Bicycle Signal Heads
Prepared by Timothy Bustos, Bicycle and Pedestrian Coordinator, City of Davis, California with contributions by Dave Pelz, former Public Works Director, City of Davis, California (retired), and Jonathon Flecker, former Traffic Engineer, City of Davis (now in private practice).
The City of Davis, California, has been a mecca for bicycling since the mid-1960s. Bicycling accounts for over 19 percent of the mode share in Davis; nationally, 2 to 3 percent is considered high. Whenever possible, grade separations (underpasses and overpasses) have been built to minimize conflicts between bicyclists and motorists crossing arterial streets. Where grade separations have not been possible, specially designed traffic control devices have been added at selected intersections.
Bicyclists cross on a green signal in Davis.
To help manage the large number of bicyclists utilizing the city's transportation network, there has been an ongoing need to explore new engineering techniques that benefit bicyclists and enhance safety for all road users. The use of bicycle signal heads was chosen as one such approach in 1996, inspired by the use of bicycle signals in the Netherlands. The goal was to enhance safety for bicyclists while maintaining adequate levels of service for motor vehicles at each of the intersections where these signals were installed.
At the time, bicycle signals were used widely in other countries, such as China, England, and the Netherlands. However, bicycle signal heads never had been approved for use in the United States, so the city was required to go through an approval process that included an experimental, conditional-use phase for the bicycle signal heads, with final approval to be granted by the California Traffic Control Devices Committee (CTCDC) under the purview of the state DOT, Caltrans.
Potential intersections that were evaluated for retrofitting with bicycle signal heads were selected based on three primary criteria: 1) volume of bicyclists at peak hour(s), 2) bicycle and motor vehicle crash data, and 3) proximity to schools (primary, secondary, and university).
A red bicycle signal heads in Davis.
Other locations considered for bicycle signal placement were those where separated bike paths connected with intersections in such a way that conventional traffic light configurations could not be seen by bicyclists. These were typically locations where there was a three-way intersection for motorists (i.e., T-intersections) that became four-way intersections for bicyclists.
Bicycle signal heads are similar to conventional traffic signals. However, rather than red, yellow and green "balls," the signal heads use red, yellow, and green bike icons. These lights are actuated in the same way as traditional traffic lights: through the use of bicycle sensitive loop detectors and, where appropriate, bike push buttons.
The traffic light tells motorists to stop, and the bicycle signal head tells bicyclists to cross.
Although several locations throughout the city met the criteria listed above, the location that would ultimately prove the viability of bicycle signal heads was the intersection of Sycamore Lane and Russell Boulevard. This location is a T-intersection for cars, yet it is a "five-way" intersection for bicyclists due to the presence of bike lanes and bike paths that converge at this location. It is also a primary access point to UC Davis for many of the students and employees in the northwest quadrant of the city. Manual traffic counts at this location indicated that approximately 1,100 bicyclists and 2,300 motor vehicles were passing through this intersection during peak hours. Additionally, this would be the first location where both motorists and bicyclists could see the conventional traffic lights and the bicycle signal heads.
Previously, all bicyclists, pedestrians, and motor vehicles would proceed through this intersection concurrently, with many bicyclists and pedestrians choosing the routes they perceived to be the most direct, which were not necessarily the safest. Bicycle signal heads were chosen for this location to help make the movements of different road users more predictable, and thereby safer. To this end, movements were split, with bicyclists and pedestrians moving through the intersection first and motor vehicles proceeding only after all the bicyclists and pedestrians had cleared the intersection. Additionally, a changeable message sign was added for the motorists, indicating NO RIGHT TURN ON RED to prevent through bicyclists from being hit by right-turning motorists.
Evaluation and Results
To objectively assess how effective the bicycle signal heads were in reducing conflicts, surveys were conducted with both motorists and bicyclists before and after the addition of bicycle signal heads. Additionally, video footage was taken of bicycle, pedestrian, and motor vehicle movements before and after intersection modification. Bicycle and motor vehicle crash reports were also evaluated before and after the installation of the bicycle signal heads.
Both motorists and bicyclists found the new signal heads to be effective in reducing conflicts between the various modes passing through the intersection. Evaluation of crash data seemed to reflect this as well. For the two-year period before the installation of bicycle signal heads at the intersection of Sycamore and Russell, there were about 16 bicycle and motor vehicle collisions. For the two-year period following the installation, there were only two collisions, neither of which involved bicycles.
Conclusions and Recommendations
This study demonstrated that:
- Bicycle signals enhance safety by separating large volumes of bicycle and auto traffic,
- There is minimal additional delay to motor vehicles,
- Bike signals are easy to comprehend by bicyclists and motorists, and
- Bicycle traffic signals should be considered on a case-by-case basis, taking into account intersection geometry and bicycle and motor vehicle volumes.
As a result of what the City of Davis was able to demonstrate regarding the effectiveness of bicycle signal heads, CTCDC voted to approve use of this traffic control device in 1998. Subsequently, the California legislature amended the California Vehicle Code to allow its use statewide, and it was signed into law by the governor in 1999.
At present, bicycle signals can be found in bicycle-friendly cities such as Austin, Texas, and Madison, Wisconsin, as well as throughout California and Oregon. In late 2013, bicycle signal heads gained interim approval from the FHWA for inclusion in the MUTCD.
Costs and Funding
Cost will depend on the complexity and size of the intersection, but in general, installation and maintenance costs are comparable to the installation of conventional traffic signals (e.g., controller boxes, detection devices, mast arms, etc.).
Bicycle and Pedestrian Coordinator for the City of Davis, CA