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1. What is "traffic calming"? Traffic calming is the use of roadway geometrics and other physical measures to reduce unwanted effects of vehicular traffic, including excessive speeds, volumes (number of cars), and noise.
2. What types of roadway geometrics or physical measures are used by the City of Huntsville? The City has used, or will consider using, the following types of traffic calming measures: speed tables, "curb-outs", medians, traffic circles,"chokers", diverters, and total road closures. "Dips", or valley gutters, are installed only for drainage purposes and will not be installed for traffic calming purposes, due to significant impacts on emergency vehicle response time.
3. Are certain traffic calming measures better than others? There isn't one method that is "best"; each measure has its pros and cons. Moreover, it depends on whether the desired effect is to reduce volume or to reduce speed.
Measures such as diverters or road closures primarily attempt to reduce traffic volumes along a local street. Measures such as speed tables and "chokers" attempt to reduce vehicle speeds. Some of these measures are at least partially successful at reducing both speeds and volumes.
In general, the more restrictive the measure (e.g., speed tables, diverters, road closures), the greater effect it will have on reducing speeds or volumes, but it will also have a negative impact on those vehicles that may need to exceed the speed limit - for example, emergency vehicles. Also, the measures apply to everyone, so that residents are subjected to the same restrictions that are placed on the offending drivers. Drivers who do obey the speed limit may resent the more restrictive measures, and may complain that they are being penalized for the actions of a minority.
Less restrictive measures (such as medians, traffic circles, and curb-outs) have a less pronounced effect on reducing overall speeds or volumes, but do not have as adverse an impact upon emergency vehicles.
For a summary of some other cities' experiences with various traffic calming measures, and the relative effectiveness of these different measures, go to http://www.ite.org/traffic/tcsop/newappa.pdf
4. What is the difference between "speed cushions", "speed bumps", "speed humps", and "speed tables"? Speed cushions consists of recycled rubber. They are about 3 inches in height and 7 feet in the direction of travel. As the configuation shows, three (3) speed cushions are installed leaving a space or gap between each device. This spaching allows an emergency vehicle to straddle the devices with little if any delay.
Speed bumps are devices usually found in parking lots and are intended to keep speeds in the 10 MPH range. They are typically three to six inches high, and approximately one to three feet in the direction of travel. They are extremely jarring and abrupt, and are not appropriate for installation on public streets.
Speed humps are curved mounds of asphalt that are between three and four inches high, 12 feet in the direction of travel and keep speeds in the 15-20 MPH range.
Speed tables are about three-and-a-half inches high, and 22 feet in the direction of travel, and keep speeds in the 22-27 MPH range. They are constructed of straight lines rather than curves, and are gentler than speed humps.
While the City of Huntsville does not use speed bumps or speed humps, it does use speed tables.
5. What is the "85th Percentile Speed"? The 85th percentile speed is the most common measure that traffic engineers use when trying to describe the speed of a group of vehicles; for example, all cars traveling northbound on Jefferson Street at Holmes Avenue over a 24 hour period. Rather than an "average speed " of the pack, it is the speed that 85% of the cars are traveling at or below.
It is important to remember that 15% of the measured speeds are faster than this value, so that even though a street has an 85th percentile speed of (say) 35 MPH, it doesn't mean that there are not some cars traveling 60 MPH or more.
6. How do I request traffic calming for my street? Call either Traffic Engineering at 427-6850 or Huntville Police Department Community Relations at 427-7009, and request information on traffic calming for your particular street. Or, if you prefer to submit a request electronically, download a Neighborhood Traffic Calming Program Questionnaire complete the form, and submit it to Toneka Lindsey.
7. Once I turn in my questionnaire, how long does it take for the City to install traffic calming devices? Because there is such a high demand (and limited resources) for neighborhood traffic calming, a priority system has been developed by the City's Engineering Division and the Police Department.
Requests are prioritized, based on speeds, volumes, and collision history, and then ranked by severity of the problem. Once a year (typically late September-early October), a list of projects for the coming Fiscal Year - October through September - is selected. If a request does not receive a high ranking (due to the fact that other requested streets have more severe problems), it is possible that the request will not warrant installation of traffic calming devices for several years. If the magnitude of the problem is severe enough so that the request receives a higher priority, the project could be completed in that same Fiscal Year.
Please see the Process Flow Chart for a step-by-step overview of the Neighborhood Traffic Calming Program.
