AGENDA #5d
MEMORANDUM
TO: Mayor and Town Council
FROM: W. Calvin Horton, Town Manager
SUBJECT: Report on Traffic Calming Issues
DATE: January 27, 2003
This report responds to the Council’s request for the following traffic calming information:
1) Suggested policy and procedures for assessing costs of traffic calming measures
2) Differences between speed humps, speed bumps, and speed tables
3) Designs for bicycle-friendly traffic calming devices
4) Can traffic calming devices only be implemented on streets less than 40 feet wide
5) Re-issue the 1998 draft “Policy and Implementation Process for Neighborhood Traffic Management”.
BACKGROUND
During the past 12-18 months, the Council has received a number of requests to install traffic calming devices on public streets in neighborhoods. Offers of neighborhood financial contributions have accompanied some of these requests. At the August 26, 2002 meeting, the Council received a report from the Town Attorney (please see Attachment #1) regarding neighborhood financial contributions to traffic calming projects.
The Council asked the Manager to prepare a report including the following information:
1) Suggested policy and procedures for assessing costs of traffic calming measures
2) Differences between speed humps, speed bumps, and speed tables
3) Designs for bicycle-friendly traffic calming devices
4) Can traffic calming devices only be implemented on streets less than 40 feet wide
5) Re-issue the 1998 draft “Policy and Implementation Process for Neighborhood Traffic Management”.
DISCUSSION
1) Suggested policy and procedures for assessing costs of traffic calming measures:
We have reviewed the Town Attorney’s August 26, 2002 report (Attachment #1) and the existing Town policy for “paving by petition”. If the Council wishes to consider a neighborhood cost-sharing policy, we suggest considering assessments for traffic calming projects in a manner similar to the existing procedures for “paving by petition”. A proposed policy and procedures for assessing costs of traffic calming measures are provided in Attachment #2 for the Council’s consideration. Key procedural points would include:
a) Petition Process: For validation, traffic calming petitions would require signatures of the owners of at least 2/3 of the owners of “benefited properties” and those properties would need to include at least 2/3 of the total street frontage within the “area of land served” by the traffic management measures. The Engineering Department would determine the “area of land served” surrounding the requested project, and properties within that area would be considered “benefited properties” for the purpose of establishing an assessment roll. The petition language would state that owners of benefited properties would be responsible for 50% of the total cost of the improvements.
We recommend that signatures of two-thirds of the identified owners and 2/3 of the front footage be required to validate a petition, rather than a simple majority (51% of the owners and 51% of the front footage) as has been required in the past for street paving petitions. Installation of traffic calming measures may be more controversial than street paving in some neighborhoods and may not improve property values as is typically the case with street paving. We believe that a 2/3’s majority of both owners and front footage would signify strong support for a project.
The size and extent of the area of land served would be based upon the type of traffic calming project being proposed and the specific characteristics of the street network surrounding the proposed project site(s). The petition form would state that the Town Council has the authority to remove the traffic calming devices if necessary, based on the results of follow-up studies and functional evaluations. Thus, it would be possible for residents to be making assessment payments even after the devices have been removed. This is a big difference from the street-paving assessment program.
b) Traffic Studies: Upon receipt of a valid petition, the Engineering Department would gather preliminary data about the request, including traffic volumes, speeds, and accident information. Plan development would consist of the following steps:
· Assessment of problems and needs
· Identification of project goals and objectives
· Identification of evaluation criteria
· Development of alternative plans/solutions
· Selection of a proposed plan
The development of a traffic calming plan would include staff work in conjunction with neighborhood meetings, and a Town Transportation Board meeting. Proposed plans would be based on citizen input and sound engineering principles.
b) Assessment: According to G.S. 160A-218, assessments for street improvements may be made on the basis of:
(1) The frontage abutting on the project, at an equal rate per foot of frontage; or(2) The area of land served, or subject to being served, by the project, at an equal rate per unit of area; or(3) The value added to the land served by the project, or subject to being served by it, being the difference between the appraised value of the land without improvements as shown on the tax records of the county, and the appraised value of the land with improvements according to the appraisal standards and rules adopted by the county at its last revaluation, at an equal rate per dollar of value added; or(4) The number of lots served, or subject to being served, where the project involves extension of an existing system to a residential or commercial subdivision, at an equal rate per lot; or(5) A combination of two or more of these bases. Whenever the basis selected for assessment is either area or value added, the council may provide for the laying out of benefit zones according to the distance of benefited property from the project being undertaken, and may establish differing rates of assessment to apply uniformly throughout each benefit zone. For each project, the council shall endeavor to establish an assessment method from among the bases set out in this section which will most accurately assess each lot or parcel of land according to the benefit conferred upon it by the project. The council's decision as to the method of assessment shall be final and conclusive and not subject to further review or challenge.” Based on the Statute language above, we suggest that, the assessment basis for traffic calming devices be: The area of land served, or subject to being served, by the project, at an equal rate per benefited property. If a project were funded, the Town would install traffic management devices and would pay 50% of the total construction costs. Benefited property owners in the “area of land served” would be assessed on an equal share per lot basis for the other 50% of the project costs. We currently use the per lot basis for street paving assessments also. The owners of assessed property would have the option, within 30 days after the publication of the notice that the assessment roll has been confirmed, of paying the assessment either in a single payment or in not more than 10 annual installments.
