Traffic Calming

[Duke87]

It's a relatively recent phenomenon, but a lot of areas have taken quite a craze to it. Here's my thoughts:

There are places where it's good and places where it's not.
When you have a downtown area that you want to be pedestrian friendly, doing things like closing some streets to vehicular traffic, widening or bumping out the sidewalks, putting protected pedestrian phases in signals, etc. - it's productive.
On the other hand, once you get out of downtown into purely residential and somewhat suburban areas, and you start seeing speed bumps put in streets and dead ends created simply for the sake of creating dead ends, not because there's a good physical reason why the street can't go through... there's a problem. It hurts connectivity and the ability to travel for streets not to go through. Yes, I understand people don't like "outsiders" passing through their nice quiet street, but really... it's a public street. They have every right to. Besides which, if the major streets become congested or blocked, it's nice to have that redundancy which traffic can use to bypass the problem.
As for speed bumps, I understand that the idea is to make traffic slow down... but there's a problem here: it also makes emergency vehicles have to slow down.
If my house catches fire, I don't want the firetrucks arrival delayed by having to take the long way around because my street is needlessly a dead end, and/or because it has to slow down to go over speed bumps.
Besides which, I don't want to have to drive over speed bumps every time I come and go from my house. That would get real annoying, real fast.


Your thoughts on the matter?

[Truvelo]

It's well established over here. In London virtually every side street and some main roads have them. It's got so bad in the capital that one borough is removing them, see here.

In another case a resident removed a hump from outside his house because of the noise from trucks crashing over them, see here.

Where I live the council is still installing them under the guise 'Safer routes to school'. It has nothing to do with telling kids how to cross the road safety, all it does is penalise motorists. The road between my house and the freeway had humps installed a couple of years ago so now I take a slight longer route along a narrower road to avoid them.

I just hope your recent phenomenon turns out to be a short one.

[Chris]

In the Netherlands, nobody wants a speed bump, except in front of their house 

So, yes, it has gotten totally over the top here in traffic calming. Some streets have speed bumps every 150 feet.  Gimme back the 70's!

[deathtopumpkins]

Wow... I actually feel lucky to live in Virginia for once.  I can't recall ever seeing a speed bump/hump on a city street. Just in parking lots in front of a few older stores. New ones don't use them. And I've NEVER seen one near a school.

[froggie]

Wow... I actually feel lucky to live in Virginia for once.   I can't recall ever seeing a speed bump/hump on a city street.

Robin Hood Rd in Norfolk...


Going back to Duke's comments, areas away from downtown can go either way.  Sure, many of those streets are collectors or minor arterials.  But on the flip side, drivers often use those streets as if they were dragstrips or raceways, even in residential areas.  If the neighborhood even has the perception that drivers are going well over the speed limit on the street, they'll be agitating for traffic calming on that street.  Sometimes they're exaggerating the situation.  Sometimes they aren't.  But it's the times they ARE exaggerating that are giving traffic calming a poor reputation.

[Truvelo]

Wow... I actually feel lucky to live in Virginia for once.   I can't recall ever seeing a speed bump/hump on a city street.

Robin Hood Rd in Norfolk...

Which seems to be quite easily avoided by using Krick St instead. I suppose it depends how severe the humps are. The ones near me are really nasty which is why I will use an alternative route to avoid them.

[florida]

Speed tables!

In Tallahassee, FL, they have them on the more residential streets which are also cut-off/connecting roads, so either way you were screwed. Here in Orlando, they're used less frequently.

[agentsteel53]

speed bumps make me want to accelerate as hard as possible, then brake as hard as possible.  the exact opposite of the desired effect. 

also, multiple four way stop signs on the through route ... not good.

[roadfro]

My thoughts on various traffic calming measures:

Speed *bumps* should never be installed on a public street.  Speed *humps* are a decent method of traffic calming on public streets when installed correctly.  Certain cities (Las Vegas being one I know of for sure) will not install speed humps on primary emergency response routes, so as to not slow down fire/paramedic vehicles. 

I am not a fan of using stop control for traffic calming through residential neighborhoods.  Overuse of stop signs, especially where they are not warranted, just encourages motorists to disrespect the sign.  At intersections where calming is desired, I believe a mini roundabout can achieve the desired effect without the unnecessary stop.

Another good method is sidewalk extensions ("bulb-out") at intersections or marked crosswalks.  Making the street narrower (widening sidewalks, restriping, etc.) also works well, because the illusion of narrower lanes tends to make drivers a bit more uncomfortable and more likely to slow down.

On a busier street, a "road diet" can calm traffic.  This could involve taking an existing 4-lane road and turning it into 2-lanes with a center turn plus bike/parking lanes.  Not only does this tend to calm the traffic somewhat, it can also encourage multi-modal use.

Closing public streets should be considered as a last resort.  If there is considerable cut-through traffic in a neighborhood (which is often also speeding), then it may be better for the neighborhood.  Consideration should be given to a partial closure first (i.e. allowing egress but no ingress), though.

[agentsteel53]

how does the road diet approach work?  A road that is already at capacity for a given number of lanes, and then the number of lanes is reduced? 

