Myths, Realities, and Frequently Asked Questions
About Speed Bumps and Intersection (Traffic) Circles
"Time delays have a more negative impact on people the farther they are from help. A 30-second delay in an emergency response is more detrimental to people when added onto a six minute response than when added onto a two minute response. Full-blown traffic mitigation on emergency response routes will disproportionately impact citizens living and working at the edges of Fire Department response districts."
Boulder Fire Chief Larry Donner, March 12, 1997
Index:
Myth: "Boulder's neighborhood streets are unsafe for pedestrians and cyclists."
Accident and Emergency Call Trends, 1992-1999
Accident and Emergency Call Totals, 1992-1999
Myth: "Fire departments in other cities approve of bumps and circles."
Myth: "Lowering speed limits will make the streets safer."
Myth: "Traffic mitigation devices reduce the accident rate."
Myth: "Traffic circles are safe for pedestrians and cyclists."
Myth: "Boulder's neighborhood streets are unsafe for pedestrians and cyclists."
Reality: Claims that Boulder's neighborhoods are made unsafe by speeding cars are factually unsupportable. From 1992-1999 there were five fatalities in auto/pedestrian accidents, all on our busiest arterial streets, none in neighborhoods. Non-fatal accidents averaged about 51 per year and are not increasing despite traffic growth. All but a scattering of these 413 accidents occurred on just six arterial streets-Broadway, Canyon, Arapahoe, 28th, 30th, and Table Mesa west of Broadway. Objective evidence shows convincingly that effective pedestrian safety initiatives would focus on commercial districts and multi-lane roads, not local streets. Return to page Index
Accident and Emergency Call Trends, 1992-1999
Accident and Emergency Call Totals, 1992-1999
Myth: "Fire departments in other cities approve of bumps and circles."
Reality: Fire departments EVERYWHERE have opposed the devices, including those in so-called "progressive" cities like Seattle, Washington and Portland, Oregon. A fire chief in Portland states that their transportation division did not involve them at all in the initial stages of their project and in fact would not allow them to express their concerns publicly. A firefighter in Seattle stated that they gave up trying to oppose them, and that some of their larger trucks cannot get around the circles. One must remember that fire chiefs are city employees, and some are more willing than others to speak out. Return to page Index
Myth: "Mitigation devices have been used in other countries for many years with no problems or public opposition"
Britain’s Transport Research Laboratory, a scientific research organization which originated the design of the speed “hump”, reversed its support for the devices after receiving numerous complaints of “excessive noise, vibration, increased vehicle emissions and significant increase in accidents involving cyclists and motorcyclists”. TRL report #307 recognizes a conflict between vertical devices and the desired shift to public transportation, as the devices “cause damage and increase maintenance to buses and cause physical problems to drivers.”
Towns and cities throughout Britain are to spend millions of English pounds lowering or removing 500,000 speed humps to accommodate buses which must meet new disability regulations to allow wheelchair access. “Until this happens, roads with humps have been declared bus-less zones.” (The London Telegraph, Feb. 27, 2000.)
The “success” of the use of the devices can be attributed to the lack of a democratic process for their installation. In 1999, the residents of the city of Leicester, England collected 500 signatures out of 700 homes to express their objection to an installation of humps in their town. It was discovered pamphlets were published rubber-stamping the project before the meeting of the councilors to consider the petition even took place. Such “success” is sought by some members of our Boulder City Council. Return to page Index
Myth: "Lowering speed limits will make the streets safer."
Reality: According to a Federal Highway Administration study titled "Driver Speed Behavior on U.S. Streets and Highways", by Samuel C. Tignor, Ph.D., chief of the Traffic Safety Research Division at FHA, establishing speed limits above or below the 85th percentile speed causes more accidents. The study states: "Properly established speed limits foster voluntary compliance and separate the occasional high-risk driver from the vast majority of drivers. On the other hand, speed limits which are set artificially low tend to be ignored and misallocate resources, apprehending and prosecuting motorists driving at safe speeds. Over time this could lead to a loss of respect for all speed limits and create the impression that traffic law enforcement and the judicial system are unfair. Return to page Index
Myth: "Traffic mitigation devices reduce the accident rate."
