A national investigation on the impacts of lane width on traffic safety

Johns Hopkins finds narrower lanes can make roads safer.

And you think I will read 129 pages! Thinking these are chalk marks for cyclists. Google Maps

You can read the executive summary. It’s been reported in the news. I thought I’d cite the source.

Wow that is a long straight flat road… lol

The conclusions in the summary seem reasonable. Low speed limit city streets should not have wide lanes.

My preference for safer roads would be revival of 55mph speed limit. I’m sick to death of these 85mph+ menaces.
There is no hurry.

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I guess it depends on where you live. Except on some interstate highways, the speed limit on limited access highways is 55mph in Maryland. It doesn’t matter because a lot of drivers go 70+ anyway. Anyway, the article doesn’t address limited access highway issues. It discusses how to make city streets with much mower speed limits safer.

Nashville speed limit is less in the city, but once you get out to more open road with much less need to be shifting lanes for exits the speed limit goes to 70 mph, but in downtown Nashville it is 55 mph…
And they lowered it back to 65 year ago, didn’t last and back to 70mph where it needs to be…

There might be a more flexible and creative way to implement this.

First of all, the speed limit actually needs to be enforced. Changing speed limits won’t work if we’re letting people drive 65 to 70 on a regular basis with minimal risk of getting a ticket.

There could be a left lane and a right lane speed limit. The right lane would have a lower speed limit to make entrance ramps safer. There could be a right lane speed limit zone for sections of highway that have entrance ramps.

There could be a increased speed limit for times with less traffic. If a driver is able to maintain at least 3 seconds of following distance from the car in front, they will be able to go 10 MPH faster, or 70 MPH. If not, then will be forced to obey the posted speed limit of 60 MPH. When it is raining the 60 MPH limit would be in effect for everyone.

That would be a really hard sell in the areas that now have a 75mph or 80mph speed limit.

My work recently brought me to SoCal for a week, and every time I’m down there it takes me a day or 2 to remember to drive faster. I was on a nice city street, 3 lanes each direction. Speed limit was 40, I was in the middle lane doing 50, and I constantly had people going around me–even the cop who passed me on the right.

You should drive across Texas, Kansas, Montana, or Nevada… and then see if you have the same opinion.


I think the people who did the study did not consider tractor trailers and RVs
they are legally allowed to be 8" 6" in width PLUS the width of the mirrors. That puts them over 9’ in width not even considering that not every tractor trailer is in perfect alignment. Any dog tracking increases effective width. I drove some tractors that had no provisions for adjusting the alignment of the drive wheel axle(s). Wherever the holes were drilled in the frame for the spring mounts determined the alignment.


Actually, they didn’t have to since the study deals with city and suburban streets, not major thoroughfares. If you read the summary, on page 4 near the bottom the last 4 bullet points state that narrower lanes are only appropriate for speed limits under 35 mph. They also say that major roads have to be 11 ft wide or wider to accommodate the wide loads you mention.

Trucvs navigate all residential roads even if not on truck routes when making home deliveries as do moving trycks. People also drive their RBs from home Trucks and RVs are still over9 " with the ,irrors eve when going 35 or 25/


Good news; The right lane exists.


Round abouts are all the rage in Minnesota now. Maybe because it’s easier to spend a lot of highway money on them. At any rate the latest one is on the edge of town so you go from 60, to 40 for a short while, then down to 20 for the roundabout then up to 40, then 30 or 45 depending on which route you take. Makes you head spin.

There are no lane markers on our residential roads. I suppose you could say that the lanes are 25 ft wide. They are effectively much narrower of course because people park on both sides of the road. Big trucks can get through and they travel way under the 25 mph limit.

Yeah and as the speed demons pass me on the left, sometimes their frustrated fellows feel forced to tail me NASCAR style for a few minutes with their middle fingers up.
I figured out there was no hurry while still in my 20s.
Slow learners amuse me.

I think roundabouts make far more sense than the old stop&go.

A Dutch traffic engineer, working on the hypothesis that making people pay attention makes roads safer and faster than telling them what to do, studied roundabouts (it’s a kiddie term, but it isn’t the same as a traffic circle, the phrase I prefer) and found they made intersections safer and faster.

We have a bunch in Albuquerque, new over the last 10 years or so, that some resent. They’re on slower roads, not like the one on the edge of @bing’s town, probably work, because Albuquerqueños are notorious breakers of rules. They can ignore a stop sign much more easily than a roundabout. Making them slow down and pay attention makes intersections safer than stop signs.

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