Traffic Signals: Integrating Space & Time … · • AASHTO Bike Guide contains no mention of bike...
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Traffic Signals: Integrating Space & Time Peter Koonce, P.E. City of Portland
Transcript of Traffic Signals: Integrating Space & Time … · • AASHTO Bike Guide contains no mention of bike...
Traffic Signals: Integrating Space & Time
Peter Koonce, P.E.
City of Portland
How can we rethink street and signal
strategies?
• FOLLOW the Policy
What new metrics should we be using?
• Person delay not vehicles
• 2–hour peaks not 15-minutes
• Reliability over excessive speed
• Crashes – which are hard to predict
How do we communicate tradeoffs?
• Are you talking to me?
Policy: Advance Cycling through
Operational Changes
CROW Manual: Design Manual for
Bicycle Traffic
Bicycle Friendly Measures at Traffic Signals
• CROW Manual highlights 16
distinct measures that can be
combined to form safe
intersections
• AASHTO Bike Guide contains
no mention of bike signals
With boxes and signals
Bicycle Boxes
Bicycle Signals
Signal Operations Guiding Principles
Speed & Design
Guiding Principle – Progression Speed
• Shared with traffic (12 to 20 mph)
• Bike lanes/exclusive movement (9 mph)
portland bicycle greenwave
Evaluation of Progression Speeds
Distance
Time
Offset
• Signal timing set to speed limit - 30 mph
• bike traffic “could” get through
without stopping at 22 mph
Cycle Length
Implementation of Progression Speeds
Distance
Time
Offset
• Signal timing set for 19 mph
Cycle Length
Synchro Model of the Pearl District:
NW Everett And Glisan30 MPH
30 MPH
18/22 MPH
Posted Speeds
18/22 MPH
Average Speeds
25 MPH
25 MPH
Night Progression
Speeds
20 MPH
20 MPH
12 MPH
12 MPH
Speeds Before Changes
Speeds After Changes
Guiding Principle:
Bicycle specific design elements
• Types of Signals
• Size of display & location
• Signal timing (details)
Bicycle signals
4 types of signals:
1. Exclusive bicycle phase in
conjunction with other phases
2. Scramble signal
3. Pedestrian-Bike Hybrid Beacon
4. Bicycle indication vs standard
indication
Exclusive bicycle phase
• Lane Configurations:
– 2 thru lanes
– 1 thru/right turn lane
(yield to bikes when
turning)
– 1 bike lane
– 1 right-turn lane
Case Study on Space & Time:
N Broadway & Williams Characteristics
• Prior to bike signal
– Cyclists weave through right turning traffic in the
upstream block to use the bike lane located
between the shared turn and exclusive right-turn
Photo: J. Maus, Bikeportland.org
Exclusivity at Signals
Answer: separate movements with signals
Analysis Results
Period
Dual Right-Turn
Lanes
With Westbound
Bike Phase
Westbound Volume
to Capacity
Westbound Right
Turn Volume to
Capacity
AM 0.69 0.88
PM 0.59 0.80
Thru green
arrows PTR
Bike signal
sign
Advance
Loops
12” yellow
heads on
bike signal
Bike
signal
on
recall
initially
Right turn
arrows
Considering Red
Light Running
Camera
N Broadway & Williams
Signal Features
Use 4” signal
and mount at
cyclists height
Visibility
limited
signal
farside
Best Treatment
Add upstream traffic signal
to increase range of
speeds that can use the
limited green for bicycle
through
Leading Bicycle Interval
Leading bicycle interval
Summary
• Bicycle signals and the details
surrounding them are still under
development
• Time & Space need to be addressed
during design reflecting policy
• Remaining concerns include potential lack
of compliance and liability
Nearside Bicycle Signal
Thank you for your Time
• Peter Koonce, P.E.
• City of Portland
• 503-823-5382
• pkoonce