Reality: Boulder's own statistics do not support this statement. Accidents increased dramatically in the two years after the experimental devices were installed in Whittier and Balsam/Edgewood. Winter conditions at the traffic circles cause unprecedented pileups. One particularly bad snowstorm in 1997 yielded 6 traffic accidents at the traffic circle on 17th and Pine in 12 hours. Traffic accidents between Broadway and 20th on Norwood were virtually non-existent prior to installation of traffic mitigation. Norwood has experienced two very serious traffic accidents directly related to traffic mitigation devices since installation. This despite that the mild winters over the past three years have meant fewer accidents in general.
The most recent report on traffic calming in the U.S. was commissioned by the Federal Highway administration and the ITE (Institute of Transportation Engineers) in 1999. Reid Ewing, urban planner and self-professed supporter of the devices, authored the report. Ewing acknowledges assessment of the safety benefits of calming devices is inconsistent at best. Ewing states: "One reason for these mixed results may be due to statistics. Traffic calming in the U.S. is largely restricted to low volume residential streets. Collisions occur infrequently on such streets to begin with, and any systematic change in collision rates tends to get lost in the random variation from year to year. This limits our confidence in drawing inferences about safety impacts of traffic calming." (Traffic Calming: State of the Practice, 1999 p. 111)
A paper presented by Gerald J.S. Wilde, Department of Psychology, Queen's University, Kingston, Ontario titled "Can traffic calming devices be expected to reduce the accident rate per head of population or per unit distance driven?" states the following: "...there is a paradox between some popular safety policies. This is all the more puzzling as these different safety policies may well be implemented simultaneously and even by the same accident prevention agency. The first policy aims to reduce the severity of the consequences of risky behaviour by the installation of seatbelts, airbags, crash barriers, wide and forgiving roads, collapsible lamp posts, crashworthy vehicles and so forth. The second policy is to increase the severity of the consequences of imprudent behaviour and thus to 'scare people into behaving safely.' Examples are speed bumps, narrow street passages, barbed wire, rumble strips, pavement undulation, chicanes, speed tables, traffic throttles or pinch points. ...measures aimed at reducing traffic and rapid traffic flow increase the accident rate per kilometer driven." Return to page Index
Myth: "Traffic circles are safe for pedestrians and cyclists."
Reality: Boulder Bicycle Commuters (BBC) adopted an official policy against traffic circles in 1997. They continue to hold this policy to date. According to BBC, traffic circles are "Too expensive, dangerous, intimidating to new cyclists, confusing to many motorists..." The Federal Highway Administration State of the Art Report On Residential Traffic Management states the following about traffic circles:
"...While no formal statistics exist on traffic circle safety, considerable observations have been made of unsafe practices caused by circles. They present an increased hazard to pedestrians by bringing vehicles, some at relatively high speeds, nearer to the curb where the pedestrians are waiting. The deflection they cause to an automobile can also impinge upon a bicyclists path......The lack of substantiating accident statistics tend to speak more to the short time of usage and usage on low volume streets rather than necessarily indicating inherent safety of the devices....Traffic circles should not be located where a clear pedestrian or bicycle demand may create conflicts as noted above." Return to page Index
Myth: "Traffic congestion delays emergency response, so delays caused by traffic mitigation are irrelevant."
Reality: While traffic congestion does adversely impact emergency response, it is a transient condition focused on arterial roadways. It also makes no sense whatsoever to dismiss delays caused by traffic mitigation simply because congestion can also be a factor in sub-standard emergency response. Delay, however incurred or imposed, is deadly. Traffic mitigation devices impose a permanent, 24 hour per day delay on response times. Since these devices are being proposed for neighborhood streets that don't experience congestion, they are undoubtedly the principle cause of delay. In fact, according to the April 8th, 1997 NTMP Status Report written by Boulder's Public Works Department, Page 23, Paragraph 7,
"In 1995, 97% of the responses to the Pine corridor had a response time of 6 minutes or less, while only about 88% of the calls City-wide met the 6-minute criteria. Between 1995 and 1996, the response time for this corridor increased 27.8 seconds compared to an overall increase of 6.21 seconds for the City. Similar degradation curves are found at the 5 and 4 minute response levels. The Department's analysis shows that the degradation is statistically significant and highly correlated to the mitigation devices. There is a 99.989% chance that degradation in response time is related to traffic mitigation. Out statistical evidence also shows that 0.5% of the response time degradation is due to other system-wide factors." Return to page Index