Thinking Inside the Box
Peter Koonce, P.E.
City of Portland
Presentation Outline
Call to Action
Highway Capacity Manual Construct for Data Collection
In the Loop History
Why We’re Here Today
Traffic signals are a big part
of the work that we do
Need to Improve
– Management
– Traffic Monitoring
and Data Collection
HCM Capacity Definition
Capacity, c (lower case) depends fundamentally on
– the saturation flow rate, s, of the lane
- Saturation flow rate assumes the maximum rate of flow
that can pass through the lane group under prevailing
traffic and roadway conditions (expressed in units of
vehicles per hour of effective green)
– green per cycle is g/C:
- Where g is the green time for a movement and C (capital
C) is the cycle length
- g/c is the effective green per cycle (expressed as a
percentage)
c = s (g/C)
2.1.3
HCM Capacity Analysis Calculation
The volume-to-capacity ratio (v/c) is given the
symbol X in intersection analysis:
X = (v/c) = vC/sg
• Sustainable values of X range from 0.0
to 1.0
• The critical v/c ratio, Xc, is an
intersection measure considering only
lane groups with the highest flow ratio
for each signal phase
Xc =
(v /s ) [C/(C-L)]
i
i
i
where i is the various movement or “phase”
2.1.3
HCM Capacity Analysis
Considering the control of a signalized intersection over
time you can start to consider how much time is associated
with each traffic flow
1
5
2
6
3
4
7
8
Time
2.1.3
Use of Loops for Counting
•
•
•
•
Vehicle Counts from a single long loop or multiple loops in a
single lane
Vehicle Classification and Speed
Vehicle Tracking
Loop Diagnostics
Source: Reno A&E
Translating Data into Information
What would additional data do?
Enhanced response to customers
Reduced liability
Prioritizing our efforts
What should the information be?
Effective performance measures should be applicable to the
users, easy to calculate, accurate, and clearly and
consistently interpreted
Sample MOEs from NWS Voyage
Signal controllers have
the ability to collect
information
– Phase service Y/N
– Ped service Y/N
– Average Green
11
Number of pedestrian calls
Assists in signal retiming
– Helps in knowing potential for a pedestrian resulting in longer side
street demand
– Identifies periods of high demand
Performance Measures for a Phase
Measure volume +
Measure green time
Identify where split
adjustments are helpful
Source: Day, C., E. Smaglik, D.M. Bullock, and J.
Sturdevant, ” Cycle Length Performance Measures:
Revisiting and Extending Fundamentals,” Paper ID:
TRB 09-0061, in press.
1.0
Volume/capacity
Yields an estimate
of capacity
0.0
0:00
12:00
24:00
Preemption and Priority Reports
Preemption
– Rail
– Emergency Vehicle
Priority
– Bus Operations
– Other Modes
Integration of Detection and Controller
Recent research at Purdue University has linked detector
activity with controller information
The Purdue Coordination Diagram (PCD) collects
– arrival time of each vehicle at an intersection
– information about the phase state (red and green intervals)
24-Hour Plot of Intersection Saturation
• 1,2 | 3,4
• Virtually no
slack Capacity
1.2
Intersection Saturation
1.0
1234
1278
5634
5678
20 pt. Mov. Avg.
0.8
1
9
2
#
3
>
4
"
0.6
6
$
5
:
7
=
8
!
0.4
• 5,6 | 3,4
• Extra Capacity,
opportunity to reduce
C
0.2
0.0
0:00
2:00
4:00
6:00
8:00
10:00
12:00
14:00
16:00
18:00
20:00
22:00
0:00
Time of Day
Source: Day, C., E. Smaglik, D.M. Bullock, and J. Sturdevant, ” Cycle Length Performance Measures:
Revisiting and Extending Fundamentals,” Paper ID: TRB 09-0061, in press.
16
In the Loop
What it is
– … The inclusion of a specific traffic controller
software in a simulation or model.
Why Is it Done
– Improve Accuracy
– Test advanced features
– Reduce uncertainty
HIL Set-up
Example
SW Moody/SW Porter Transit/Auto intersection
– Anticipation of 24 preemption calls
- Requirement of lead-in/lead-out phases
– Uses all 16 signal channels to accommodate the various modes
-
Cars – 1500+ PM Peak by 2035
LRT & SC – 40 movements by 2035
Bus – 40-50 PM Peak by 2035
Peds & Bikes 300-700 PM Peak by 2035
– Will be one of the most unique intersections in Portland
- Mistakes at the design phase will be expensive to fix later
- Or will cost operating time at the intersection
SW Moody/Porter Rail Movements
SW Moody/Porter Under Construction
SW Moody/Porter
Using HIL we were able to
– Test & refine signaling plans
- Additional intersection clearance time
- Checkouts to prevent track fouling
- Understanding how the intersection will recover
– Understand the likely operation of the intersection
- Using VISSIM we modeled the intersection using a COP 2070
controller to understand how the installed equipment will function
Questions
Thanks for participating
Peter Koonce, P.E.
Principal Engineer
[email protected]
@pkoonce