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CMA 2017 #114 · Agenda item attachment · Apr 24 2017
A communication transmitted from Louis A. DePasquale, City Manager, relative to Awaiting Report Item Number 16-95, regarding a report on standardized signage and markings
CITY OF CAMBRIDGE
Traffic, Parking and Transportation
344 Broadway
Cambridge, Massachusetts 02139
www.cambridgema.gov/traffic
Joseph E. Barr, Director
Phone: [phone removed]
Brooke McKenna, Assistant Director
Fax: [phone removed]
MEMORANDUM
To:
Louis DePasquale, City Manager
From:
Joseph E. Barr, Director
Date:
April 20, 2017
Re:
AR-16-95: Report on Standardized Signage and Markings
This memo is in response to Order 9 from the November 7, 2016 City Council Meeting (Awaiting
Report Item 16-95), requesting that the City Manager work with the Traffic, Parking, and
Transportation Department to make street markings and street signage more ubiquitous to market
the rules of the road to the users of all transportation modes and report back on this matter.
The Traffic, Parking, and Transportation Department strives to maintain consistent pavement
markings, signals, and signage standards for traffic operations citywide to provide a safe and
comfortable roadway environment in Cambridge. Using consistent and understandable traffic control
devices is critical to ensure that pedestrians, bicyclists, and drivers understand the rules of the road
and how they are expected to operate in specific conditions. Pavement markings and traffic signs play
an important role in how we manage our streets, and we are continually looking for opportunities to
use these tools most effectively to improve the safety of our transportation system.
For greatest clarity and legibility for users, it is important that our standards are not just consistent
citywide, but also that they are consistent with other cities both across Massachusetts and around
the country. As such, we use Federal and State guidelines to the greatest extent possible so that all
road users recognize and understand the message that is being communicated. Federal standards for
signage and striping are provided in the Manual on Uniform Traffic Control Devices (MUTCD), 2009
Edition. https://mutcd.fhwa.dot.gov/kno_2009r1r2.htm as well as the Massachusetts amendments to
the MUTCD.
In addition to the guidance provided by the MUTCD, newer trends in transportation for bicycle
facilities are guided by the following Federal and State documents:
Page 2 of 4
Massachusetts Department of Transportation (MassDOT) Separated Bike Lane Planning and Design
Guide, 2015
http://www.massdot.state.ma.us/highway/DoingBusinessWithUs/ManualsPublicationsForms/Separa
tedBikeLanePlanningDesignGuide.aspx
National Association of City Transportation Officials (NACTO) Urban Street Design Guide, 2013
http://nacto.org/publication/urban-street-design-guide/
Federal Highway Administration (FHWA) Achieving Multimodal Networks: Applying Flexibility &
Reducing Conflicts, 2016
https://www.fhwa.dot.gov/environment/bicycle_pedestrian/publications/multimodal_networks/
In implementing these traffic controls, we strive to find an appropriate balance in how many signs
and markings we install, trading off issues such as safety, aesthetics, physical space, and many others.
While most traffic control devices such as crosswalks, parking signs, traffic signals, etc. in Cambridge
have been standardized for many years, the evolving state of the practice—particularly for bicycle
facilities—has resulted in many new forms of traffic control. As we work to implement these new
traffic controls, we continue to seek that appropriate balance, communicating key messages without
creating confusion or “sign clutter” that can lead to problems.
Based on our review of the guidance noted above, as well as the input we have received from road
users, we are planning to proactively and strategically incorporate the following traffic control
elements into both upcoming bicycle facility implementation projects and existing facilities through
ongoing maintenance and upgrades:
Green intersection crossing markings
o These markings provide guidance for
cyclists through an intersection while
also alerting both drivers and cyclists to
watch for conflicting movements as they
maneuver through an intersection.
Page 3 of 4
Two stage turn queue box
o These markings provide a designated
location for cyclists to move right at a
signalized intersection and wait for the
cross-street green signal indication. This
allows cyclists to make a left turn without
conflicting with parallel through traffic.
Bike boxes
o Bike boxes provide an advance stop bar
for cyclists at signalized intersections,
allowing them to line up ahead of
parallel vehicular traffic to ensure
visibility and allow for turns during the
green signal phase.
Green shared lane markings
o Green-backed shared lane markings are
installed at key locations where limited
roadway width or other factors require
that bicycles and vehicles share the lane
on short segments connecting between
exclusive bicycle facilities.
Bus stop conflict zones
o Green bike lane markings adjacent to
heavily used MBTA bus stops alert both
cyclists and bus drivers to be aware of
potential conflicts.
Page 4 of 4
Bike signals
o Bike signals are typically implemented at
existing traffic signals as part of the
installation of separated bike lanes along
a corridor. Bike signals may be timed in
several different ways:
Lead bicycle interval: Similar to
and typically concurrent to a lead
pedestrian interval, allowing
bicycles the chance to enter the intersection prior to vehicles to increase
visibility.
Protected bike phase: In locations where heavy turn conflicts or unusual bike
movements exist, signal phasing may provide for protected movements
through either protected vehicle turn phases or exclusive bike phases.
Bike intersection signage
o Turning Traffic Yield to Pedestrians and Bikes – Installed at
locations where turning vehicle conflicts exist
o Except Bikes – Sign placards provide
exceptions for bikes for No Turn on Red
restrictions and one-way/Do Not Enter
restrictions where bicycles may safely
make maneuvers that vehicles are not
permitted to make.
It is important to note that the use of green pavement treatments and shared lane markings is limited
to bicycle intersection features, conflict zones, and key bicycle connections, so as to enhance
conspicuity, compliance, and visibility in these key locations. At this point, we do not intend to paint
entire segments of bicycle lanes green or deploy shared lane markings on the majority of streets,
since such a strategy would reduce the ability to effectively highlight areas of conflict and key
connections.