The U.S Federal Highway Administration (FHWA) published a memorandum endorsing “a flexible approach to bicycle and pedestrian facility design.”

The memorandum published last August 20 reminds FHWA administrators that the American Association of State Highway and Transportation Officials (AASHTO) bicycle and pedestrian design guides contain the flexibility to also incorporate the guidance published in the National Association of City Transportation Officials (NACTO) Urban Bikeway Design Guide and the Institute of Transportation Engineers (ITE) Designing Urban Walkable Thoroughfares.

Design guides from AASHTO are holy writ for American road engineers. The AASHTO “Green Book”– so-called because of the cover color — in particular is required for use when designing streets and roads that are part of U.S. National Highway System. These are Interstate Freeways, principal routes connecting to them, and roads important to strategic defense. These streets and roads comprise about 14 percent of all federal-aid roadway miles in California, and about 4 percent of all roadway miles Sidewalks and bikeways adjacent to roads that are part of the National Highway System must also adhere to FHWA design rules.

In spite of their limited applicability, many local authorities follow the lead of the federal highway agency and apply these standards for the national system at the local level. Hence, although 10 foot roads are fine for local roads, we often see stroads with 12 to 14 foot lanes.

Local jurisdictions follow the AASHTO guide, state design guides such as the California Highway Design Manual (HDM) or design guidance from organizations such as the ITE out of liability concerns. Neither federal nor (in California) state law mandates adoption or adherence to these guides. Municipalities often adopt them to protect themselves from lawsuits. FMany don’t have the resources to develop their own standards and practices, so they adopt those in the AASHTO Green Book, the HDM, or another previously adopted manual, or those of other cities.

California cities may adopt or modify their own standards that deviate from the AASHTO Green Book and the HDM. If these changes generally fall within the range of acceptable practice allowed by other nationally recognized design standards, the adopting agencies are protected from liability to the same extent they would be if they applied the Green Book or a state guide.

There’s a lot of excitement among cycling advocates about the impact this FWHA memorandum will have on the Federal system, but perhaps it will lead to changes at the local level as well.

Read the FHWA memorandum on Bicycle and Pedestrian Facility Design Flexibility here.