"Improvements" that made things worse

[ran4sh]

As for roundabouts, they make things worse when they are placed on high-speed roads. I know of one that GDOT placed at the intersection of 2 state routes that each have a 55 mph speed limit.

[kphoger]

As for roundabouts, they make things worse when they are placed on high-speed roads. I know of one that GDOT placed at the intersection of 2 state routes that each have a 55 mph speed limit.

The alternatives are often (1) two-way stop control, which leads to a higher incidence of fatal side-impact crashes, or (2) a stoplight, which has similar downsides on a high-speed road as a roundabout has.

This roundabout at an intersection of two 65-mph highways, for example, used to be the site of a lot of really bad accidents.  Now it isn't.

[webny99]

This roundabout at an intersection of two 65-mph highways, for example, used to be the site of a lot of really bad accidents.  Now it isn't.

I am obligated to point out that one of the approaches is actually 30 mph. (Of course, that doesn't mean your statement is untrue, but it is relevant context.)

[index]

The I-77 toll lanes in the Charlotte Area.

Discussion on this in the Charlotte thread for context/explanation: https://www.aaroads.com/forum/index.php?topic=16665.msg2613433#msg2613433

[jmacswimmer]

I-95 widening between the Capital Beltway (I-495) and the Occoquan River from 6 to 8 lanes. I'm not opposed to concept of widening, but the location they chose to put the 4th lane drop just south of the river has done nothing but create a chokepoint that is there over half the day, and starts around noon and lasts until well after rush hour. And extends for miles north.

This was the exact example I thought of the instant I saw this thread...4th lane drops instantly beyond a 5th auxiliary lane departing for VA 123, then followed immediately by 2 onramps.  Literally anywhere would have been a better location to drop the 4th lane

Another nearby example that comes to mind is the part-time left shoulder lane on I-495 north between the HOT-lane terminus & the Legion Bridge...all it did was push one bottleneck all the way to the foot of the Legion Bridge, which already had a bottleneck from the GW Parkway onramp.  (The consolation is that this was always intended as a stopgap measure, with VDOT's 495 NEXT & MDOT's 270/495 P3 Program on the horizon).

[sprjus4]

I-95 widening between the Capital Beltway (I-495) and the Occoquan River from 6 to 8 lanes. I'm not opposed to concept of widening, but the location they chose to put the 4th lane drop just south of the river has done nothing but create a chokepoint that is there over half the day, and starts around noon and lasts until well after rush hour. And extends for miles north.

This was the exact example I thought of the instant I saw this thread...4th lane drops instantly beyond a 5th auxiliary lane departing for VA 123, then followed immediately by 2 onramps.  Literally anywhere would have been a better location to drop the 4th lane

They're currently building an auxiliary lane between the VA-123 on ramp southbound to connect to the VA-294 ramp, but I question how effective it will be. It's not going to eliminate the worse backup which is that 4th lane drop. They need to extend that to be the auxiliary lane. That would at least help more.

[kphoger]

This roundabout at an intersection of two 65-mph highways, for example, used to be the site of a lot of really bad accidents.  Now it isn't.

I am obligated to point out that one of the approaches is actually 30 mph. (Of course, that doesn't mean your statement is untrue, but it is relevant context.)

The least-trafficked leg of the roundabout, yes.  (It actually has a 20mph advisory in the other direction.)

[MCRoads]

(cue the few users on here that think multi-lane permissive left turns should be allowed).

And do exist in some states.

Colorado. Soo many in the springs. And to be honest, they work pretty well.

[hbelkins]

Roundabouts are typically touted as safety improvements. I'm hard-pressed to think of examples where they have been sold as traffic improvements.

[kphoger]

Roundabouts are typically touted as safety improvements.

Yep.  And I cited an example that was a success:

As for roundabouts, they make things worse when they are placed on high-speed roads. I know of one that GDOT placed at the intersection of 2 state routes that each have a 55 mph speed limit.

The alternatives are often (1) two-way stop control, which leads to a higher incidence of fatal side-impact crashes, or (2) a stoplight, which has similar downsides on a high-speed road as a roundabout has.

This roundabout at an intersection of two 65-mph highways, for example, used to be the site of a lot of really bad accidents.  Now it isn't.

[texaskdog]

Building a roundabout in (insert name of any location where a roundabout has been built.)

You're saying that every single roundabout project made things worse?

Here's a scorching take:

Every single roundabout that replaced a traffic signal made things worse.
Every single roundabout that replaced a stop sign made things better.

