Evaluation of Shared Lane Markings
508 Captions
Figure 1. Illustration. Specifications for the sharrow from California MUTCD 2010. The figure shows the technical drawing specifications for the sharrow, which is 111 inches tall and 39 inches wide. The drawing shows two upward-facing chevrons above a bicycle facing left. Dimensions are shown for each part of the bicycle and the chevrons.
Figure 2. Photo. Bike-in-house marking. The photograph shows the original bike-in-house shared lane marking. The symbol is depicted on a street in white paint. It shows a person riding a bicycle going toward the left. The bicyclist is inside a hollow arrow pointing upward.
Figure 3. Photo. Bike-and-chevron marking. This photograph shows the bike-and-chevron shared lane marking. The symbol is depicted on a street in white paint. It shows a bicycle facing left with two upward-facing chevrons above the bicycle.
Figure 4. Illustration. Generic version of a sharrow. This figure was taken from the 2009 Manual on Uniform Traffic Control Devices (MUTCD) and shows an illustration of a generic sharrow. The entire sharrow is 112 inches tall and 40 inches wide. The sharrow is white on a gray background. It consists of a bicycle facing left with two upward-facing chevrons above it. The bicycle portion of the sharrow is 72 inches tall.
Figure 5. Photo. Massachusetts Avenue in the before condition. This photograph shows Massachusetts Avenue in Cambridge, MA, in the before sharrow condition. There are two travel lanes in each direction, motor vehicle parking on both sides of the street, and a narrow raised median in the center. There are stores lining both sides of the street, and motor vehicles are parked on both sides.
Figure 6. Illustration. Cross section view of Massachusetts Avenue before and after sharrow installation. This figure has two parts: The top drawing shows the cross section of Massachusetts Avenue in Cambridge, MA, in the before sharrow condition, including, from left to right, a 21-ft spacing from the curb to the travel lane line, an 11-ft spacing from the travel lane line to the raised concrete median, a 5-ft-wide concrete median, an 11-ft spacing from the concrete median to the travel lane line on the other side of the street, and a 21-ft spacing to the curb on the other side of the street. There are areas designated for parked motor vehicles on both sides of the street. The bottom drawing shows the same cross section but in the after sharrow condition. The street has the same dimensions; however, there is one sharrow 10 ft from the curb on both sides of the street. The sharrows appear next to the parked motor vehicles.
Figure 7. Photo. Bicyclist riding over the sharrows. This photograph shows a bicyclist riding over the shared lane marking on Massachusetts Avenue, which is a two-way road with two travel lanes in each direction, motor vehicle parking on both sides of the street, and a narrow raised median in the center. The bicyclist is riding forward on the street next to parked motor vehicles. Traffic is approaching the bicyclist from behind.
Figure 8. Photo. Potential dooring event. This photograph shows a motorist opening the door of a parked car as a bicyclist is approaching from behind on Massachusetts Avenue. There is a line of parked motor vehicles in front of and behind the motorist opening the door. Additionally, there are motor vehicles driving in the lane next to the parked motor vehicles.
Figure 9. Graph. Speed data in Cambridge, MA. This figure shows two histograms of speed data for Massachusetts Avenue in Cambridge, MA. The top bar graph shows speed in the before period, and the bottom bar graph shows speed in the after period. Frequency is on the y-axis from zero to 60 in increments of 20. Speed is on the x-axis in miles per hour from zero to 45 mi/h in increments of 5 mi/h. The top graph is right skewed with the peak between 25 and 30 mi/h, and the bottom graph is like a modal distribution with one peak around 23 mi/h and another peak around 30 mi/h.
Figure 10. Photo. Operating space for a bicyclist in the after period. This photograph shows a bicyclist riding over the shared lane marking next to parked motor vehicles on Massachusetts Avenue in Cambridge, MA. The bicyclist is riding forward, and passing motorists to the bicyclist's left are allowing operating space for the bicyclist.
Figure 11. Photo. Outbound view of MLK Boulevard. This photograph shows Martin Luther King Jr. (MLK) Boulevard in Chapel Hill, NC. The figure shows a street with two travel lanes in each direction and a two-way left-turn lane in the center. There is no on-street parking. The photo is taken from the top of a small hill, and the street has a downgrade that ends at a signal-controlled intersection. Motor vehicles are traveling in both directions on the street, and traffic on the cross street of the intersection is stopped at the light.
