A common complaint made about the 2009 Manual on Uniform Traffic Control Devices (MUTCD) is that it provides insufficient guidance about effective lateral placement of shared lane markings (aka sharrows) and bike lanes, resulting in some DOTs installing sharrows on the right side of narrow lanes (below) or placing bike lanes and sharrows in the door zone of parallel parking.
Bicyclist safety advocates often describe frustration when traffic engineers defend such installations by claiming compliance with the minimum requirements of the MUTCD. The ITE Traffic Control Devices Handbook, 2nd Edition (2013), however, provides much more effective and detailed guidance for installation of bicycle-specific traffic control devices including shared lane markings. Advocates and engineers looking for an authoritative justification for exceeding the minimum specifications of MUTCD (and explaining why those minimums are insufficient) will find Chapter 14 the Handbook very helpful. For instance, see this paragraph on bicyclist positioning:
“The bicyclist’s lateral position should clearly indicate to following motorists whether passing is encouraged. To support this, some agencies increase the minimum right-side offset of the Shared Lane Marking when used in narrow lanes; for example, Florida DOT uses 5.5. ft. (1.7 m) for lanes narrower than 13 ft (4.0 m). Another approach is to center the marking in a lane that is too narrow to share. This clearly indicates a bicyclist is allowed full use of a narrow lane, and is likely to produce more consistent overtaking behavior, encouraging full lane changes into the adjacent travel lane on a multi-lane street, or crossing the centerline when an adequate gap is obtained on a street with only one lane in the bicyclist’s direction.”
The ITE Traffic Control Devices Handbook provides specific guidance on Sharrow placement for different lane widths in Table 14-4:
Table 14-5 in the Handbook shows how the door zone of on-street parkig reduces usable lane width, and where to locate sharrows in the center of this usable lane width:
Additional excerpts from the ITE Traffic Control Devices Handbook can be seen here and here. Every traffic engineering department should have a copy of this book. Pointing traffic engineers and planners to the guidance and detailed explanations it provides is an effective way that advocates can improve the quality of facility implementation in their communities.