26-04-2012, 03:19 PM
A Wireless Sensor Network for Smart Roadbeds and Intelligent Transportation Systems
[attachment=20894]
Introduction
The congestion level on our nation’s roadways is spiraling out of control. The
Texas Transportation Institute estimates that the total cost of congestion to
commuters in 1997 was $72 billion, or $750 per commuter. [Schrank99, V-13]
The amount of congestion-induced delay experienced by the average commuter
in a large city such as Los Angeles or Boston has more than doubled since 1982.
[Schrank99, III-9]
Traffic Sensor Technology
Approaches
Traffic sensor systems can be classified into two types. The first type uses
sensors, placed at many points throughout the road network, that count and
measure the speed of passing vehicles. This data can be used to intelligently
control traffic signals, and can be used with a simple queuing model to predict
link times on the road network. The second type of system aims to measure link
times directly, by tracking the progress of probe vehicles through the road
network.
Systems that use Probe Vehicles
Another type of traffic sensor system aims to measure travel times directly,
using probe vehicles. In one project, workers placed GPS tracking devices on a
small subset of vehicles in a metropolitan area. By monitoring the progress of
the instrumented vehicles through the road network, past link times could be
measured, from which future link times could be extrapolated. Unfortunately, this
approach requires a statistically significant number of vehicles be instrumented
with GPS tracking devices, which is a daunting undertaking.
Traffic Sensor System Design Goals
We wanted to design a system that would allow easy, inexpensive
monitoring of traffic flow statistics and environmental conditions on every major
road. The sensors would have to be small, extremely robust, easily manageable,
and installable at a low cost. The system would have to be capable of returning
data for processing in near real time.
[attachment=20894]
Introduction
The congestion level on our nation’s roadways is spiraling out of control. The
Texas Transportation Institute estimates that the total cost of congestion to
commuters in 1997 was $72 billion, or $750 per commuter. [Schrank99, V-13]
The amount of congestion-induced delay experienced by the average commuter
in a large city such as Los Angeles or Boston has more than doubled since 1982.
[Schrank99, III-9]
Traffic Sensor Technology
Approaches
Traffic sensor systems can be classified into two types. The first type uses
sensors, placed at many points throughout the road network, that count and
measure the speed of passing vehicles. This data can be used to intelligently
control traffic signals, and can be used with a simple queuing model to predict
link times on the road network. The second type of system aims to measure link
times directly, by tracking the progress of probe vehicles through the road
network.
Systems that use Probe Vehicles
Another type of traffic sensor system aims to measure travel times directly,
using probe vehicles. In one project, workers placed GPS tracking devices on a
small subset of vehicles in a metropolitan area. By monitoring the progress of
the instrumented vehicles through the road network, past link times could be
measured, from which future link times could be extrapolated. Unfortunately, this
approach requires a statistically significant number of vehicles be instrumented
with GPS tracking devices, which is a daunting undertaking.
Traffic Sensor System Design Goals
We wanted to design a system that would allow easy, inexpensive
monitoring of traffic flow statistics and environmental conditions on every major
road. The sensors would have to be small, extremely robust, easily manageable,
and installable at a low cost. The system would have to be capable of returning
data for processing in near real time.