ABSTRACT
As the Fire Chief of a department, or, the Fire Marshal approving new developments, you have many challenges before you. However, nearly all of these challenges evolve around the safety of the public as well as of your employees. Your employees are the greatest asset of your fire department, and the jurisdiction to which you serve. Can your department support a road design that ultimately can cause serious or debilitating injuries to your personnel? Can your department support road designs that will ultimately delay your service or cause further injuries to your patients? And, last, but not least, can your department support a road design that can cause damage to the fire apparatus that your department uses to protect the life and property of your community?
The fire services, as well as other emergency responding agencies are tasked with the enormous job of protecting and serving the public. However, there are forces that are just as impassioned about another kind of safety, the protection of persons and property from speeding vehicles by installing speed humps/bumps in residential neighborhoods.
This paper will provide information about the installation of traffic calming devices, specifically speed humps/bumps. This paper is intended to educate all stakeholders in the process and problems associated with traffic calming devices, and to further educate these stakeholders of alternatives that can used to create safer neighborhoods without the installation of speed humps/bumps. To help address the different issues, this paper highlights eight specific categories: increased response times, additional traffic on alternate routes, vehicle damages,
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increased property damage, injuries because of vertical jerks, civil liability, environmental impacts, and the possible violation of the Americans with Disabilities Act.
The result of this paper is the recommendation that the fire service, the Department of Public Works and the Board of Supervisors of Santa Cruz County redefine the process for approving the installation of traffic calming devices and look at the many alternatives available before settling on, as has been the practice, speed humps/bumps.
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TABLE OF CONTENTS
Introduction …………………………………………………………………………… 4
The Issue ……………………………………………………………………………… 6
Increased Response Times ……………………………………………………………… 8
Increased Traffic on Alternative Routes ………………………………………………..10 Increased Vehicular Damage ………………………………………………………….. 11
Increased Property Damages ………………………………………………………….. 12
Injuries ………………………………………………………………………………… 12
Civil Liability ………………………………………………………………………… 13
Environmental Impacts ………………………………………………………………. 14
Violation of Americans With Disabilities Act ………………………………………. 15 Conclusion …………………………………………………………………………… 16
Recommendation …………………………………………………………………….. 17
References …………………………………………………………………………… 19
Appendix A ………………………………………………………………………….. 21
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INTRODUCTION
As the Fire Chief of a department, or, the Fire Marshal approving new developments, you have many challenges before you. However, nearly all of these challenges evolve around the safety of the public as well as of your employees. Your employees are the greatest asset of your fire department, and the jurisdiction to which you serve. Can your department support a road design that ultimately can cause serious or debilitating injuries to your personnel? Can your department support road designs that will ultimately delay your service or cause further injuries to your patients? And, last, but not least, can your department support a road design that can cause damage to the fire apparatus that your department uses to protect the life and property of your community?
This paper is a result of an increasing desire of people to have speed hump / bumps installed in their neighborhoods. Those wanting the speed hump / bumps installed use “public safety” as their concern, when in fact, if that were the real reason, they would realize that such an impediment actually can threaten public safety for the entire neighborhood. The term “Traffic Calming Devices” leads one to believe that by installing such appurtenances on a roadway, that traffic and speed is reduced in a neighborhood, and that the neighborhood is safer. In some cases, the installation of traffic calming devices may add to the safety of a neighborhood, but to what expense?
