traffic signals: integrating space & time … · • aashto bike guide contains no mention of...

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

• peter.koonce@portlandoregon.gov

• pkoonce