[mapman]

Road diets are most effective at speed reduction on roadways that aren't very busy, and thus the extra through lane is somewhat superfluous.  For example, on a four-lane road through a small downtown district that was bypassed by a freeway.  As agentsteel52 suggests, if the four-lane road is very busy, instituting a road diet may create more problems than it would solve.

[Scott5114]

If you have problems with cut-thru traffic, then the problem you need to solve is not how to get people to stop using the cut-thru road, but whatever is wrong with the main roads that cause people to want to cut thru.

[roadfro]

Sometimes, though, there's going to be neighborhoods and/or arterials that will just lend themselves to cut-through traffic--often from the result of older planning standards.

As to the road diet issue: the road would not one that is at capacity, but rather more of a collector road that is somewhat commercial.  Sometimes, converting a four-lane section to two-lane plus center turn will actually improve the traffic flow, especially in cases where there is a lot of left turns made onto side streets or commercial driveways.

[Duke87]

If you have problems with cut-thru traffic, then the problem you need to solve is not how to get people to stop using the cut-thru road, but whatever is wrong with the main roads that cause people to want to cut thru.

Often it's simply that the shortcut is, well, shorter. And no improvement to the main roads is going to change that.

[agentsteel53]

one can always appropriately warp the space-time continuum 

[Bickendan]

Road diets are most effective at speed reduction on roadways that aren't very busy, and thus the extra through lane is somewhat superfluous.  For example, on a four-lane road through a small downtown district that was bypassed by a freeway.  As agentsteel52 suggests, if the four-lane road is very busy, instituting a road diet may create more problems than it would solve.

When the Yellow Line MAX got built on N Interstate Ave here in Portland, the entire length of Interstate got slimmed from four to two lanes, divided (as the light rail runs right down the middle). The biggest reason it worked is Interstate's proximity to I-5, running parallel about a quarter mile to the east (and while the Yellow Line is busy, I wouldn't claim it's solely responsible for reducing traffic, particularly trucks, from Interstate).

Oh, lovely memories of flame wars on m.t.u-t over the Yellow Line...

[Scott5114]

If you have problems with cut-thru traffic, then the problem you need to solve is not how to get people to stop using the cut-thru road, but whatever is wrong with the main roads that cause people to want to cut thru.

Often it's simply that the shortcut is, well, shorter. And no improvement to the main roads is going to change that.

Not shorter–faster. If taking the main road is a longer drive, but takes five minutes less time than going through a neighborhood, nobody will notice and they will stick to the main road.

Remember, everyone has every incentive to use the main roads, as they are indeed the main roads and therefore arguably should be the fastest route to anywhere. It's only when you have a perceived problem on the main road–say, a badly timed stoplight, or too many of them, or too low a speed limit, or too much traffic–that you generally have cut-thru traffic. Another possible reason is because there is no main road within an acceptable distance (see Springfield, MO south of Sunshine St.) So while it costs more to remedy these types of situations than it is to put in traffic calming, you will probably eventually have to remedy them anyway (in fact, it may become more urgent because now you have the traffic that was avoiding that road being forced onto it by the traffic calming). And remedies for the main road will make everyone happier in the long run.

[flowmotion]

They tried the "mini-roundabout" in my neighborhood and it proved to be quite deadly to pedestrians and bicyclists. About six months later, they were all ripped out.

I've once lived in an area where the four-way intesections were blocked off on the diagonal, and I thought it worked well and didn't disrupt access or emergency service.

[roadfro]

They tried the "mini-roundabout" in my neighborhood and it proved to be quite deadly to pedestrians and bicyclists. About six months later, they were all ripped out.

I'm interested to learn how mini-roundabouts were deadly to pedestrians & bicyclists.  Mini-roundabouts are typically designed such that an island is placed within a standard size intersection with no other treatments...not any more or less complex than a four-way intersection as far as peds & bikes are concerned.

[Bickendan]

And they work well in Portland, as well. I think they're more effective than street humps.

[Bryant5493]

They tried the "mini-roundabout" in my neighborhood and it proved to be quite deadly to pedestrians and bicyclists. About six months later, they were all ripped out.

I've once lived in an area where the four-way intesections were blocked off on the diagonal, and I thought it worked well and didn't disrupt access or emergency service.

A similar situation happend in Southwest Fulton County, just north of Camp Creek Parkway (S.R. 6) at the intersection of Westlake Parkway and Reynolds Road. The intersection is now a four-way stop intersection.


Be well,

Bryant

[roadfro]

So what specifically was the problem with the mini-roundabout that it was removed in favor of a 4-way stop?

[Bryant5493]

So what specifically was the problem with the mini-roundabout that it was removed in favor of a 4-way stop?

Not too sure. I only traveled through it once. The problem may've been people didn't know how to properly use it (i.e., stopping in the roundabout, failure to yield, etc.). Also, it was constructed poorly (and unkempt), not giving heavy trucks a large enough turn radius.


Be well,

Bryant

[Chris]

Decent roundabouts need at least a 60 feet radius (120 feet diameter) to allow trucks to turn. These are Dutch standards, they may be even larger in the United States because trucks are longer there.

In most of the US urban grid system, there's no ROW for a 120 feet diameter roundabout.

[Chris]

Here's  a very stupid traffic calming device in the Netherlands.

This poller makes you wait 3 minutes, then it lets a few vehicles through, and then you have to wait another 3 minutes.