Roadway Design Manual and Code Amendments

To: Mayor McCaa and City Council Members
From: Cochise Bicycle Advocates
Date: January 12, 2004
The Cochise Bicycle Advocates, a local organization promoting safe bicycling and achieving a bicycle-friendly community, submits the following comments on the proposed Sierra Vista Modified Maricopa County Roadway Design Manual:

Section 4.1.5 DEVELOPMENT OF PLANS AND SPECIFICATIONS, of the Roadway Design Manual states that project design and construction, unless otherwise indicated, shall be in accordance with provisions of specified publications, including, the Guide for the Development of Bicycle Facilities, as distributed by AASHTO.
Bicycle Lane Width
The Roadway Design Manual Table 5.1, Lane Widths, states a preferred bike lane width with curb and gutter (edge line to gutter joint) of 6 feet and minimum width of 3 feet. The preferred bike lane width without curb and gutter is 6 feet and minimum width is 4 feet.
The AASHTO Guide for the Development of Bicycle Facilities, Section 8.2.9, Bicycle Lanes, states the minimum bicycle lane width on curbed roadways where parking is prohibited is 4.5 feet from the edge of the vehicle lane to the joint between the roadway and gutter pan. When the gutter pan is less than 12 inches wide, the minimum distance from the vehicle lane to the face of the curb shall be 6 feet. The minimum bicycle lane width on non-curbed streets with no parking is 6 feet. There is no mention of a minimum width of 3 feet for bike lanes on streets with curb and gutter or 4 feet for bike lanes on non-curbed streets.

Shared Use Paths Design
Roadway Design Manual Section 8.3.2 SHARED USE PATH WIDTH AND CLEARANCE DISTANCES
Paragraph B states “A minimum two-foot-wide stabilized surface area shall be provided adjacent to both sides of pathway pavements. This area shall remain free from obstructions and serve as a two-foot clear zone and be included within the designated right-of-way.”
The clear zones serve as shoulders that would permit path users who inadvertently step or bicycle off the path to easily return to the path and would allow users to move off the path if they wish to stop, without blocking other users.
Constructing clear zones as stated above on future shared use paths will provide a needed safety feature missing on most of the City’s existing paths. On many existing paths, the asphalt pavement is placed on the soil base with no soil even with the pavement surface, forming drop-offs of about 4 inches at the pavement edges. Along some paths, soil erosion adjacent to the edge of the pavement has created deeper drop-offs, some more than a foot deep. Several paths have steep downward slopes of loose soil, loose gravel, rip-rap, or cemented rip-rap adjacent to the edge of the path pavement, constituting serious hazards of injuries for path users who inadvertently step or bicycle off the pavement.