The fire service through study of historical data has developed over a number of years an acceptable level service for the population that they serve. This service level is called the Standard of Response Coverage. Standards of Response Coverage (SORC) are those written procedures determining the distribution and concentration of fixed and mobile resources. The process includes reviewing community expectations, setting response goals and establishing a
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system of measuring the performance. This plan, when properly implemented assists an agency determine proper resource deployment. The SORC process uses a systems approach towards deployment rather than a one-size-fits-all prescriptive formula. An example would be adequate resources arriving on the scene of a residential room and content fire within 5 minutes from time of dispatch, 80% of the time; or, to be able to start advanced life saving measures for a heart attack patient within 4 minutes of notification 80% of the time. If resources arrive too late or are understaffed, the emergency will continue to escalate, drawing more of the agency’s resources into a losing battle. The SORC assists in determining what or how many fire companies must arrive, if they are to save lives and limit property damage in a structure fire, by arriving before flashover has occurred. Flashover is the stage of a fire where all of the contents in a room have been sufficiently heated to ignite simultaneously. Ensuring resources arrive in time to prevent flashover or to save patients from medical emergencies is one of the toughest challenges for chief fire officers today. The installation of speed-reducing devices only adds to the difficulty.
Most emergency medical incidents require the quick response of firefighters and resources to limit the suffering and to rapidly intervene in life-threatening situations. As in the fire scenario, a rapid response with the appropriate equipment and personnel is imperative for a successful outcome for the patient(s).
In the past 15 years, there have been a number of studies about the installation and use of traffic calming devices. It is hoped that this paper will address the impacts on a community when these devices are installed. Particular emphasis will be on the use of speed hump/bumps.
To help address the different issues, eight specific impacts of traffic calming devices will be discussed: increased response times, additional traffic on alternate routes, vehicle damages,
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increased property damage, injuries as a result of vertical jerks, civil liability, environmental impacts and the possible violation of the Americans with Disabilities Act of 1990.
THE ISSUE
In recent months, there has been an increase in the requests for the installation of speed humps/bumps throughout the County of Santa Cruz. As part of the process, the fire authority is notified about the request by the applicant(s). The applicant is required to get a letter from the fire authority to document that they have been consulted, regardless of whether the fire authority is in favor or not of the installation of the speed hump/bumps. It appears, regardless of what the letter states, that the County of Santa Cruz will grant the installation of speed humps/bumps if a neighborhood desires them, even when it can be shown that the installation will have a detrimental effect on the overall fire and medical service delivery in a neighborhood. In fact, when questioning a member of the Board of Supervisors about the practice of approving all of the requests, I was told that if we (the fire service) wanted to be heard about speed humps/bumps, that we needed to “stop opposing every one of these requests”. The opposition of speed humps/bumps is sound and there are alternatives that can achieve the same results at a much lower cost to all parties involved, especially if the County of Santa Cruz must defend itself in a liability or ADA lawsuit.
The control of vehicle speeds and an acceptable level of safety within a residential neighborhood are especially important. The desires of the residents to have speed control devices installed in their neighborhoods is understandable. However, public safety agencies charged with the protection of life, property and the environment must weigh in on the debate
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and ensure that those persons approving installations of such devices are educated and informed of the consequences, negative and positive, of their decisions.
According to the Santa Cruz County Public Works Department, they subscribe to designs consistent with those published by the Institute of Transportation Engineers in a document entitled “Guidelines for the Design and Application of Speed Humps”, 1997 Edition. However, it is interesting that a comprehensive study commissioned by the Institute of Transportation Engineers and the Federal Highway Administration concluded as follows:
“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”. (Reid Ewing, 1999)
Interestingly, speed humps/bump are intended to reduce the frequency of accidents, however, the data is not conclusive in this regard. Moreover, some evidence suggests that traffic calming devices may actually increase the occurrence of accidents. As an example, experimental speed humps were placed on a street in front of a school in Portland Maine, and vehicle accidents increased 35% (Kathleen Calongne, January 2003). Other jurisdictions have reported an increase of as much as 50%.