Idiots here built a roundabout which was completed before we moved in.  They didn't do it right so they had to close it again.  It adds 5 miles to the drive to get out of our neighborhood because they didn't build an adequate detour.  I can't wait to vote city council out for that mess.

[Scott5114]

Replacing button copy and demountable copy with direct-applied computer-cut sheeting has resulted in cheaper and more reflective signs, but made design quality worse by making it easy to distort and compress text, use unapproved typefaces, and the like.

[Bruce]

The SR 99 tunnel in downtown Seattle did nothing to help traffic and only pushed traffic onto city streets. A lot of waste that could have gone towards the Surface + Transit option to actually provide a decent alternative.

[sprjus4]

The SR 99 tunnel in downtown Seattle did nothing to help traffic and only pushed traffic onto city streets. A lot of waste that could have gone towards the Surface + Transit option to actually provide a decent alternative.

And not building the tunnel would've just dumped traffic onto city streets even more... 

[kphoger]

Replacing button copy and demountable copy with direct-applied computer-cut sheeting has resulted in cheaper and more reflective signs, but made design quality worse by making it easy to distort and compress text, use unapproved typefaces, and the like.

One might see that as a net gain rather than a net loss.

[Konza]

The solution to the "Hillside Strangler" on I-290 in the near west Chicago duburbs did little more than push the problem east.

[ran4sh]

As for roundabouts, they make things worse when they are placed on high-speed roads. I know of one that GDOT placed at the intersection of 2 state routes that each have a 55 mph speed limit.

The alternatives are often (1) two-way stop control, which leads to a higher incidence of fatal side-impact crashes, or (2) a stoplight, which has similar downsides on a high-speed road as a roundabout has.

This roundabout at an intersection of two 65-mph highways, for example, used to be the site of a lot of really bad accidents.  Now it isn't.

Stoplights with sufficient advance warning should be fine. And by advance warning I mean, for example, a warning sign with flashing lights, where the lights turn off if the light is green and traffic is moving at free-flow conditions. The point is to give the driver a specific warning of whether they will have to slow down or not (which is especially important for trucks).

[kphoger]

But a stoplight isn't what was there before.  It was just a two-way stop.  Either one might have been an improvement.  All I'm saying is that the roundabout was an improvement–not that a stoplight necessarily wouldn't have been.

[sprjus4]

^ Grade separation 

[sparker]

^ Grade separation 

Yep!  Some areas just won't be improved -- efficiency or safety-wise without them.  The junction of CA 12 and CA 113 west of Rio Vista is a prime example -- bad lines of sight, so they plowed up the hillside and installed a roundabout on one of the major commercial/recreational arteries between I-5 and the North Bay/wine country.  It's also tule fog country; a couple of months after installation, an elderly couple fatally plowed into the structures in the center of the circle.  A few posts upthread, a suggestion was made for a signal with ample advance notice via flashing overhead text (successfully used on CA expressways for decades); that would have been much more appropriate here than something that posed an physical obstacle on a 55mph facility with regular 20-30% speed overages.  But a simple "super-2" grade separation with diamond ramps would have been the best solution -- if Caltrans weren't presently allergic to anything that vaguely resembles new freeway construction -- and seemingly obsessed with aggregate speed reduction, regardless of facility type.  This certainly was an ill-conceived "improvement" that was in fact a regression!   

[epzik8]

When MD 24 opened between US 1 and I-95 in 1987, it was supposed to alleviate congestion on the old MD 24 corridor (which became MD 924) and provide an uninterrupted trip between the immediate Bel Air area and I-95. There were only two traffic signals at the time of its opening: at Boulton Street and just down the road at US 1 Bus, both at Harford Mall. By the late 1990s, all crossroads along this portion of MD 24 had full traffic signals. This included one at a new road, Marketplace Drive, that was built to keep up with increasing construction of retail in Bel Air. Congestion on new 24 now rivals that of old 24 pre-1987. The interchange with MD 924/Tollgate Road which opened in 2011, and is partially integrated with the I-95 interchange, helped somewhat in that immediate area (the Constant Friendship section of Abingdon). In about the next three years MD 24 is supposed to be three lanes in each direction up to in between Singer and Wheel roads.

[jp the roadgeek]

The rebuild of the I-91/CT 15 interchange about 30 years ago created perhaps the biggest bottleneck between New York and Boston for traffic headed to I-84 from I-91 with a single lane ramp that is backed up for well over a mile 16 hours a day 7 days a week.  It is so bad they're replacing it with a high speed LEFT exit.