HomeMy WebLinkAboutShared Lane Markings Sharrows Discussion_12
Commission Memorandum
REPORT TO: Honorable Mayor and City Commission
FROM: Rick Hixson, City Engineer
Craig Woolard, Director of Public Works SUBJECT: Shared Lane Markings (Sharrows) Policy Discussion
AGENDA ITEM TYPE: Discussion, Direction
MEETING DATE: September 8, 2014
SYNOPSIS: The 2009 Downtown Bozeman Improvement Plan made a number of
recommendations for improving the character of the Downtown Business District, among which
were recommendations for streetscape improvements to Mendenhall Street. In addition, the Downtown Bozeman Partnership, Bozeman Area Bicycle Advisory Board (BABAB) and Pedestrian and Traffic Safety Committee (PTSC) have been encouraging the City's engineering
division to take advantage of every opportunity to enhance non-motorized facilities, not only
downtown but throughout the City. One such opportunity has recently presented itself, and in
conjunction with our partners we would like to take advantage of it. As you know we recently performed a complete mill and overlay of Mendenhall Street. This presents us with a "blank canvas" for pavement markings. We have re-established the centerline, turn markings and
crosswalks already, but we would like to use this opportunity to add shared lane markings, most
often referred to as "sharrows" to this street. Based on our research and the recommendations of
the Western Transportation Institute and BABAB, we have concluded that the proper location for these sharrows is in the center of each of the travel lanes. Because this constitutes a significant change to an important downtown street and will set a precedent for future installations, we are
requesting formal direction from the Commission on the installation of sharrows on Mendenhall
Street and the use of shared lane markings on existing streets.
RECOMMENDATION: Staff recommends installation of sharrows in the center of each travel lane on Mendenhall Street and to use sharrows on existing streets that are identified as bike
routes where dedicated bike lanes cannot be accommodated.
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BACKGROUND: We began planning for the re-striping of Mendenhall in early 2013. On
February 1, 2013 ALTA Planning and Design Group provided a concept memorandum to the
Downtown Bozeman Partnership which described some potential bicycle improvements for
Mendenhall. One of their suggestions was to narrow the travel lanes sufficiently to allow striping of a dedicated bicycle lane to the south of the south vehicle lane. Engineering staff made detailed
measurements of the street and prepared a memorandum summarizing the effects of adding a
dedicated bike lane. A copy of that memo is attached. The conclusion of that investigation was
that without removing parking on one side of Mendenhall a bike lane could not safely be added,
even with drive lanes reduced to the minimum allowable width. Neither engineering staff nor the Downtown Bozeman Partnership support removal of on-street parking on Mendenhall.
As an alternative to dedicated bike lanes, we were asked to consider adding sharrows to the
street. We agreed that this was an idea whose time had come, an idea which would clearly
indicate increasing support of incorporating bicycles into the mainstream of the city's transportation infrastructure. Furthermore, we had already added sharrows to a number of lower
volume streets such as Black Avenue. We reached out to the Western Transportation Institute
(WTI) at Montana State University (MSU) for guidance on the precise location of the sharrows.
We also researched the National Association of City Transportation Officials (NACTO) Urban
Bikeway Design Guide as well as the Manual on Uniform Traffic Control Devices (MUTCD) about the best location for sharrows. The conclusion we reached based on input from all of the
above was that the markings should be placed in the center of the travel lanes. From the NACTO
Guide: "On streets with posted 25 mph speeds or slower, preferred placement is in the center of
the travel lane to minimize wear and encourage bicyclists to occupy the full travel lane". This
placement also conforms to the requirements of Montana Code Annotated chapter 61-8-605 (2)(c) which governs bicycles on the public roadways:
"(2) A person operating a bicycle upon a roadway at less than the normal speed of traffic at the
time and place and under the conditions then existing shall ride as near to the right side of the
roadway as practicable except when: (c) necessary to avoid a condition that makes it unsafe to continue along the right side of the roadway, including but not limited to a fixed or moving
object, parked or moving vehicle, pedestrian, animal, surface hazard, or a lane that is too narrow
for a bicycle and another vehicle to travel safely side by side within the lane [emphasis added].
The italicized portion of the citation is precisely the situation we have on Mendenhall Street. Riders who attempt to ride next to vehicles on their right or left respectively will find themselves
in the door zone of parked vehicles. Cars which try shy away from riders next to them may find
themselves being crowded to the other edge of the road. Given this situation we feel that the
exception to riding as far to the right as possible applies and that the proper location for the
sharrows is in the center of the travel lanes.
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Striping Master Plan In addition to the specific request for Commission direction on the use of sharrows on
Mendenhall Street, we are also seeking broad policy guidance on the use of shared use markings
on other roadways within the City. Commission guidance at this point is important because we are in the process of updating the City’s transportation master plan and preparing a city-wide
bike and pedestrian striping plan. Both plans will incorporate bike transportation as an important
component of managing traffic demand in Bozeman.
UNRESOLVED ISSUES: None.
