Transcript Topic 9 - Ramp Metering

Topic 9
Ramp Metering
CEE 495/771 – Fall 2008
RAMP METERING
Metering Signal
CEE 495/771 – Fall 2008
WHY RAMP METERING


Safety (Breakup Platoon Traffic)
Maintain Freeway Operations 
CEE 495/771 – Fall 2008
FREEWAY FLOW
Volume-Occupancy: All Lanes
10000
Free-Flow Region
Congested Region
9000
8000
Flow, vph
7000
6000
5000
4000
3000
2000
1000
0
0
10
20
30
Occupancy, %
CEE 495/771 – Fall 2008
40
50
60
FREEWAY FLOW
8000
160
7000
140
6000
120
5000
100
4000
80
3000
60
2000
40
1000
20
0
5:00
0
6:00
7:00
8:00
Time
CEE 495/771 – Fall 2008
9:00
10:00
Speed, km/hr
Flow, vph
1-min Moving Average
RAMP METERING CLASSIFICATIONS
Fixed Time
Local
Traffic Responsive
By Operations Level
Coordinated Freeway
Ramp Metering
System Wide
Integrated Freeway/Surface
Arterial Ramp Metering
Single Lane (w/o HOV)
By Geometry
Multiple Lane (w/o HOV)
Ramp Metering
Systems
Entrance Ramp
By Location
Freeway Connector
Mainline Metering
Single Metering
- One Vehicle per Green
By Operations Rule
CEE 495/771 – Fall 2008
Bulk Metering
- > 1 Vehicle per Green
TRAFFIC-RESPONSIVE
RAMP METERING
Mainline Upstream Detectors
Mainline Downstream Detectors
Demand Detector
Merge Detector
Warning Sign/Signal
Metering Signal
Frontage Road
Advanced Queue Detector
CEE 495/771 – Fall 2008
ALINEA Algorithm


Local traffic responsive
Based on feedback control theory
M r (t )  M r (t  1)  K R [ m   (t )]
CEE 495/771 – Fall 2008
COORDINATED FREEWAY
RAMP METERING
CEE 495/771 – Fall 2008
COORDINATED RAMP METERING
SYSTEMS IN THE U.S.
Seattle: 126
Minn-St. Paul: 430
Portland: 110
Milwaukee: 122
Chicago: 117
Salt Lake
City: 23
Denver: 46
N. Virginia: 26
LA: 1478
Phoenix: 122
Arlington: 5
Implemented
In Progress
CEE 495/771 – Fall 2008
New York: 75
COORDINATED RAMP
METERING ALGORITHMS
 BOTTLENECK
Algorithm - Seattle, WA
 ZONE Algorithm - Twin Cities, MN
 HELPER Algorithm - Denver, CO
 SWARM Algorithm - Irvine, CA
CEE 495/771 – Fall 2008