Construction Guidelines

As part of the process in developing the design guidelines for the Neighborhood Traffic Calming Program, applicable roadway safety criteria from the following design manuals were considered:

  • AASHTO (American Association of State Highway and Transportation Officials) - A Policy on Geometric Design of Highways and Streets
  • Caltrans - Highway Design & Traffic Manuals
  • FHWA (Federal Highways Administration - Manual on Uniform Traffic Control Devices
  • ITE (Institute of Transportation Engineers) Design Criteria
  • ACPWA (Alameda County Public Works Agency) Design Guidelines

The following are construction guidelines for the program:

  1. A step process will be used to apply traffic calming measures in communities.
  2. The device must be located on relatively straight, level roadway sections (i.e. tangents to horizontal and vertical curves)
  3. Proximity to intersections
  4. For speed humps, the roadway must have a gradient of less than five percent (5%) for a minimum of 230 m (750 feet) between intersections in the traffic calming area. Road humps may be used on roadways up to eight percent (8%). The minimum roadway section length may be increased for vehicle control considerations for steep grades adjacent to the roadway section under consideration. The roadway should have a minimum curb to curb or pavement width (unimproved shoulder) of 7.3 m (24 feet) or a maximum of 12.2 m (40 feet).
  5. Roadwasy illumination is required at the traffic calming device
  6. Devices, must be installed entirely within the County's right-of-way
  7. Devices must avoid conflicts with existing infrastructure: utilities, storm-drain facilities including gutter flow, landscaping and driveways
  8. Landscaping ownership and associated maintenance responsibilities must be agreed to by the adjacent property owners
  9. Community financial participation may be required for:
    • right-of-way dedication (if necessary for the traffic calming device)
    • sidewalk, curb, and gutter installation and replacement (if necessary)
    • storm drain/utility relocation landscaping installation and maintenance