/death.

https://usa.streetsblog.org/2016/05/31/3-graphs-that-explain-why-20-mph-should-be-the-limit-on-city-streets/
Survivor bias at it's best

allniter89

Quote from: Max Rockatansky on May 12, 2022, 06:21:34 PM
Quote from: SkyPesos on May 12, 2022, 06:15:54 PM
I rather have the speed limits set by the physical features on and surrounding a road, than an artificial number. If they want people to drive slower, narrow the street, add trees, add speed bumps, etc.
How would adding trees slow people down?

Problem is that redesigning roads costs money as does enforcement.  Given how slap-bang blanket approach at hand I suspect this will be a pretty toothless policy with lax enforcement. 
BUY AMERICAN MADE.
SPEED SAFELY.

kphoger

Quote from: allniter89 on May 12, 2022, 11:38:09 PM
Quote from: Max Rockatansky on May 12, 2022, 06:21:34 PM
Quote from: SkyPesos on May 12, 2022, 06:15:54 PM
I rather have the speed limits set by the physical features on and surrounding a road, than an artificial number. If they want people to drive slower, narrow the street, add trees, add speed bumps, etc.
How would adding trees slow people down?

Problem is that redesigning roads costs money as does enforcement.  Given how slap-bang blanket approach at hand I suspect this will be a pretty toothless policy with lax enforcement. 

Preview, people.  Preview.

↓  Fixed below  ↓

Quote from: allniter89 on May 12, 2022, 11:38:09 PM

Quote from: Max Rockatansky on May 12, 2022, 06:21:34 PM

Quote from: SkyPesos on May 12, 2022, 06:15:54 PM
I rather have the speed limits set by the physical features on and surrounding a road, than an artificial number. If they want people to drive slower, narrow the street, add trees, add speed bumps, etc.

Problem is that redesigning roads costs money as does enforcement.  Given how slap-bang blanket approach at hand I suspect this will be a pretty toothless policy with lax enforcement. 

How would adding trees slow people down?
Keep right except to pass.  Yes.  You.
Visit scenic Orleans County, NY!
Male pronouns, please.

Quote from: Philip K. DickIf you can control the meaning of words, you can control the people who must use them.

jakeroot

Street trees create a visually narrower path and reduce horizontal visibility, causing most people to drive a bit slower to account not being able to see as well. Same reason you might not fly down a neighborhood street with parked cars along both edges (especially two-way, one-lane streets like here in the Seattle area).

--

From what I've seen, while there is very little enforcement with 20 limits, there is a small decrease in vehicle speeds from whatever the previous average speed was. It has long been argued that drivers simply ignore speed limit signs and drive whatever speed they feel is safe. While that is sometimes true, I don't think it's true for all streets. The average speeds may drop from 29 to 26, but that is still good in terms of pedestrian survivability.

hotdogPi

Blanket 20 zones desensitize drivers to roads that actually need to be 20, such as this, which has a dangerous intersection just out of view (move forward and you'll see it):

https://www.google.com/maps/@42.7268168,-71.1570436,3a,75y,278.74h,86.18t/data=!3m6!1e1!3m4!1sxOCF9a6VEL5B-XYjGhMJQw!2e0!7i16384!8i8192
Clinched, minus I-93 (I'm missing a few miles and my file is incorrect)

Traveled, plus US 13, 44, and 50, and several state routes

I will be in Burlington VT for the eclipse.

jakeroot

Quote from: 1 on May 13, 2022, 11:49:29 AM
Blanket 20 zones desensitize drivers to roads that actually need to be 20, such as this, which has a dangerous intersection just out of view (move forward and you'll see it):

https://www.google.com/maps/@42.7268168,-71.1570436,3a,75y,278.74h,86.18t/data=!3m6!1e1!3m4!1sxOCF9a6VEL5B-XYjGhMJQw!2e0!7i16384!8i8192

They are not actually blanket 20 limits. They are usually just non arterials. Here in Seattle, all streets are 20 except arterials and those posted otherwise (usually 25 to 45). An arterial posted at 20, at least around here, would either mean a very dangerous, curvy road, or a school zone (yes, school zones and neighborhood streets have the same default limit).

Max Rockatansky

#16
Quote from: kalvado on May 12, 2022, 10:16:34 PM
Quote from: vdeane on May 12, 2022, 10:07:01 PM
I'd wager that it's the chance of severe injury/death at a given speed, not stopping distance.  Having been to many planning conferences and working groups, the former is what they talk about all the time with respect to vehicle speed, not the latter.  The Streetsblog article below sums it up nicely... stopping distance is mentioned, but it's practically a footnote while the article focuses on chance of severe injury/death.

https://usa.streetsblog.org/2016/05/31/3-graphs-that-explain-why-20-mph-should-be-the-limit-on-city-streets/
Survivor bias at it's best

I guess that I was part of the 4 of 5 that survived the 30 MPH mark they cited.  When I was hit by a car in 2010 (crossing C Avenue in Coronado along the side of the northbound lanes of CA 75) I had the right of way and the driver who hit me didn't stop at a stop sign.  All the same, I would be fooling myself if I didn't own up to the fact that I shouldn't have trusted/assumed someone would have stopped on a busy highway like CA 75.   The one way streets orientation of CA 75 coming/going from the Coronado Bridge is too much for a driver not to have been tempted to run a stop sign when they saw a clearing in the three lanes of traffic going to San Diego.  Had I been presented with the same circumstance I would have gone down C Avenue to cross at a less busy spot. 

I definitely do take a far more defensive mindset while running or cycling since that accident, too bad it had to be a serious one for me to do it.  There is so much emphasis on defensive driving, but where is that mindset for pedestrians?  I don't know, a blanket speed limit change for 25 MPH zones seems like an overreach for things that possibly could possibly resolved by redesigning certain affected roads.  Of course that requires things like money be spent on planning, design and potential construction.



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