Transportation staff member Bill Cowern supplied data showing that deaths from traffic accidents for the entire City (Boulder, Colorado) averaged about 2.8 per year for 1991 through 1996. However, only one death, about 0.17 deaths per year, occurred on streets slated for treatment under the Neighborhood Traffic Mitigation Plan…. Because the
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mitigation devices themselves present some direct hazards, they could possibly cause more deaths by accidents rather than fewer. (Bowman, R, April 3) Delays in emergency responses due to traffic calming devices have been the subject of many studies, and as a result, a number of cities now have moratoriums in place and have even required the removal of such devices. Speed hump/bumps, have been identified as contributing to the deaths of people, both from causing an increase in response times, in addition to deaths as a resulting from the effects of hitting speed humps/bumps themselves while riding bicycles and skateboards. Additionally, there are documented injuries to firefighters, and other emergency response personnel, some of which have resulted in temporary or permanent disability.
INCREASED RESPONSE TIMES
The governing bodies typically determine an acceptable level of emergency service by balancing response goals with financial capabilities. The acceptable service level describes the level of response and care that can be expected by the community. The level of service is further used to determine, among other things, station locations. An example of station location is the ability to have water on a hostile fire within 5 minutes of notification 80% of the time; or to be able to start advanced life saving measures for a heart attack patient within 4 minutes of notification 80% of the time.
Sudden cardiac arrest (SCA) is the most common critical emergency needing prompt intervention. Sudden cardiac arrest strikes more than 350,000 people annually in the United States alone. According to the American Heart Association, nearly 90% of sudden cardiac arrest incidents occur outside the hospital environment. Studies also show that approximately 90% of those people treated within the first 2 minutes will survive, while only about 10% survive if
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treated after 6 minutes. Each speed hump/bump encountered on a response route, however, can add anywhere from 9 to 30 seconds to a response. In the case of a sudden cardiac arrest requiring transport from the scene to a hospital, you must again add those delay times into the equation because the ambulance must traverse the same hump/bumps twice. The delays caused by the installation of traffic calming devices can significantly erode a community’s accepted level of service.
Meanwhile, there are approximately 5,000 pedestrian deaths per year in the United States. A ten-year study of pedestrian deaths by the US Department of Health and Human Services, found 35% of pedestrian victims were intoxicated. (Calongne, January 2003) Communities are installing speed humps / bumps to protect pedestrians, but this is having a detrimental affect on response times to sudden cardiac arrests which are a much larger public health concern.
There are a number of articles available on the Internet and below is a small sampling of what is available. Most of the pages viewed had multiple links to other resources.
IAFF Canadian Journal, Volume 4, Issue #1, 2000 (Unknown, 2000) “Speed hump/bumps are a workplace hazard for fire fighters. – City Councillor …Speed hump/bumps ‘have significantly reduced the response times of all emergency vehicles responding to 911 calls…
…speed hump/bumps are a no-win situation for fire trucks. If taken at any speed, they can result in fire fighter injury – even seat-belted fire fighters can strike their heads on the roof of the cab, and there are cases of vertebral compression leading to permanent disability.
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Slowing a truck for speed hump/bumps or navigating other traffic calming devices adds to response time, adding crucial seconds at a time when every second counts.”
Coto de Caza, Channel 2, Los Angeles, CBS News, October 7, 1998 (Coto Decaza, 10/7/98) “Fire Officials complain that their 13-ton engines must slow to a crawl over these humps, letting precious seconds tick by while potentially life-threatening situations go untreated, the wire service said. Otherwise, firefighters who speed over the mounds might otherwise damage delicate equipment such as defibrillators or snap a fire engine’s suspension like a twig.” Memorandum of Roseville CA Fire Department’s Time Trials, Goals & Recommendations Documented in a test conducted by the Roseville CA Fire Department- “…emergency response time increased 10 – 12 seconds per speed hump.” (Tahti, June 4)
INCREASED TRAFFIC ON ALTERNATE ROUTES
As illustrated by the following quotes from various sources, installation of traffic calming devices in selected areas may just have the effect of diverting traffic to other streets. Based on your own driving experiences, how many times have you diverted to another street because of traffic calming devices in your route of travel? Had those devices not been in place, would you have altered your route of travel?