FISCAL EFFECTS: These striping costs were anticipated and have been included in the
annual street renovations budget. The estimated cost of the markings is $5,000.00 for installation
and they are anticipated to last three years.
ALTERNATIVES: As suggested by the City Commission.
Attachments: Mendenhall Street Suitability for Bike Lane Memo
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Mendenhall Street Suitability for Bike Lane
The Bozeman Area Transportation Plan recommends bike lanes be designated on Mendenhall
Street from N. 11th Ave to Wallace Ave. The plan notes that this may require removal of parking or lane configuration changes.
Required lane widths
Mendenhall Street is designated as a minor arterial (Bozeman Area Transportation Plan). The standard lane widths for minor arterial streets are shown in figure 9-15. Vehicle travel lanes are shown to be 11 feet wide. An emergency parking/bike lane is shown to be 8 feet wide (from face
of curb). Bike lanes are shown to be 5 feet wide.
There is a note on Figure 9-15 that states “MDT routes will need to meet MDT Urban Design Standards which may not be represented in this graphic”. Mendenhall Street is an MDT Urban Route from Rouse Avenue to 11th Avenue. For on-street parking, the MDT standard is 10-foot
wide parking lanes, measured from the edge of traveled way to face of curb (Design Manual
11.2.5.3). For typical curbed urban streets, a 2-foot shoulder is also standard, so the edge of the
traveled way would be 12 feet from face of curb (Figure 11.70, Design Manual). For Urban Minor Arterials, the standard travel lane width is 11 feet, and the lane width does not include the
gutter section (Figure 12-8, Design Manual).
The AASHTO Guide for Bicycle Facilities recommends that bike lanes be a minimum of 5 feet
wide when on street parking is allowed on a curbed street. A minimum of 13 feet from face of curb to outside edge of the bike lane striping is recommended where there is substantial parking
or turnover of parked cars is high. This allows for an 8-foot parking lane. Parking demand is high
on Mendenhall especially from Wallace to 5th.
Required back of curb to back of curb (BC-BC) width to designate a bike lane on the one-way portion of Mendenhall while maintaining parking as it currently exists is 52 feet per MDT standards and 44 feet per City of Bozeman standards. To install bike lanes on the two-way
portion of Mendenhall, while maintaining parking as it currently exists, the minimum dimensions
would be 57 feet per MDT standards and 49 feet per City of Bozeman standards.
Existing street widths For the two-way portion of Mendenhall from Rouse to Wallace, the BC-BC width is
approximately 41 feet (Range: 41.00 to 40.75). Parking is allowed on both sides of the street
currently. The one-way portion of Mendenhall is variable in width, ranging from 37 to 44.36 feet (BC-BC) where parking is allowed on both sides. The curb bulbs at Willson narrow the width to about 29 feet, and the bus island between Black and Tracy narrows the street to 26.71
feet. The attached plan sheet shows street dimensions at various locations along Mendenhall.
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Traffic volume and characteristics
Traffic volumes range from approximately 4,700 to 5,300 vehicles per day on Mendenhall from Rouse to 7th. Approximately 1.8% of the vehicles are classified as commercial vehicles. Truck
widths are typically 8 to 8.5 feet, with 8.5 feet being the maximum allowed without a special
permit. This does not include mirrors. The typical mirror to mirror width for trucks and buses is
typically 10.5 feet, whereas for sport utility vehicles the mirror to mirror width is 8 feet.
Streamline buses are 10 feet wide mirror to mirror. Typically there are over 60 Streamline bus
trips per day on portions of Mendenhall from Rouse to 7th.
Recommendation
In order to designate bike lanes on Mendenhall Street, parking would have to be removed from
one side of the street in order to meet minimum lane widths. Reducing vehicle lane and/or
parking lane widths to accommodate bike lanes may be unsafe, as bikes will be crowded into the
door zones of parked vehicles and large commercial vehicles will invariably encroach into the
bike lane or other traffic lanes at times.
The Florida Department of Transportation did an extensive study1 to examine the influence of
lane width on the safety of transit vehicles. The results of the study indicate that narrow lane
widths, especially lane widths of 10 feet and narrower are overrepresented in the occurrences of
bus sideswipe crashes. The report recommends that 12-foot wide lanes be provided as practical as possible for roadways located on transit routes.
The narrowed street sections of Mendenhall at Willson and between Tracy and Black will be a
problem for bike lane designation, even if parking is removed in other areas. A bike lane would
reduce the vehicle travel lanes to 10.5 feet at Willson, and would reduce the vehicle travel lanes to approximately 9 feet between Tracy and Black. Turning movements at Willson, which are
already difficult for large vehicles, will become more problematic if bike lanes are designated.
It is recommended that unless parking can be removed from one side of Mendenhall, and street
widening is done at Willson and between Tracy and Black, that bike lanes should not be
designated. ______________________________________________________________________________
1 Integrating Transit into Complete Streets Design Policies, Florida Department of Transportation, June 2010
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