ITE Journal - July 2020 - 44

suggest that road user confusion might be possible with this design
approach. In contrast, pedestrian or light rail transit signals use
different shapes and colors that distinguish them from vehicular
signals. While the literature review identified some anecdotal
evidence of road user's confusion (primarily due to lack of
separation between vehicular and bicycle traffic signal faces), none
of the published evaluation reports found evidence of significant
user confusion. Importantly, the review of the literature found
no published studies that directly evaluated visibility or comprehension of the bicycle signal face or the transferability of design
assumptions from motor vehicle users. In other words, questions
such as at what distance can the symbol be seen in various lens
sizes and what movements road users assume as allowable from the
symbol have not been formally researched.

Bicycle Signal Inventory

*  MUTCD Section 4D.07 allows new 8 inch circular signal indications for the "sole purpose of controlling a bikeway
or a bicycle movement" and 9D.02 describes requirements for visibility-limited faces and reviewing timing on
bikeways. No other specific guidance is provided.
**	 IA-16 does require use of the "R10-10b Bicycle Signal" sign.

44

J u ly 2020

ite j o urn al

London, United Kingdom

Lima, Peru

D. Hurwitz, Oregon
State University

The use of green, yellow, and red bicycle symbols in signal faces
(and other traffic control devices) is a widespread practice internationally. Figure 1 shows a small sample of the consistency of bicycle
signal faces. While the symbols are very similar, there is a variation
on other design details. For example, smaller near-side signal faces
are more common elsewhere than the United States. The faces from
Shanghai, China, and Utrecht, Netherlands include an arrow in the
bicycle symbol face indicating the allowed bicycle movement.
In the U.S. context, the bicycle signal housing, backplates,
and mounting practices are similar, and often identical to, motor
vehicle signals. The signal face with the bicycle symbol is often the
only uniquely distinguishing feature.** Human factors principles

S. Kothuri, Portland
State University

Review of Existing Research

A. Clarke, Toole Design Group

The research developed an extensive inventory of bicycle signals.
The locations of bicycle signals were identified by starting with
an existing list maintained by the bicycle technical committee
of the National Committee on Uniform Traffic Control Devices
(NCUTCD). The list was supplemented with responses to an
online survey distributed by the research team to Transportation
Research Board committees and Association of Pedestrian and
Bicycle Professionals (APBP) channels. A total of 511 intersections
were inventoried where the use of the bicycle symbol in the signal
face on at least one approach was verified. For most installations
(86 percent), current Google Streetview images were available
and were the primary source for data collection. Using the
measurement tool in Google Maps and an open-source software to
scale images, the research team collected data for each approach

A. Clarke, Toole Design Group

The first application of a bicycle signal in the United States
is believed to have been in 1994 at the intersection of Russell
Boulevard and Sycamore Lane in Davis, CA, USA.1 Sometime later,
bicycle signals with the bicycle symbol in the face were included in
the 2002 update to the California Traffic Manual and subsequently
adopted in the California Manual on Uniform Traffic Control
Devices (MUTCD).2,3 Nationally, the MUTCD contained provisions
for circular signal indications to control bicycle movements.4* The
2011 NACTO Urban Bikeway Design Guide highlighted the applicability of bike signals, publishing information on their use in 10
American cities and applications in Canada, Europe, and Asia. In
2013, the Federal Highway Administration (FHWA) issued Interim
Approval for Optional Use of a Bicycle Signal Face that allows the
use of bicycle symbols in the signal face with several restrictions.5
The most notable restriction is that the bicycle signal face can only
be used in scenarios where there is no conflicting motor vehicle
movements, which can limit the ability for pratictioners to comply
with the provisions of the IA-16.
Before IA-16, bicycle signals were in use at at more than 40
intersections in a select number of jurisdictions.6 In recognition of
growing use, the National Cooperative Highway Research Program
(NCHRP) funded a research effort to summarize and synthesize the
U.S. experience with bicycle signals using the bicycle symbol in the
face. This updated inventory identified more than 500 intersections
in 61 jurisdictions with a bicycle signal on one or more approaches.
The research also identifed research gaps related explicitly to road
user comprehension and compliance and develop research needs
statements (RNS). The full report can be accessed on the NCHRP
website as Web-Only Document 273.7 The following sections
describe the results of the literature review, an inventory of existing
uses of bicycle signal faces, agency interviews, and identified
research gaps.

Shanghai, China

Utrecht, Netherlands

Figure 1 Examples of International Bicycle Signal Faces.



ITE Journal - July 2020

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