“Diverters and speed humps cause emergency response vehicles to take alternative routes, instead of the most direct route to the emergency. Installation of diverters can cause traffic to be diverted onto other streets. This in turn further
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increases response time due to heavy traffic”. (U.C. Neighborhood Transportation & Traffic Plan, 5-8-1995)
“Speed humps along a street can divert traffic to a nearby route. If traffic engineering studies show that the diverted traffic may cause equal or greater problems on a nearby route, speed humps should not be installed.” (Duane Smith & Karen Giese, September 1997)
We have all driven on those roads that have speed humps/bumps installed and realize that if there is another route to get to the same location without going over speed humps/bumps, we do it. Some of the reasons that we try to avoid them are common sense reasons. We do not like the bone jarring effects and do not care to damage our own vehicles, so why insist that emergency personnel put up with the same negative effects or take a longer route to an emergency.
INCREASED VEHICULAR DAMAGE
There is a concern that traffic-calming devices cause damage and increase maintenance to fire apparatus. Driving over these devices causes erratic weight shifts that can increase flexing and stress to suspension components such as steering, axles, and frames.
Examples of damages from speed bumps have been documented by Santa Cruz (CA) Fire Department, Fresno (CA) Fire Department, Berkeley (CA) Fire Department, and Sacramento (CA) Fire Department. All of these departments have experienced cracks in apparatus frames.
In the case of Sacramento (CA) Fire Department, they also have documented flattened springs, and body welds breaking from the frame. Sacramento (CA) has further documented two, potentially catastrophic incidents, including shearing off of the front axle as it crossed a speed
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hump/bump, and depositing equipment on the roadway after compartment doors sprung open while crossing a speed hump at 20 m.p.h., the speed hump was designed for a speed of 25 m.p.h..
San Diego (CA) Fire Department experienced a failure of a water tank on an engine as it rolled over a speed hump. (Ronald Powell)
Some special transit vehicles for the disabled have also reported increased maintenance from continually going over or around traffic calming devices. As a result of damage to their bus fleet, the City of Sacramento no longer provides bus routes on streets that contain speed humps.
This reduction in access to public transportation has become an A.D.A. issue that will be discussed later in this paper.
Damages to heavy equipment can become quite costly depending on the type and age of the apparatus involved. Major suspension damage to an older piece of apparatus may well render that particular piece of equipment out of service permanently and require a department to purchase a replacement vehicle. Depending on the type of apparatus, replacement costs may be as high as $750,000.
INCREASED PROPERTY DAMAGES
In a 2003 study conducted by the National Highway Transportation Safety Commission, it was found that rear-end collisions had increased 475% as a result of drivers colliding into vehicles slowing for speed hump/bumps. Damages are not confined to just rear-end collisions though, other damages also can result from a vehicle leaving the roadway and crashing into other parked cars, fences, poles, and structures as a result of the driver losing control of their vehicle.
In addition to the obvious damage as described above, studies conducted in the United Kingdom show that certain soil types can transmit harmful tremors straight into the foundation of
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a building causing it to crack. The damaging tremors can be amplified when vehicles shift weight while traversing speed humps.
INJURIES
Speed humps / bumps are causing growing numbers of injuries and even deaths. According to the National Highway Traffic Safety Commission, speed humps contributed directly to the deaths of thirty-seven people in 2002 alone. Severe injuries can occur to the head, neck, and spinal vertebrae, along with various strains and/or bruising whenever a vehicle goes out of control after crossing a device and striking another vehicle, fixed object, and/or a pedestrian. (Sanchez V. Austintown Township Trustees, 1986) (Harrington V. Labelle's Of Colorado, Inc, 1988). Ironically, these devices have typically been installed with the argument that they will improve public safety.
Air bag deployment has also become a concern of automobile manufacturers. Nissan has had four confirmed deployments by vehicles hitting speed humps and potholes. One such deployment resulted in the expected injuries to the driver and passenger, including facial, chest, and hand/arm injuries. (Bryon Bloch, 8/4/97)
Speed humps / bumps can compromise patient care during ambulance transport. Life saving measures are very difficult if not impossible, to start while traveling over speed humps / bumps.
