chokers - effective traffic calming or roadway hazard?
chokers - effective traffic calming or roadway hazard?
(OP)
Have other traffic engineers successfully or unsuccessfully used chokers in residential streets to slow down traffic? I have seen material recommending the use of "chokers", meaning a narrowing of a local residential street to slow down the traffic. Typically a 60' residential street (40' curb to curb) has been reduced to 28' curb to curb at the choker, or sometimes a bit wider with a short narrow median island in the center. Parking is prohibited within the choker thus costing a property owner all on-street parking within their frontage. A concern is liability over what could be argued to be a roadway hazard artificially introduced into the street. Also the signing is problematic in that the choker requires prohibition of on-street parking and possibly an object marker at the entry point, plus median signage at the noses if a median is used. So, successful traffic calming device or safety hazard is the real question for consideration...





RE: chokers - effective traffic calming or roadway hazard?
I see no problems with a 28' choker. After all, it provides two 14' lanes, which is still wider than the standard lane width. I fyou wanted to, you could stripe it as two 10' lanes and an 8' parking lane.
Many of the things we do have drawbacks. An axample is guiderail. You can expect more crashes to occur at a location after guiderail is installed. Why? Because it is closer to the road than the object if protects traffic from.
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"...students of traffic are beginning to realize the false economy of mechanically controlled traffic, and hand work by trained officers will again prevail."
Wm. Phelps Eno, ca. 1928
RE: chokers - effective traffic calming or roadway hazard?
RE: chokers - effective traffic calming or roadway hazard?
The chokers in Europe usually only allow one car to pass regardless of direction. The Dutch, I believe, experimented with removing all traffic signs as a traffic calming measure -- surprisingly successfully. Their theory was that, if drivers have to figure out what's going on, they'll drive more cautiously.
RE: chokers - effective traffic calming or roadway hazard?
RE: chokers - effective traffic calming or roadway hazard?
The point is, not everything is judged on whether it is a hazard. For many things we do, the relevent question is, "Do the safety benefits outway the safety costs?" In this case, does the reduction in crash severity and(hopefully) frequency due to reduced speeds outweigh the costs of inattentive drivers running into the choker (plus construction costs, including DIs on the uphill side).
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"...students of traffic are beginning to realize the false economy of mechanically controlled traffic, and hand work by trained officers will again prevail."
Wm. Phelps Eno, ca. 1928
RE: chokers - effective traffic calming or roadway hazard?
If people are dumb enough, and yes I know that some are, to park directly across from someone and block the street, then a resident just has to call the police.
Heck, the street I live on was built in the 50's and is only 18 feet wide.
Also, with the 40 ft. right of way, we also have sidewalks on both sides with trees between the street and walk.
RE: chokers - effective traffic calming or roadway hazard?
RE: chokers - effective traffic calming or roadway hazard?
"Rat running" is a big problem through neighborhoods for residents, while a convenience to many more people who are using the rat runs. Looking from the perspective of society as a whole, one might say that traffic calming benefits few and harms many... until a child is killed by a racing motorist.
Subdivision designers should be careful not to design roads that will be attractive as thoroughfares I guess, but it is challenging, particularly in subdvisions of 500+ lots.
RE: chokers - effective traffic calming or roadway hazard?
It's an indirect bureaucratic answer to a responsibility problem.
RE: chokers - effective traffic calming or roadway hazard?
You are correct that traffic calming is not a perfect solution to a real problem. But then there is not a perfect solution. It is easy to say that the real solution is that people be responsible and drive an appropriate speed for the type of road and area that they are driving in.
However, experience shows that many people in this country do not do this. When people choose not to be responsible it is the job of government, specifically police departments and public works, to make people behave in a responsible fashion. The police can right tickets; studies have shown that this is generally not very effective. Public works (and design engineers) can make the roads less attrictive to drivers going faster than the prescribed speed. Does this make the road less convient? YES. That is part of the price that people in a society have to pay.
RE: chokers - effective traffic calming or roadway hazard?
