Stop signs keep on getting added around Ludington. Recently, two were added to Washington at Bryant (making it a 4-way stop), two were added to Sherman at Woodlawn intersection and one was added to N James at Court Street (making both of the T-intersections a 3-way stop), among others. On Monday, another one on Stearn’s outer loop was proposed by Chief Barnett, who swears by stop signs. After all, stop signs slow traffic down, cost little to maintain, and make things safer. Right?
Let’s check the research. The Manual of Uniform Traffic Control Devices (MUTCD) is the bible of traffic engineering, and is fairly precise on where a stop sign is warranted, though a little more vague on where one is not. An abstract of an article I read recently said:
This paper reviewed over 70 technical papers covering all-way stops (or multi-way stops) and their success and failure as traffic control devices in residential areas.
This study is the most comprehensive found on multi-way stop signs. The study looked at how multi-way stop signs have been used as traffic calming measures to control speed. There have been 23 hypotheses studied using multi-way stop as speed control. The research found an additional 9 hypotheses studied showing the effect multi way stops have on other traffic engineering problems.
The research found that, overwhelmingly, multi-way stop signs do NOT control speed except under very limited conditions. The research shows that the concerns about unwarranted stop signs are well founded.
A link to the complete paper is at the end of this brief summary, and is a good read for those who are intrigued by this counter-intuitive concept. The findings among the various studies:
1) Multi-way stops do not control speeds, nor do they reduce speeds on residential streets.
2) Stop compliance is poor where a sign is unwarranted (meaning it is there despite the MUTCD’s rules) at a multi-way stop. Speeds actually increase at a distance from the intersection as motorists “make up that time”. Overall, speed decreases when such stop signs are removed!
3) Safety of pedestrians at such unwarranted signs is decreased, esp. for children, as they expect the vehicles to stop, while many motorists have gotten in the habit of running the sign. Yet, people “feel” safer with the sign, warranted or not.
4) Unwarranted multi-way stops may present potential liability problems for a governing unit’s undocumented exceptions to accepted warrants. Many times the unwarranted stop signs are installed without a warrant study or some documentation.
5) Stop signs increase noise and pollution in the vicinity of an intersection. The noise is created by the vehicle braking noise at the intersection and the cars accelerating up to speed. The noise is created by the engine exhaust, brake, tire and aerodynamic noises.
6) Multi-way stop signs have high operating costs based on vehicle operating costs, vehicular travel times, fuel consumption and increased vehicle emissions.
7) Unwarranted stop signs do not significantly change the safety of an intersection.
The only positive effect on safety that an unwarranted stop sign may have, according to these studies, is if there are limited line-of-sight issues caused by objects at the street corners or parked cars. It may be best to remediate those issues, however, and then remove the unwarranted signs.
The Economics of Multi-way Stop Signs
The most profound piece of this study comes from reference 55 which determines the economic impact of having an unwarranted stop sign. Presuming 8000 cars pass through such an intersection each day (probably close to the total that goes through the Washington-Bryant signs per day during the summer) the yearly costs added to the traveling public is $210,061 in 1990 dollars (over $350,000 inflation adjusted). Since the multi-stop at Washington-Bryant was introduced mid-April, the traveling residents/visitors of Ludington have been burdened with about $150,000 extra costs just due to these two new signs!
Operating Costs (1990) $ 111,737/year
($.04291/Stop)
Delay & Travel Costs (1990) $ 88,556 /year
($.03401/Stop)
Enforcement Costs (1990) $ 837/year
Cost of Fines (19 per year) $ 1,045/year
Cost of 2 stop signs (1990) $ 280
Costs of increased insurance (1990) $7,606/year
Total (1990) $210,061/year/intersection
The study summarizes its findings:
Researchers found that multi-way stop signs do not control speed. In analyzing the 23 hypotheses for multi-way stop signs, five were favorable and 18 were unfavorable toward installing unwarranted all-way stop signs. The Chicago study (6) was the only research paper that showed factual support for "unwarranted" multi-way stop signs. They were found to be effective at reducing accidents at intersections that have sight distance problems and on-street parking. Benefits to control speeds by installing multi-way stop signs are perceived rather than actual and the costs for the driving public are far greater than any benefits derived from the installation of the multi-way stop signs.
The proposed stop sign at the east side of Ludington Avenue where it crosses Lakeshore Drive, was approved by the council 5-1, Monday. Only Councilor Engblade saw the futility of this sign and asked the Chief whether there had been any accidents there (to which he replied "nothing recently"). The "determined hazard" was not even a hazard to start with.
If we accept the validity of these 71 studies, the best way to improve the multi-way stops at Washington-Bryant is to unearth the two signs on Bryant. At Sherman-Woodlawn, ditch the two signs on Sherman. At James-Court, remove the two signs on Court. And don't put one on West Ludington Avenue. Only then will we be following the MUTCD and making the streets safer, travel more economical, and traffic more fluid. It’s been proved!
http://www.troymi.gov/TrafficEngineering/Multiway.htm
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