Patients with cervical spine injuries may become further injured while bouncing over speed humps / bumps even while traveling at a very reduced speed. (Michael J Migliore, Assistant Fire Chi, May 8)
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CIVIL LIABILITY
According to a study conducted by the California Highway Patrol and the Auto Club of Southern California, drivers failed to obey other rules of the road while traversing streets with speed humps / bumps. Drivers failing to stop completely at STOP signs immediately following a series of speed hump / bumps increased 257% percent. 88 % of drivers start ignoring other road safety signs, actually increasing the overall risk of accidents and injury in the neighborhood.
Speed humps are not recognized by the State of California as an official traffic control device. Injuries caused by speed humps may result in significant additional liability for the County of Santa Cruz.
Some jurisdictions have been sued for personal injuries because of an encounter with speed hump/bumps. Because of the added liability, there are an increasing number of jurisdictions that are rejecting them as standard traffic control devices on public streets. Studies show that no single type of speed hump/bump is more successful in safely controlling speeds of all types of vehicles. In fact, the studies all tend to point out that depending on the suspension of a vehicle, and the speed of travel, some cars actually perform better at higher speeds than what the hump/bump is designed for. Some California jurisdictions that have banned speed humps/bumps due to liability and safety concerns are the City and County of San Diego, Cities of Chino Hills, Rancho Cucamonga, San Luis Obispo, Huntington Beach, Berkeley, Coto de Caza, Santee, and Sacramento. Some of these bans are a result of the jurisdiction unsuccessfully defending themselves in a legal action, and others are a result of a threat of legal actions.
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ENVIRONMENTAL IMPACTS
There have been a number of studies conducted to determine what if any effects speed humps/bumps have on the environment. The different studies show that there is an increase in the pollutants emitted from vehicles because of slowing and accelerating for these devices.
Nitrogen oxide (NOX) increased ten times, carbon monoxide (CO) increased three times, carbon dioxide (CO2) increased 25%. Volatile organics increased 46%, and unburned hydrocarbons increased by as much as 70%. One such study was done in Chico CA. And in addition to the expected increase in pollutants, it was determined that by removing the speed humps/bumps, that not only would the harmful effects of the pollutants be reduce, but that there would be an increase in fuel conservation.
VIOLATION OF A.D.A.
As the American with Disabilities Act (A.D.A.) matures and is amended to better meet the demands of the disabled, and the disabled community continues to question and demand better access to facilities, more legal challenges will be seen. One issue that will receive increasing attention is the charge that speed humps/bumps cause unnecessary pain, suffering and injury. In view of this concern, communities such as Sacramento (CA) have curtailed para-transit services on streets with speed humps/bumps. This has resulted in ADA lawsuits claiming reduced access to public transportation for people suffering from physical disabilities. §35.104 of the A.D.A defines a facility as any portion of buildings, structures, sites, complexes, equipment, rolling stock, or other conveyances roads, walks, passageways, parking lots, or other real or personal property, including the site where building, property, structure, or equipment is located. It appears that the authors of the A.D.A. had the foresight to recognize that
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any alterations made to these same facilities could pose a problem for people with disabilities and address both new construction as well as alterations. §35.151 (b) defines alteration as “Each facility or part of a facility altered by, on behalf of, or for the use of a public entity in a manner that affects or could affect the usability of the facility or part of the facility, shall, to the maximum extent feasible, be altered in such a manner that the altered portion of the facility is readily accessible to and usable by individuals with disabilities, if the alteration was commenced after January 26, 1992.” (Congressional Information Service, 2000) As a result of the wording contained within these definitions and reflected in a federal lawsuit, the court held “if a street is to be altered to make it more usable by the general public, it must also be made more usable for those with ambulatory disabilities.” (Kinney V. Yerusalim, 1993) By taking this position, the Federal Court has made entities that install traffic calming devices vulnerable to potential litigation for violation of the Americans with Disabilities Act.