Not true. Other people do not have to pay that price. Enforcement is the issue, not everybody's speed. A percentage of drivers will drive at an unsafe speed. You slow the safe speed of the throughfare, people slow down, but you still have people driving unsafe speeds - they're just slower because the safe speed of the road is slower. The answer is not to slow down everyone by making the road less safe at a given speed, the answer is to slow down the people driving too fast. "Traffic Calming" is a misnomer. It's true that enforcement is not the ideal answer, but it's certainly much closer to an ideal answer than slowing *everybody* down. We're talking urban environments with children running around, not freeways where enforcement is a part of the problem and not part of the cure.
RE: chokers - effective traffic calming or roadway hazard?
Wasn't the original poster asing about a residential street? Many traffic calming techniques are not meant to be used for collectors and arterials.
I was talking to a small city police chief last week who said his department has gone from 15 policemen to six. All the other policemen in the room nodded in agreement. We can't rely on enforcement anymore.
There are many places where roads are innappropriatly designed for their use (such as 40' wide residential streets). Blaming speeds on lack of enforcement when poor design plays a role is unprofessional.
The design speed concept evolving in ways I think are related here. Minimum design speed is on the way out. Consistent design speed between adjacent segments is gaining currency. With a minimum design speed of 30 mph, you can have a 30 mph curve at the end of a 4 mile tangent, and it meets your standard. The new approach gives you a red flag for sudden changes in effective design speed between adjacent segments.
As these changes progress, I expect a shift away from speed humps and towards alignments and cross sections that promote appropriate speed for the road's functional class and area.
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"...students of traffic are beginning to realize the false economy of mechanically controlled traffic, and hand work by trained officers will again prevail."
Wm. Phelps Eno, ca. 1928
RE: chokers - effective traffic calming or roadway hazard?
You could fault the designer or the subdivision regulations for turning residential streets into large speedways; you could fault the developer for favoring a longitudinal subdivision design that maximizes his number of lots.
Traffic calming has been shown to reduce accidents, particularly fatalities. It also reduces traffic noise. Residents who are displeased with traffic calming usually weren't consulted on the planning and design of the calming measures, which frequently results in unsightly traffic calming, instead of more attractive measures (landscaped islands, etc.). I would wager that traffic calming would raise property values, but I didn't find any evidence for this.
RE: chokers - effective traffic calming or roadway hazard?
Ultimately non sequitur. Making people stay at home also reduces accidents...
The question is how to make streets safe and not increase travel time. Some people don't mind additinal travel time. However, some people have a life.
RE: chokers - effective traffic calming or roadway hazard?
Some people have a life, and others have it stolen by a speeding motorist.
RE: chokers - effective traffic calming or roadway hazard?
RE: chokers - effective traffic calming or roadway hazard?
More importantly, however, why on earth does the fire department require 20' clear way? Their vehicles aren't that wide and if you're designing streets for traffic to pass around a fire truck during a home fire then those are the most ridiculous design criteria I've ever encountered. The former city engineer I worked with didn't even design his water reticulation network for peak flow and fire flow simultaneously: "I figure if a house is burning down, people will be on the street watching it, not taking a shower while doing laundry and running the dishwasher."
The "traffic calming" you're proposing provides more roadway than subdivision regulations around the country. In that context, it is not a hazard.
I would wager that any accidents would be due to people driving too fast on the 36' wide speedway that you're trying to calm.
You asked earlier where people would park if not on the street. Well, for a 70' wide lot, they could stack 3 or 4 (or even 5) cars on the street in front (on each side of the street). Presumably there's room on the lot for a double garage and a driveway; how many cars do these people need?
RE: chokers - effective traffic calming or roadway hazard?
RE: chokers - effective traffic calming or roadway hazard?
As far as "how many cars do these people need" I think that statement is a succinct summary of a specific attitude with respect to desire to control; certainly in concert with wanting to slow traffic.
RE: chokers - effective traffic calming or roadway hazard?
Here's Knoxville, TN:
Atlanta, GA (you may have to scroll down the side bar and click "more") has the following:
Residential access street and residential subcollector: ROW width: 32' Pavement width: 28'
RE: chokers - effective traffic calming or roadway hazard?
Short 6 foot wide islands ; one on each side of the street ; that take up one parking space...
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