Vehicle Detectors
Vehicle detectors are an integral part of these modern traffic control systems. The types
of traffic flow data, as well as their reliability, consistency, accuracy, and precision, and
the detector response time are some of the critical parameters to be evaluated when
choosing a vehicle detector. These attributes become even more important as the number
of detectors proliferate and the real-time control aspects of ITS put a premium on the
quantity and quality of traffic flow data, as well as the ease of data interpretation and
integration into the existing traffic control system.
Current vehicle detection is based predominantly on inductive loop detectors (ILDs)
installed in the roadway subsurface. When properly installed and maintained, they can
provide real-time data and a historical database against which to compare and evaluate
more advanced detector systems. Alternative detector technologies being developed
provide direct measurement of a wider variety of traffic parameters, such as density
(vehicles per mile per lane), travel time, and vehicle turning movement. These advanced
detectors supply more accurate data, parameters that are not directly measured with
previous instruments, inputs to area-wide surveillance and control of signalized
intersections and freeways, and support of motorist information services. Furthermore,
many of the advanced detector systems can be installed and maintained without
disrupting traffic flow. The less obtrusive buried detectors will continue to find
applications in the future, as for example, where aesthetic concerns are dominant or
procedures are in place to monitor and repair malfunctioning units on a daily basis.
(Vehicle Detector Technologies for Traffic Management Applications -Part 1
Lawrence A. Klein – Consultant)
Table 1. Detectors Used During Field Tests
Symbol
Technology
Manufacturer
Model
Output Data
U-1
Ultrasonic
Doppler
Sumitomo
SDU-200 (RDU101)
Count, speed
U-2
Ultrasonic
Presence
Sumitomo
SDU-300
Count,
presence
U-3
Ultrasonic
Presence
Microwave Sensors
TC-30C
Count,
presence
M-1
Microwave
Detector,
Motion,
Medium
Beamwidth
Microwave Sensors
TC-20
Count
M-2
Microwave
Detector,
Motion,
Medium
Beamwidth
Microwave Sensors
TC-26
Count, speed
binning
M-4a
Microwave
Detector,
Motion,
Narrow
Beamwidth
Whelen
TDN-30
Count, speed
M-5
Microwave
Detector,
Motion,
Wide Beamwidth
Whelen
TDW-10
Count, speed
M-6
Microwave
Radar,
Narrow
Beamwidth
Electronic
Integrated Systems
RTMS-X1
Count,
presence
speed,
occupancy
IR-1
Active IR,
Laser Radar
Schwartz
Electro-Optics
780D1000
(Autosense I)
Count,
presence,
speed
IR-2
Passive IR
Presence
Eltec
842
Count,
presence
IR-3
Passive IR
Pulse Output
Eltec
833
Count
IR-4 b
Imaging IR
Grumman
Traffic Sensor
Presence,
speed
VIP-1
Video Image
Processor
Econolite
AUTOSCOPE
2003
d
VIP-2
Video Image
Processor
Computer
Recognition
Systems
Traffic Analysis
System
d
VIP-3 e
Video Image
Processor
Traficon
CCATS -VIP 2
d
VIP-4b
Video Image
Processor
Sumitomo
IDET-100
d
VIP-5 c
Video Image
Processor
EVA
2000
d
A-1f
Passive Acoustic
Array
AT&T
SmartSonic
TSS-1
Count
MA-1
Magnetometer
Midian
Electronics
Self Powered
Vehicle Detector
Count,
presence
L-1 b
Microloop
3M
701
Count,
presence
T-1b
Tube-Type
Vehicle
Counter
Timemark
Delta 1
Count
a M-3 was designated for a microwave radar detector that was not received.
b Used at Tucson Arizona test site only.
c Used in Phoenix Arizona 7/94 test only.
d Count, presence, occupancy, speed, classification based on length. Some
provide headway, density, and alarm functions.
e Used at all Arizona test sites.
f Used in Phoenix 11/93 and Tucson tests.