Because of these legal implications, the City of Berkeley, in 1999 voted to indefinitely extend a moratorium on speed hump/bumps that they had implemented in 1995. That moratorium has since been changed to a permanent ban on the installation of speed humps/bumps for the City of Berkeley. According to the Berkeley Fire Department, and substantiated in a search of the Berkeley Dailey Planet, there is now an effort underway to remove the speed humps/bumps that had previously been installed. Additionally, issues are starting to arise from the installation of traffic circles in the center of intersections. The traffic circle, even though highly effective with slowing traffic speeds, is starting to produce a dangerous environment for not only the physically disabled, but also for pedestrians without disabilities. Furthermore, because of their design, traffic circles cause a reduction in the amount of much needed-on street parking to allow room for emergency vehicles to negotiate them without hitting cars, poles, mailboxes, etc...
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CONCLUSION
The use of speed humps/bumps as the only acceptable means of traffic calming must be questioned. The jurisdictions that allow the installation of these devices as the only means of slowing traffic in a neighborhood would be well advised to research the pros and cons of using these roadway devices. The future implications with respect to liabilities from damage, injuries, deaths, and traffic migration to alternate routes must be understood, and a decision must be made that best protects the community overall, both fiscally and physically. There is an abundance of information available about the subject of traffic calming devices and their applications. As with any change, the problem should be thoroughly studied, alternatives should be investigated and only after all data has been collected should a particular traffic-calming device be installed. The study must include input from the fire service, and other emergency response providers, as well as public transportation, prior to making any changes.
RECOMMENDATION
The decision to install speed humps/bumps as the preferred method of traffic calming needs more scrutiny than a petition of the neighborhood. Prior to considering any speed impeding or traffic control device, the department of public works should perform and document the following exercise to determine if in fact traffic-calming devices are the answer to the perceived problem.
1. Collect and verify current posted speeds
2. Current witnessed speeds
3. Stop sign observance
4. Pedestrian activities
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5. Traffic patterns for public safety, and public transportation While conducting the traffic study, the following process should be followed to determine if the roadway in question is a candidate for some type of traffic-calming device.
1. Enforce existing laws and ordinances regarding speed limits, revising if necessary. The City of Santa Cruz just recently increased the speed on eight neighborhood streets. This increase in speed was done after studying the average speeds on these streets, and the number of accidents or other incidents that had occurred as a result of the higher than posted speeds. The lower speeds because of normal traffic flow, were actually impeding the flow, and resulted in unnecessary citations being issued.
2. Educate the residents on the causes and reasons for the speeding problem and offer workable solutions.
3. Install alternate traffic control devices such as regulatory or warning signage in conformance with the MUTCD.
4. If the conditions warrant, install traffic control signage such as STOP signs or traffic signals in conformance with the MUTCD.
5. Consider installation of alternate traffic calming roadway features. Examples and descriptions can be found in Appendix A.
6. Consider legal liability. Speed humps/bumps are not addressed in the Manual for Uniform Traffic Control Device and public agencies have been held liable for damage and/or injury resulting from speed humps. It is important to document justification for all decisions made concerning installation and to review state and local laws to identify regulations pertaining to roadway design, roadway maintenance, traffic control, and other elements that might be related to the use of speed humps/bumps or other geometric design features.
7. Work with the various public safety and transportation agencies and departments that will be effected if traffic-calming devices are to be implemented. Consider a temporary installation to determine if the device of choice does meet the needs of all involved without compromising public safety.
8. The Santa Cruz County Department of Public Works in cooperation with all fire agencies within Santa Cruz County should create primary and secondary emergency response
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routes. Those routes that are determined to be primary response routes should receive the highest scrutiny for alternative traffic calming devices and avoid at all costs the installation of speed humps/bumps.
