Deploying Wireless Vehicle Detection System
with SCATS Adaptive Control
Implementation
SCATS is deployed using inductive loops in two configurations with similar results. Loop installations are commonly installed using either a 2 m by 4.5 m long loop or two closely spaced 1.75 m by 1.75 m loops per lane.
Deploying WVDS within SCATS is very similar to the two loop configuration. The first sensor is located near the first loop wire vehicles would cross. The second sensor is located approximately 0.5 m before the last loop lead-in wire a vehicle would cross while departing the detection area. This is shown in Figure 1.
To insure a consistent single detection area, a detection extension is added to the output of Sensor Y. Table 1 below illustrates the amount of extension needed for this sensor, based on the design speed.
Fast Installation
Installation of each Sensys wireless sensor takes less than 10 minutes. Installation simply requires boring a 10cm diameter hole approximately 5.7 cm deep at the desired sensing location, placing the sensor into the hole so that it is properly aligned with the direction of traffic, and sealing the hole with fast-drying epoxy. No lead-in cabling or long saw cuts are required, and the circular pavement hole produces little damage and stress to the roadway.
The sensors communicate with the Sensys Networks Access Point (AP). The AP can communicate with up to 48 sensors simultaneously. The AP is typically mounted on the pole nearest the traffic control cabinet. The recommended minimum mounting height for the AP is 6 meters. When the AP is mounted at this height, it can communicate with sensors up to 45 meters away.
System Management
WVDS offers an agency the unique ability to actively and automatically manage their detection system using Sensys Networks SNAPS software or the System Manager (SSM) appliance. SNAPS/SSM are server based applications which enable the user to:
- Remotely monitor the WVDS systems
- Remotely diagnose and configure the WVDS systems
- Automatically collect and store detection data for analysis
SNAPS/SSM automatically collects key operational parameters of the WVDS including RF signal strengths and link quality, battery levels and individual sensor-to-sensor comparisons. When a deviation from the acceptable levels are measured, a diagnostic alarm can be sent to the maintaining agency, arming it with the information required to take pro-active measures to insure a very high level of detector availability. A color coded map can be populated to provide a fast and easy system health reference as shown below.
SNAPS and SSM enable remote management all the WVDS systems connected to the Traffic Management Center (TMC) via Ethernet or cellular modem. Additional tools implemented include the ability to remotely configure, manage and operate each individual system just as if you were present at the location. As Sensys Networks enhances the firmware of the system, SNAPS/SSM can remotely upgrade the entire sensor network.
SNAPS/SSM collects and archives every detection event for data analysis and diagnostics. SNAPS collects and stores this information indefinitely, while SSM will store the last 90 days of data.
Application noteDeploying Sensys Networks Wireless Vehicle Detection System with SCATS Adaptive Control (PDF)