Civil Engineering Reference Manual for the PE Exam

These paragraphs below deal with parking as it pertains to the mainlanes of a controlled access highway, the frontage roads for such a facility, and parking along urban and suburban arterials. Rest areas as parking facilities are not considered in this article.

Emergency Parking

Parking on and adjacent to the mainlanes of a highway will not be permitted except for emergency situations. It is of paramount importance, however, that provision be made for emergency parking. Shoulders of adequate design provide for this required parking space.

Curb Parking

In general, curb parking on urban/suburban arterial streets and frontage roads
should be discouraged. Where speed is low and the traffic volumes are well below capacity, curb parking may be permitted. However, at higher speeds and during periods of heavy traffic movement, curb parking is incompatible with arterial street service and desirably should not be permitted. Curb parking reduces capacity and interferes with free flow of adjacent traffic.

Elimination of curb parking can increase the capacity of four-to-six lane arterials by 50 to 60 percent. If curb parking is used on urban/suburban arterials or frontage roads under the conditions stated above, the following design requirements should be met:

• provide parking lanes only at locations where needed
• parallel parking preferred
• confine parking lanes to outer side of street or frontage road
• require that parking lane widths be 10 feet [3.0 meters]
• restrict parking a minimum of 20 feet [6 meters] back from the radius of the intersection to allow for sight distance, turning clearance and, if desired, a short right turn lane.