The Federal Highway Administration (FHWA) has now finalized a trimmed-down list of design criteria for roads on the National Highway System (NHS) in a change that will simplify many projects and give more design flexibility to state and local governments.
Instead of the 13 design criteria it had applied to all NHS roads since 1985, the FHWA said it will now apply just 10 criteria to design of high-speed roads like interstate highways and other major routes. For low-speed NHS routes, such as urban roads or rural roads that become main streets through smaller cities, it will require designers to use just two criteria.
In doing so, the FHWA said its revisions "help reduce cost and speed up the design of roads and streets located in smaller towns and cities … [and] allow state and local engineers to develop flexible design solutions that meet local travel needs and goals."
In a Register notice last October, the FHWA had proposed eliminating three criteria – bridge width, vertical alignment and lateral offset to obstruction – from its list of controlling design criteria. It also proposed renaming three others.
After reviewing public comments, the FHWA said the result is that it will apply 10 controlling criteria to the design of "high-speed" roads on the NHS for traffic operating at 50 mph or faster. Those criteria are design speed, lane width, shoulder width, horizontal curve radius, super-elevation rate, stopping sight distance, maximum grade, cross slope, vertical clearance and design loading structural capacity.
On "low-speed," non-freeway NHS roads designed for traffic below 50 mph, the FHWA will now require only the criteria of design speed and design loading structural capacity.