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REFERENCES
Kinney v. Yerusalim, 812 F. Supp. 547 (F. D. PA 1993).
Congressional Information Service. (2000). Nondiscrimination of the Basis of Disability in State and Local Government Services. (28 CFR 35.151). Retrieved 9/29/2004, from www.digital threads.com/utarpt/utarpt5
Michael J Migliore, Assistant Fire Chief. (May 8, 1995). U. C. Neighborhoods Transportation and Traffic Plan. Paper presented at Planning Meeting.
Harrington v. LaBelle's of Colorado, Inc., 732 p.2d (Montana 1988).
Sanchez v. Austintown Township Trustees, (Ohio Appelate 1986).
Bryon Bloch. (8/4/97). Speed Hump / bumps Can Cause Vehicle Airbag Activation. Save Our Streets, 1-2. Abstract obtained from Calming Programs & Emergency Response.
Ronald W. Powell. (May 31, 1996). The speed humps make hump / bumpy issue on Twain Street. San Diego Union-Tribune, pp. B-1.
Duane E. Smith, P.E. & Karen L. Giese. (September 1997). A study of Speed Humps. Ames, IA:
Iowa State University, Center for Transportation Research and Education.
National Motorist Association. Combating Traffic Obstruction Initiatives In Your Community.
The National Motorist Association. Abstract retrieved 10/1/04, from www.motorists.com database.
U.C. Neighborhood Transportation & Traffic Plan. Berkeley, CA: Department of Fire & Emergency Services
(10/7/98). Firefighters Want Speed Hump / bumps Hump / bumped. Los Angeles, CA: CBS News - Channel 2.
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Unknown. (2000). Traffic Calming Devices - Why fire fighters have given them a rough ride...".
IAFF Canadian Journal [On-Line serial], 4(1). Available www.digitalthreads.com/rada/slowdown.html
Reid Ewing. (1999). [Traffic Calming: State of the Practice]. P.123 Tahti, N. (June 4, 1991). Speed Hump / bump Information. Memorandum to the City Council.
Abstract retrieved 10/7/04, from www.digitalthreads.com database.
Bowman, Ray. (April 3, 1997). Deaths expected from Delayed Emergency Response due to Neighborhood Traffic Mitigation. City Council of Boulder Colorado. Abstract retrieved 9/29/04, from http://members.aol.com/raybowman/risk97/eval1.html database.
Calongne, K. (January 2003). Problems Associated with Traffic Calming Devices. National Motorists Association, 1 & 2. Abstract retrieved 9/29/04, from www. motorists.com database.
Kathleen Calongne. (January 2003). Problems Associated with Traffic Calming Devices. , 1.
Abstract retrieved 9/29/2004, from National Motorists Association database.
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APPENDIX A
The contents of this appendix should be consulted for alternatives to the conventional speed hump/bump. No one design should be considered better than another, each should be reviewed on its own merits and ability to achieve the desired outcome. Compare the desired outcome, current road designs, current road issues, and proposed alternatives when making the decision of installing traffic-calming devices.
CURB EXTENSIONS
By installing Curb Extensions, the
width of the roadway appears to be
narrower than it really is. By creating
such an illusion, the driver responds by
reducing their speeds to better negotiate
the perceived narrowing. The drivable
road width however is not reduced.
This option tends to be harder for fire apparatus to negotiate, however, the travel times are not critically compromised.
Photo by Institute of Traffic Safety Engineers
Intersection with Curb Returns
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ROUND-ABOUT
The round-about has long been used in many
European countries. Although confusing at
first, it has proven to actually reduce the
amount of time that a vehicle sits at an
intersection waiting to enter and pass through
when controlled by conventional traffic
controls such as stop signs or signals.
