The Florida Department of Transportation offers the
LOSPLAN 2002 software for free download. This is a sofware package that takes information about a roadway (average daily traffic, lane width, shoulder width, and other parameters) and calculates a
multi-modal level of service--giving an idea of how well this roadway functions for motorists, for bicyclists, for pedestrians, and assigning a letter grade of "A" to "F".
Chicagoland Bicycle Federation Tech Sheet #1: Sidepath Bicycle Facilities is an excellent summary of when bicycle sidepaths (basically, wide sidewalks designated for bicycle and pedestrian use) should be used, when they should be avoided, and how to safely design them. WARNING: The file is a 7MB PDF download.