ITE Journal - July 2020 - 47

needed additional research. The interviews suggest that agency
practice guided many of the decisions on lens size. For example,
New York City, NY uses almost exclusively 8-inch lenses and had
175 intersections in the sample. About 40 percent of the agencies
reported that they were using visibility restricting devices to shield
the bicycle signal face from the view of persons driving and were
using or plan to use 4-inch bicycle signal heads.
While most agencies reported following the guidance set by
IA-16, a majority (57 percent) of the agencies stated that the IA-16's
requirement of limiting bike signals to scenarios where there is no
conflicting motor vehicle movements had limited their ability to use
bicycle signals. One agency stated that research on the relative need
or safety benefit of this requirement is critical, citing long delays
that result to all users when only movements without conflicts are
required. Some agencies have interpreted the guidance to limit
the use of leading bike intervals (LBIs) and there are current RTEs
to implement them. Other RTEs are active for applications with
conflicting movements that do not comply with IA-16. A number
of agencies indicated that they found the IA-16 requirement of
providing at least 3 ft. of separation between bicycle and motor
vehicle signal heads to be challenging to implement on existing poles.
While not the focus of the interview, a need was expressed for
improved guidance and research on current practices for yellow
change and red clearance intervals and determining if longer
intervals increase safety and tradeoffs associated with signal timing
and phasing strategies for bicycles (i.e., exclusive phasing, LBI,
delayed turn).

when needed for safety or operations. This study documented an
increasing number of installations of bicycle signals in a wide range
of U.S. jurisdictions, especially after Interim Approval 16 was issued
in 2013. A wide range of applications were identified, including
use on two-way bicycle facilities, locations with heavy vehicle
turning traffic (either left or right), connecting bicycle facilities
to shared-use paths, contra-flow bicycle lanes, left-turns, and
others. The interviews with agencies identified positive results and
challenges with implementing IA-16 in some situations. The effort
suggests more research is warranted on bicycle signal faces, bicycle
symbols, and the appropriate traffic control design for permissive
movements by bicyclists. itej

Research Gaps Identified

1.	 Pelz, D., T. Bustos, and J. Flecker, J. The Use of Bicycle Signal Heads at
Signalized Intersections. Davis California. 1996.
2.	 California Department of Transportation. California Traffic Manual. 2002
update. 1996.
3.	 California Department of Transportation. California MUTCD. 2006.
4.	 FHWA. 2009. Manual on Uniform Traffic Control Devices.
5.	 FHWA. 2013. Interim Approval for Optional Use of a Bicycle Signal Face (IA16). https://mutcd.fhwa.dot.gov/resources/interim_approval/ia16/
6.	 Monsere, C., Figliozzi, M., Thompson, S., Paulsen, K. Operational Guidance
for Bicycle-Specific Traffic Signals in the United States. Final Report, Oregon
DOT and Oregon Transportation Research and Education Consortium,
SPR 747. 2013.
7.	 Monsere. C, Hurwitz, D., Fink, C., Kothuri, S., Schultheiss, B., Hillman, T.,
Shaw, G., Boudart, J., Cobb, D. Road User Understanding of Bicycle Signal
Faces on Traffic Signals. NCHRP Web-Only Document 273. 2020. http://
onlinepubs.trb.org/onlinepubs/nchrp/nchrp_wod_273.pdf (Accessed
June 3, 2020).
8.	 Monsere, Chris. Road User Understanding of Bicycle Signal Faces on
Traffic Signals. http://web.cecs.pdx.edu/~monserec/bicycle_signals.htm
(Accessed June 3, 2020).

A synthesis of the results from the literature review, inventory, and
interviews identified three research needs about the road user's
understanding of bicycle symbols in the signal face. In priority
order, the research needs identified were:
ƒ	 Optimal methods to communicate allowable,
protected, or permissive movements to bicyclists at
signalized intersections.
ƒ	 Evaluation of size, placement, and orientation of bicycle
signal faces on bicyclist and driver comprehension
and compliance.
ƒ	 Guidance on visibility and detection of bicycle symbols in
signal faces by lens size and distance.
Full text of NCHRP research needs statements were drafted
and are being submitted to the relevant AASHTO committees for
consideration in the research funding cycle.

Conclusion
Bicycle signals are an useful tool for controlling the movements of
bicycles in unique situations and for separating bicycle movements

Acknowledgment
The research presented in this paper is based on work supported by
the National Cooperative Highway Research Program (NCHRP)
under Project 20-07 Task 420. Any opinions, findings, conclusions,
or recommendations expressed in this material are those of the
authors and do not necessarily reflect the views of the NCHRP. Bill
Schultheiss, P.E. (M), Jesse Boudart, Thomas Hillman, and Gwen
Shaw (M) at Toole Design Group contributed to the research. Duong
Vu at Portland State University and Alden Sova, Logan Scott-Deeter
(S), Jason Formanack, and Lukas Bauer at Oregon State University
contributed to data collection. Rock Miller, P.E., PTOE (F) shared
his initial list prepared by the NCUTCD bicycle technical committee
that was instrumental in developing the list of intersections.

References

w w w .i t e.or g

J u ly 2020

47


http://www.dot.ca.gov/hq/traffops/engineering/ctcdc/exp/90-7BicycleSignalHeadsStudy.pdf http://www.dot.ca.gov/hq/traffops/engineering/ctcdc/exp/90-7BicycleSignalHeadsStudy.pdf https://mutcd.fhwa.dot.gov/resources/interim_approval/ia16/ http://onlinepubs.trb.org/onlinepubs/nchrp/nchrp_wod_273.pdf http://onlinepubs.trb.org/onlinepubs/nchrp/nchrp_wod_273.pdf http://web.cecs.pdx.edu/~monserec/bicycle_signals.htm http://www.ite.org

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