E 320 Design Vehicle Physical Characteristics and Minimum Clearances

The State of California establishes the required clearances between motor vehicles permitted to use state highways. The Public Utilities Commission sets the clearances required between railroad facilities and motor vehicle structures. 

The discussion that follows is a summary of the regulations as extracted from AASHTO’s A Policy on Geometric Design of Rural Highways, the State’s Planning and Design Manuals, the Motor Vehicle Code, and the Public Utility Commission Pamphlet.

For all projects financed by the State or jointly financed by the City and the State, the City must follow the State’s standards. All other projects done solely under the City’s jurisdiction and financing should follow the State’s standards but may use the City’s standards for clearances. See Subsection E 322.11, Through Roadbeds.

These clearances, the regulations governing the physical characteristics of vehicles, and the relative percentage of the various sized vehicles using the highways must be considered in the design of vehicle storage capacity, structures, pavements (types and thickness), and other highway design elements and facilities.

Relative to the above factors to be used in designing the various street and highway elements, the determination of the types and/or maximum size motor vehicles permitted to use a particular street is generally based on the street classification and local ordinances. Unless specifically posted or where ordinances prohibit their use, major and secondary highways should be designed to carry the maximum legal size motor vehicles.  See Section E 321, Design Vehicle Physical Characteristics. Residentially zoned streets and cul-de-sacs are normally designed to be used only by single unit trucks and busses and by passenger vehicles.