Title: Some Laws of Urban Traffic Dynamics: Analysis, Physical Evidence and Control Applications
1Some Laws of Urban Traffic Dynamics Analysis,
Physical Evidence and Control Applications
Carlos F. Daganzo U.C. Berkeley Center for Future
Urban Transport www.its.berkeley.edu/volvocenter/
2References
- Daganzo, C.F. (1996) The nature of freeway
gridlock and how to prevent it" in Transportation
and Traffic Theory, Proc. 13th Int. Symp. Trans.
Traffic Theory (J.B. Lesort, ed) pp. 629 646,
Pergamon Elsevier, Tarrytown, N.Y. - Daganzo, C.F. (2006) On the variational theory
of traffic flow well-posedness, duality and
applications Networks and Heterogeneous Media
1(4) 601-619. - Daganzo, C.F. (2007) Urban gridlock macroscopic
modeling and mitigation approaches
Transportation Research B 41, 49-62 with
corrigendum Transportation Research Part B 41,
379. - Daganzo, C.F. and Geroliminis, N. (2008) An
analytical approximation for the macroscopic
fundamental diagram of urban traffic
Transportation Research Part B, available on
line. - Geroliminis N., Daganzo C.F. (2007a) Macroscopic
modeling of traffic in cities 86th Annual
Meeting Transportation Research Board, Washington
D.C. - Geroliminis, N. and Daganzo, C.F. (2007b)
Existence of urban-scale macroscopic fundamental
diagrams some experimental findings Working
paper, Volvo Center of Excellence on Future Urban
Transport, Univ. of California, Berkeley, CA
(Transportation Research Part B available on
line).
2
3Definitions
Flow, q VKT / TL (veh/hr) Density, k VHT /
TL (veh/km) Speed, v VKT / VHT
(km/hr) C-rate, f Completions / TL
(veh/km-hr)
(Daganzo, 1996)
4Link Laws
- (q, k, v) related by FD
- q / f d
- Optimal density (Capacity Max C-rate)
(Daganzo, 2007)
5Composition J Identical Links
(Daganzo, 2007)
6Known Result for Ring Roads
- Assume multiple blocks arbitrary block lengths
and widths arbitrary signal settings conserved
vehicles. - Theorem If traffic behaves according to
variational theory, the ring road exhibits a
concave MFD.
7Conjectures
Network of identical links
- Real Networks
- An MFD exists
- Trip completions / Network flow Constant
(Daganzo, 2007)
8San Francisco Simulation No Control
Outflow
Vehicle Accumulation
(Geroliminis Daganzo, 2007a)
9Real World Experiment Site Description
- Fixed sensors
- 500 ultrasonic detectors
- Occupancy and Counts per 5min
- Mobile sensors
- 140 taxis with GPS
- Time and position
- Other relevant data
- (stops, hazard lights, blinkers etc)
- Geometric data
- Road maps
- (detector locations, link lengths, intersection
control, etc.)
10 km2
(Dec. 2001 data)
(Geroliminis Daganzo, 2007b)
10Real World Experiment The Demand
Occupancy by time-of-day
Flow by time-of-day
(Geroliminis Daganzo, 2007b)
11Real World Experiment The Detectors
qi (dimensionless)
oi ()
12Real World Experiment The Detectors
(Geroliminis Daganzo, 2007b)
13Real World ExperimentTaxis
Conjecture Passenger carrying taxis use the same
parts of the network as cars
Then
(Geroliminis Daganzo, 2007b)
14Filters to determine full vs. empty taxis
- A stop is a passenger move, if
- hazard lights are ON or
- parking brake is used or
- left blinker is ON and taxi stops gt 45 sec or
- speed lt 3 km/hr for gt60sec
- A trip is valid if
- trip duration gt 5 min and length gt 1.5 km and
- trip distance lt 2 Euclidean distance
(Geroliminis Daganzo, 2007b)
15Illustration of Filter Results
(Geroliminis Daganzo, 2007b)
16Illustration of Filter Results (Cont.)
(Geroliminis Daganzo, 2007b)
17Real World ExperimentTaxis
Conjecture Passenger carrying taxis use the same
parts of the network as cars
Then
(Geroliminis Daganzo, 2007b)
18Real World Experiment Results
(Geroliminis Daganzo, 2007b)
19Aggregate Dynamics
- Given inflow qin
- Output e G(n)
qin
e G(n)
n
(Daganzo, 2007)
20Finding Effect of Control
No Control
With Control
Trips Ended
Time
Trips Ended
Time
Restrict vehicles from entering
(Geroliminis Daganzo, 2007a)
21Ongoing Work San Francisco
(Daganzo Geroliminis , 2007)