d) Monitoring and Follow-up Studies: Town staff would monitor all traffic management measures and would report back to the Council and Transportation Board within 12-18 months regarding the operation and effectiveness of the traffic calming measures. This follow-up report could result in Council action to revise or remove a traffic management measure.
We think that the policy and procedures suggested above would allow pubic involvement at every stage of the project and would provide a reasonable, systematic and equitable means of implementing requested traffic management projects and assessing a portion of the costs to benefited properties.
If the Council desires to proceed with the proposed policy for assessing 50% of the cost of traffic calming devices, we will return with the policy and a resolution of adoption for the Council’s consideration at a future meeting.
2) Differences between Speed Humps, Speed Bumps, and Speed Tables:
Speed Bumps: Bumps are typically steeper and narrower than Humps or Tables. The height of speed bumps varies dramatically, from a few inches to nearly a foot in some cases. Bumps create a sharp “jolt” at low speed. Modern automobile suspensions are designed to absorb such jolts at higher speeds, thus driving over a speed bump at high speed negates its effect. According to the Institute of Transportation Engineers, "Speed bumps (have) been routinely installed on private roadways and parking lots without the benefit of proper engineering studies regarding their design, placement and impact." There are concerns in the traffic engineering community that speed bumps can cause some vehicles to lose traction and control under some circumstances and therefore speed bumps are not recommended for use on public streets.
Speed Humps: Humps are typically flatter and wider than bumps, and consist of raised or “mounded” areas of pavement six or more feet in width and three to four inches in height. Speed humps are often placed in series 300-600 feet apart to create a speed control zone. There is a significant amount of engineering design information available regarding speed humps, and their use is becoming more common throughout the United States. When properly designed and marked, speed humps do not create a problem for drivers traveling at or below the posted speed limit. The jarring reaction of speeding vehicles crossing speed humps will increase as speeds increase.
Speed Tables: Tables are similar to humps, except that speed tables have a flat area rather than a mounded area on top. The flat top area can be of varying widths, with approach ramps on each side of varying steepness depending on the application. Speed tables are typically three to six inches in height, and are often installed as elevated crosswalks or golf cart crossings. Normally, speed tables are more benign than humps or bumps, in that they typically create the least amount of jarring motion when vehicles pass over them due to the dampening effect of the flat top area.
Depending on their design and installation characteristics, speed bumps, speed humps, and speed tables can achieve similar results including:
· Reducing vehicular speeds
· reducing collision frequency and severity
· supplementing police enforcement
· reducing cut-through traffic
Please see Attachment #3 for diagrams of typical speed humps and speed tables.
3) Designs for bicycle-friendly traffic calming devices:
The design of speed humps and speed tables include a gentle slope that allows bicyclists to cross the traffic calming devices safely. Please see the profile sheets of speed hump and table presented in Attachment #3. Also, on streets with designated bike lanes, the speed humps are typically placed only in the motor vehicle travel lanes.
4) Why traffic calming devices are only implemented on streets less than 40 feet wide:
We do not have a specific street width criterion upon which decisions about the installation of calming devices is predicated. Town streets are classified as local, collector, or arterial based primarily on the street’s function rather than its geometry (such as width).
During the development of a traffic calming plan, we consider a variety of factors including traffic volume and speed, street width and grade, on-street parking, proximity of intersections and driveways, etc. We have no specific requirement that traffic calming devices can only be implemented on streets less than 40 feet in width. We evaluate each potential traffic calming installation site individually, typically taking into account a variety of site-specific issues in arriving at our recommendation(s).
5) Re-issue the draft 1998 “Policy and Implementation Process for Neighborhood Traffic Management”:
Attachment #4 is a copy of the draft 1998 document. No Council action has been taken regarding this document.
CONCLUSION
We will be pleased to take further actions as desired by the Council.
ATTACHMENTS
1. August 26, 2002 Town Council Memo on Traffic Calming Assessment (p. 6).
2. Proposed Policy and Procedures for Assessment Process of Traffic Calming Devices (p. 11).
3. Information on Speed Bumps, Speed Humps, and Speed Tables (p. 14).
4. 1998 Policy and Implementation Process for Neighborhood Traffic Management (p. 17).