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Michael Sallaberry, PE, Associate Transportation Engineer, San Francisco Department of Parking and Traffic
Contributions by Dustin White, intern, San Francisco Department of Parking and Traffic
Figure 1. Aerial view of path intersection with Masonic Avenue and Fell Street.
A shared-use pathway for bicyclists and pedestrians travels east to west along the Panhandle portion of Golden Gate Park, bordered by a couplet of one-way arterials. Fell Street, the west-bound portion of the couplet, is the closest to the path and to the north. The path travels along the park mostly free of intersections with any roadways except at Masonic Avenue where the path crosses the street in the south crosswalk. The intersection is controlled by a two-phase signal where motorists on Fell Street and people in the east-west crosswalk see a green light and WALK signal at the same time (see figure 1).
There are approximately 300 vehicles per hour turning left from Fell Street to Masonic Avenue in the evening peak hour. That same time is also peak usage for the pathway, which serves as a popular commute route for cyclists. In 2002, 100 cyclists per hour were counted on the path. Given city-wide trends and anecdotal observations, there are likely more cyclists than this today. The number of pedestrians and other wheeled path users contributes to the number of people in the crosswalk at any given time.
Given the popularity of the path, the number of left-turning vehicles traveling across the path, and the number of close calls reported, it has been widely recognized that improvements were needed to ease the potential for conflicts in the crosswalk.
Figure 2. Signage at path crossing.
Figure 3. Aerial view of the intersection with the improvements.
Figure 4. Eastbound view of the crosswalk/path and westbound motorists on Fell Street.
About five years ago, some measures were implemented to improve this area. First, an approximately 3 m (10 ft) long red (no parking) zone approaching the intersection on Fell Street was painted to improve sight lines. Three meters in length was chosen as it was feared that a longer red zone would be routinely violated, as parking demand in the area was high and it may not be clear to motorists why a long red zone was needed. Later on, signs were installed stating LEFT TURN YIELD TO BIKES AND PEDS (figure 2).
Since then, the path was widened and repaved to handle increased demand. As the number of path users continued to climb, so did the number of reported collisions and near-collisions. Another round of improvements to the crossing was warranted.
Though many believed it might be time to have a separate phase for path users and for left turning vehicles, it was recognized that this change would require more time and funding for the needed signal upgrade. Some also thought that perhaps a more moderate, shorter term approach might suffice. In any case, all recognized the need for improvements in the near term. Thus, the next round of improvements included the following:
The proposed red zone improves sightlines between motorists and path users, and is now 18.3 m (60 ft) long, a 15.2 m (50 ft) extension of the existing 3.0 m (10 ft) zone. To improve compliance with this parking restriction, a cross-hatched area was striped in addition to the usual red curb paint and the NO PARKING signs. Speeds on Fell Street are controlled using regularly spaced signals and are 48kph (30mph) during the evening peak period. With a 15.2 m (50 ft) increase to the existing red zone, motorists are able to see people in the crosswalk 1.1 seconds sooner.
The same cross hatching used to emphasize the NO PARKING restriction also discourages motorists from moving closer to the curb as they turn right. A curved extension of the cross-hatching is intended to encourage wider and slower turn movements. Prior to the restriping, many motorists cut the turn with minimal reduction in their speed. The other striping change was to make the crosswalk a ladder-style crossing with a stop bar for northbound Masonic Avenue motorists. These markings were intended to increase the visibility of the crosswalk, and create some space between northbound motorists and the crosswalk. The additional space was intended to allow some margin of safety between path users entering the crosswalk on a stale green and motorists eager to proceed north at their green.
A leading pedestrian interval (LPI) of 3 seconds was also implemented to allow path users to establish themselves in the crosswalk before the platoon of vehicles on Fell Street arrived at the intersection. The LPI also provides a 3 second all-red for the intersection, a secondary benefit. It should be noted that the pedestrian signal is a countdown signal, which displays the amount of time left during the “flashing hand.”
To determine the effectiveness of the changes, a survey was taken of path users. A more scientific approach would have been to observe the intersection and collect data. However, given limited resources and the difficulty of evaluating various levels of conflict and near-collisions between path users and left turning motorists, it was decided that a survey would have to suffice. The survey was taken at various times of the day, mostly on weekdays but also on a Saturday. An effort was made to pick 100 people randomly so that cyclists, pedestrians, and other path user groups would be represented.
Fifty-six percent of path users surveyed did not notice the changes. The 44 percent who did were asked on a 1 to 5 scale what they thought of the changes, 1 meaning “much more safe”, 2 meaning “more safe”, 3 meaning “no change,” 4 meaning “less safe,” and 5 meaning “much less safe.” The average score from this response was 2.3, somewhere between “more safe” and “no change.” More than half of the 42 who responded (two did not) gave a score of 2 (“more safe”) while three respondents replied they felt either “less safe” or “much less safe.”
Anecdotally, some observations have been made. Many motorists are still cutting the turn short, but a higher percentage than before is taking it wider and slower. Northbound motorists on Masonic Avenue obey the stop bar set back 1.5 m (5 ft) from the crosswalk approximately 80–90 percent of the time. Also, there have been very few incidents of motorists parking in the extended red zone. Based on the much higher incidence of motorists parking in the previous 3 m (10 ft)–long red zone, this indicates the crosshatching along the curb makes a difference.
Based on the results of the survey and anecdotal observations, these changes have improved the crossing. However, as noted in the survey results, 56 percent of the respondents did not notice the improvements. The next steps are to consider additional short term improvements and concurrently consider the costs, benefits, and impacts of a separate phase for crosswalk users and left-turning vehicles. As the intersection is already near a volume/capacity ratio of 1.0, there is not much time during a signal cycle to work with. Splitting the phase would yield a significantly shorter crossing time for path users, up to half what it is today. Still, the proposal will be studied in greater detail so that a more informed decision can be made.
It cost approximately $5000 to design and implement the changes and take the survey. The funding was provided by the San Francisco Transportation Authority via Proposition K funds, a fund developed by a half-cent sales tax devoted to transportation improvements within the city and county of San Francisco.
Michael Sallaberry
San Francisco Department of Parking and Traffic
(415) 554-2351
mike.sallaberry@sfgov.org
Dustin White
San Francisco Department of Parking and Traffic
(415) 503-2117
dustin.white@sfgov.org