AGENDA #5i

 

MEMORANDUM

 

TO:                  Mayor and Town Council

 

FROM:            W. Calvin Horton, Town Manager

 

SUBJECT:       Report on Portable Speed Humps

 

DATE:             May 10, 2004

 

 

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

 

BACKGROUND AND DISCUSSION

 

At its April 26, 2004 meeting, the Town Council asked for information on portable speed humps. The following information was previously submitted to the Council at its January 27, 2003 meeting.

 

Town staff researched the issue and found that several communities are using portable speed humps, mainly for temporary installations.  Attachment 1 provides several photographs of different types of portable speed humps. 

 

Portable speed humps, also known as “speed cushions”, 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.  Portable speed humps are used mainly for temporary installations where the hump is expected to be removed or replaced with a permanent hump. 

 

Advantages:

·        Typically reduces vehicle speeds in the vicinity of hump.

·        Can reduce vehicular volumes under some circumstances.

·        Relatively easy to remove, if necessary.

·        Emergency response times may not be affected to the extent they are with traditional humps.

·        Gaps can be provided between segments that allow cyclists to pass without significant difficulty.

 

Disadvantages: 

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

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

 

The Manual on Uniform Traffic Control Devices (MUTCD) and Federal Highway Administration (FHWA) provide guidance on the appropriate design and use of portable speed humps or other portable traffic management devices on public streets.  Our research indicates that the cost of installing a portable speed hump varies from $3,000 to $6,000, including materials, depending on the street width.  Maintenance costs vary depending on the location of the portable hump installation, the condition of the underlying street, and the traffic characteristics.  

 

The City of Fayetteville experimented with portable speed humps on public streets and found that the portable units were difficult to install securely in some instances and often loosened and became displaced under traffic volumes and speeds typically found on public streets, thus requiring significant levels of inspection and maintenance.

 

Some communities in North Carolina, Florida, California, and Georgia have installed portable speed humps on public streets in residential areas; however, they are more commonly used with some success on private commercial/institutional driveways and parking lot drive aisles where traffic speeds and volumes are low.

 

CONCLUSION

 

Portable speed humps could be installed on low-volume/low-speed public streets in residential areas in Chapel Hill.   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. 

ATTACHMENTS

 

1.                  Photographs of Portable Speed Humps (p. 3).