8. What is the role of the Huntsville Police Department (HPD) in this program? Before any petitions are sent out the HPD looks at every request, and makes a determination whether the described problem is one that can be solved with additional enforcement, or through use of a "speed trailer" (a portable trailer with a digital read-out of a driver's speed to "shame" them into driving the speed limit), or would benefit from the installation of traffic calming devices. Typically, streets with very low volumes, but occasional excessive speeds, can have its speeding problem addressed very effectively with speed enforcement. Streets with very high volumes are more problematic to perform speed enforcement, and the sheer numbers of cars make it more cost-effective to use traffic calming devices to enforce the posted speed, rather than requiring enforcement personnel to repeatedly perform enforcement at a problem location.
Finally, the HPD has a permanent representative on the selection committee, to determine the Fiscal Year's traffic calming projects list.
9. What is the role of the Huntsville Fire Department (HFD) in this program? HFD evaluates each street and makes a recommendation on whether or not the street is an Emergency Response Route (ERR). An ERR is a street that serves as the primary route into a neighborhood during an emergency.
If the requested street is an ERR then speed cushions will be installed. If the requested street is not an ERR then asphalt speed tables will be installed.
10. What is meant by "Point of Contact"? The neighborhood Point of Contact is established when the questionnaire form is completed and returned to Engineering. It is usually the resident who has requested the information, but does not necessarily have to be that same person. The Point of Contact is established in order to provide the City with a single point for communications regarding: information about the problem, placement of data collection devices, distribution of petitions, scheduling of neighborhood meetings, and scheduling of the project construction.
11. Does the City of Huntsville require that a petition be signed, in order to install traffic calming devices? Yes, but residents are discouraged from starting this process themselves, for several reasons. First, the request needs to go through Police Department screening, data collection, and the prioritization process, to determine the severity (and thus the approximate time frame for construction- see below). The petition process is initiated only after it has been established that the project is to be completed during the current Fiscal Year.
Second, the petition form itself must be developed by Traffic Engineering Staff and sent to the Point of Contact, complete with all of the addresses that are to be polled in the petition. All residences must be polled for support of traffic calming devices - either "Yes" or "No". Addresses left blank are treated as a "No". A 75% "Yes" vote must be met for traffic calming devices to be installed. Special circumstances will be treated on a case-by-case basis.
Those who were not notified through the petition process (i.e., resident not at home, etc.) must be notified via posted flyers by the Point of Contact. The City will provide the flyers to be posted, which will list the types of traffic calming devices, number and location of devices, installation date, and City contact numbers if there are questions.
12. Do residents who don't live on a street in question, but who use that same street to get to and from their house, get a "vote" in whether traffic calming devices are to be installed on that street? No. People who regularly traverse a street, but don't live on it, are far less likely to vote "Yes" regarding installation of devices that will force them to drive the speed limit. They do not live on the street, and therefore have no motivation to solve the speeding or cut-through traffic problems.
By contrast, people who live on the street in question have to deal with adverse traffic problems 24 hours a day, 7 days a week. They have more of a stake in this process, and they are the ones who must make a decision: whether they are willing to trade personal inconvenience for slower (or less) traffic on their street.
13. Don't speed humps and speed tables slow down the response time for emergency vehicles? Yes. Tests that have been performed by Huntsville's Fire Department and the Engineering Division have shown that speed tables slow down a standard pumper truck (typical first response vehicle) by about 4.5 seconds per table. Therefore, a resident who lives at the end of a street with 7 speed tables can expect an added delay of about 31 seconds.
It should be noted, though, that traffic calming devices do increase the safety of a neighborhood street through the reduction in speeds and volumes, and therefore in collision opportunities (single-car, multi-car, and pedestrian). Depending on the severity of the neighborhood traffic problems, this added safety may actually outweigh the extra response time of emergency vehicles.
14. Why all of this red tape? Since we have a problem, why can't the City just come out and install the devices? Why can't we just circulate a petition, and if everyone on our street wants them, the City will come out and install them? While the City of Huntsville has allocated a dedicated yearly amount of capital funds for Neighborhood Traffic Calming, it is nowhere near the amount required to address every request that comes in.
In the interest of keeping this process as fair and unbiased to all residents city-wide, the City's approach is a "worst first" philosophy: the more severe the problem, the higher the priority. Traffic engineering measurements are made (speeds and number of vehicles per 24 hour period) on every street that requests traffic calming. This evaluation takes time.
Alternatives to this selection process - either selecting the streets by a political process, or selecting on a first-come-first-served basis - don't necessarily solve the worst traffic problems. The process that the City of Huntsville uses may seem bureaucratic and lengthy, but it is a fairer process in the end.