Figure 12. Illustration. Cross section view of MLK Boulevard before and after sharrow installation. This figure has two parts. The top diagram shows a drawing of the cross section of Martin Luther King Jr. (MLK) Boulevard in Chapel Hill, NC, in the before sharrow condition, including, from left to right, a 15-ft spacing from the curb to the outside travel lane line, an 11-ft spacing from the outside travel lane line to a two-way, left-turn lane line, a 12-ft center two-way left-turn lane, an 11-ft spacing from the center two-way left-turn lane line to the outside travel lane line on the other side of the street, and a 15-ft spacing to the curb on the other side of the street. The 15-ft sections include a 2-ft gutter pan. The bottom drawing shows the same cross section in the after sharrow condition. The street has the same dimensions; however, there is one sharrow 43.5 inches from the curb on each side of the street.
Figure 13. Photo. Motor vehicle passing a bicycle after sharrow placement with traffic in the adjacent lane. This photograph shows a bicyclist riding forward on Martin Luther King Jr. (MLK) Boulevard in Chapel Hill, NC, approaching a sharrow. A motor vehicle is passing the bicyclist in the outside lane with traffic in the adjacent lane in the outbound (downhill) direction.
Figure 14. Photo. Bicyclists riding over the sharrow in the outbound (downhill) direction. This photograph shows two bicyclists, one behind the other, riding over a sharrow in the outbound (downhill) direction on Martin Luther King Jr. (MLK) Boulevard in Chapel Hill, NC. There is a motor vehicle approaching the bicyclists from behind.
Figure 15. Photo. Bicyclist riding next to the sharrow in the inbound (uphill) direction. This photograph shows a bicyclist riding between the sharrow and the curb in the inbound (uphill) direction on Martin Luther King Jr. (MLK) Boulevard in Chapel Hill, NC. There are passing motor vehicles in the lane next to the bicyclist.
Figure 16. Photo. Motor vehicle position in the uphill direction after the sharrow. This photograph shows the typical position of a motor vehicle to the left of the sharrow in the outside lane in the uphill direction on Martin Luther King Jr. (MLK) Boulevard in Chapel Hill, NC. The motor vehicle is passing the sharrow without driving over it. There is traffic following this motor vehicle.
Figure 17. Photo. Bicyclist interaction with motor vehicle at driveway. This photograph shows a bicyclist riding forward on a sidewalk and passing a driveway as a motor vehicle is turning right into the driveway off of Martin Luther King Jr. (MLK) Boulevard in Chapel Hill, NC.
Figure 18. Photo. Fremont Street in the before condition. This photograph shows Fremont Street in Seattle, WA, in the before sharrow condition. The street has two travel lanes in each direction and parking on both sides of the street.
Figure 19. Illustration. Cross section view of Fremont Street before and after sharrow installation. This figure has three parts. The top drawing shows the cross section of Fremont Street in Seattle, WA, in the before sharrow condition which includes a 20-ft spacing from the curb to the center line on both sides of the street. There are two parked motor vehicles on the left side of the street and one on the right. The second drawing shows the same street in the after period 1 condition which includes, from left to right, a 17.5-ft spacing from the curb to the center line in the downhill direction, a 10.5-ft spacing from the center line to the edge of the bicycle lane in the uphill direction, a 5-ft bicycle lane with an image of a bicycle, and a 7-ft spacing from the edge of the bicycle lane to the curb on the other side of the street with a parked motor vehicle in the space. The third drawing shows the same street in the after period 2 condition, which includes the same dimensions as in the after period 1 condition but with a sharrow placed on the street in the downhill direction The sharrow is 12.25 ft from the curb.
Figure 20. Photo. Typical position of bicyclist after sharrow installation. This photograph shows the typical position of a bicyclist riding next to a parked car in the downhill direction on Fremont Street in Seattle, WA, after the sharrows were installed. The bicyclist is riding forward next to the parked motor vehicles with passing motor vehicles approaching from behind.
Figure 21. Photo. Potential dooring in before period. This photograph shows a motorist opening the door of a parked motor vehicle as a bicyclist is passing in the center of the downhill lane on Fremont Street in Seattle, WA, in the before sharrow condition. There is ample space between the bicyclist and the motor vehicle to avoid a dooring event.
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