ATTACHMENT 4

MEMORANDUM

TO:                 Mayor and Town Council

FROM :           W.  Calvin Horton, Town Manager

SUBJECT:       Report on Portable Speed Humps

DATE:             January 27, 2003

The purpose of this report is to provide information on portable speed humps.

BACKGROUND AND DISCUSSION

We have been asked for information on portable speed humps. Town staff researched the issue and found that several communities are using portable speed humps, mainly for temporary installations.  Attachment #1 provides a photograph of a portable speed hump. 

Portable speed humps, also known as “rubber speed humps”, are typically formed from recycled rubber in 4 foot to 8 foot wide sections bolted to steel connector plates and anchored onto the roadway using lag bolts.  The size and markings are similar to those of permanent asphalt humps.  Portable speed humps are used mainly for temporary installations where the hump is expected to be removed and/or replaced with a permanent hump. 

Advantages:

· Typically reduces vehicle speeds in vicinity of hump

· Can reduce vehicular volumes under some circumstances

· Relatively easy to remove, if necessary

Disadvantages:

· Increased potential for Town liability issues if portable speed humps are installed and not regularly inspected and maintained.

· Relatively high unit cost (2-3 times cost of comparable asphalt unit)

· Requires frequent maintenance/repair (should be inspected daily to determine if units are becoming loose and/or dislocated)

The Manual on Uniform Traffic Control Devices (MUTCD) and Federal Highway Administration (FHWA) provide clear guidance on the appropriate design and use of portable speed humps or other portable traffic management devices on public streets.  However, our research shows that the cost of installing a portable speed hump varies from $3,000 to $6,000, depending on the street width.   Typically, humps are installed in sets of two and at multiple locations on a long street.  Installation of portable speed humps would obligate the Town to inspect and maintain them for proper function on a much more frequent basis than is necessary with asphalt speed humps.

In his previous position with the City of Fayetteville, NC, our Traffic Engineer experimented with portable speed humps on public streets.  He found that the portable units were difficult to install securely and often loosened and became displaced, thus requiring significant levels of inspection and maintenance.  In one case, a displaced portable hump caused a driver to lose control of the vehicle resulting in an accident.  Subsequently, Fayetteville discontinued the installation of portable speed humps on public streets.    

CONCLUSION

Due to the high installation costs and significant maintenance obligations associated with portable speed humps, and with no clear guidance from the MUTCD and FHWA regarding their use, we do not believe that portable speed humps provide a practical alternative to standard asphalt humps at this time.

We will consider adding portable speed humps to our palette of traffic calming devices for future consideration depending on further research and recommendations in the Manual on Uniform Traffic Control Devices and from the Federal Highway Administration.

ATTACHMENTS

1. Photograph of Portable Speed Hump (p. 17).

PORTABLE SPEED HUMP