CIRCULAR ISLANDS
Circular Islands are easier to negotiate than
round-abouts. A circular island is an
obstruction in the path of the motoring public
and does not require that vehicles enter and
exit at different angles and locations as with
a round-about. A circular island can be
utilized in neighborhood intersections as well as major intersections of a city. The island adds beauty as well as functionality. Circular islands force drivers to reduce their speeds to safely negotiate around obstacles. The effectiveness for safety, however, can be compromised if the wrong landscaping is used. Because of reduced speeds, collisions are reduced. Disruption of traffic flows is reduced.
Photo by Institute of Traffic Safety Engineers
Round-About
Circular Island
Photo by Institute of Traffic Safety Engineers
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NARROW INTERSECTION WITH ISLAND
Raised islands in the center of the street that
forces a narrowing of the travel lanes. May be
used at intersections and along the length of a
street. Allows for landscaping, and a safe haven
for pedestrians crossing. Depending on the
street being treated, this option may reduce the
number of on-street parking spaces available.
RAISED INTERSECTION
Raised sections of the intersection utilizing
ramps on all approaches. The raised section
may be made of materials other than those used
in the roadway. Common materials used are
cobblestones, cement, bricks, or any other
material that will support the weight of vehicles
and produce a change in the texture. Because
the roadbed in the intersection is raised, accessibility for the disabled is not compromised, but proper marking and delineation of pedestrian ways is a must.
Photo by Institute of Traffic Safety Engineers
Narrow Intersection w/island
Photo by Institute of Traffic Safety Engineers
Raised Intersection
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CHICANE
Also referred to as dog-legs or serpentines,
the chicane is a series of alternating curb
narrowings that shift traffic from one side of
center to the other side of center. This form
of calming requires the driver to reduce
speeds to negotiate through the narrowing
and “moving” traffic lane. For a chicane to
be effective, the alternating must be down by placement of physical barriers. These barriers may include curbs, curb extensions, plantings, center lane dividers, or islands.
SPEED TABLE
A speed table is a long, wide, flat speed
hump that is raised above the traffic bed.
The raised section may be made of
materials other than those used in the
roadway. Common materials used are
cobblestones, cement, bricks, or any
other material that will support the
weight of vehicles and produce a change in the texture. The speed table is utilized mid-block of Speed Table
Photo by Institute of Traffic Safety Engineers
Photo by Institute of Traffic Safety Engineers
Chicane
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a street and because of this, may compromise accessibility for the disabled if no sidewalks are available. On-street parking is reduced when using speed tables. Similar to the raised intersection in performance and may incorporate crosswalks. A positive effect of the speed table is the reduced vehicular speeds if a crosswalk is desired as part of the design. Also, this design is easier for emergency vehicles to negotiate.
SPEED ENFORCEMENT
Although thought to be the least cost effective, speed
enforcement can reduce speeds in a troubled
neighborhood. Radar enforcement done either by a
police officer, or by an automated trailer as shown,
reduces speed. In order for an automated trailer to be
effective, a camera must also be incorporated with the
radar to capture the license and driver of the vehicle in a photo. Many cities are starting to install intersection cameras for red-light runners. If coupled with a radar, these intersection cameras could be modified to also photograph the speed violators.
The most recent adaptation of red-light enforcement in Santa Cruz County is within the City of Capitola on intersections that serve the Capitola Mall area.
Photo by Institute of Traffic Safety Engineers
Speed Enforcement
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SIGNAL LIGHTS
Signal lights are one of the more expensive
options available to a municipality to install.
Depending on the size of an intersection, and
the complexity of traffic patterns, the cost of
installation can be many tens of thousands of
dollars. The installation of signal lights many
times does not solve the problem of speed, and
in many cases only adds to the problem because drivers seeing the light changing from green to yellow will accelerate to get through the intersection prior to the lights changing to red. Signals are not a viable option either for neighborhoods with light to moderate traffic, and should never be used in the middle of a street, where the reduction of speed is the most beneficial.
Photo by Institute of Traffic Safety Engineers
Signal lights
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