Highway 401 is a long freeway in Ontario (828 km) connecting the border of Ontario-Quebec to Windsor-Detroit. A part of Highway 401 that crosses the City of Toronto is one of North America’s busiest roadways, resulting in extensive congestion during rush hours. The Ministry of Transportation of Ontario (MTO) monitors volume, speed, and travel times of Highway 401 segments regularly throughout the day. MTO also posts the travel time information during the peak periods on the selected overhead Variable Message Signs (VMS) installed at the key locations of the highway. SMATS deployed its TrafficXHubTM sensors on Highway 401 in a pilot project with MTO and CIMA+ (a consulting firm) to test the sensors' performance in terms of detection rate resulting in travel time data sample size.
Current Technology Approaches
Bluetooth travel time sensors, that detect Discoverable Bluetooth devices have been an industry standard with a detection rate between 2% and 5% of the traffic. Declining detection rates of these sensors have been the main concern of traffic practitioners. In the past few years, the number of on-board electronic devices, operating in Bluetooth Discoverable mode, has been getting lower and the detection rate has been dropping over time. The low detection rates can result in a statistically unreliable data sample for travel time measurement and estimation of an origin-destination matrix. Declining detection rates becomes more problematic, especially when the variance of travel time increases.
SMATS TrafficXHub™ is a pole-mount sensor that can detect Bluetooth Classic (in Discoverable and Connected modes), Bluetooth Low Energy, and Wi-Fi signals.
Four TrafficXHub™ sensors were installed on Highway 401 in Toronto, Ontario in the summer of 2019. Data was collected for three days. The TrafficXHub™ was used to target Bluetooth Connected, Bluetooth Low Energy, Wi-Fi, and Bluetooth Discoverable devices in passing traffic. The sensors were connected to the SMATS iNode™ data analytics cloud application through cellular communication using the sensors’ onboard LTE modem. Encrypted identifiers were matched, and outlier data points were filtered on iNode™ to obtain accurate travel time data. The loop detector data were used to measure the ground-truth traffic volume to verify the sensor’s detection rate. The detection rate of the TrafficXHub™ senor was measured based on the number of unique identifiers matched and filtered for each signal type divided by the actual traffic counts.
Sensor's and link locations on the iNode™ map
Sensor's status page on iNode™
SMATS delivered the following test results:
- iNode™ successfully filtered outliers and captured abrupt changes to the travel time during this period. The links travel time graphs and histograms were illustrated on iNode™.
iNode™ link analysis (travel time and speed) charts
- The Wi-Fi detection rate was 8.10% and the Bluetooth Discoverable, Connected, and Low Energy mode detection rates were recorded as 4.7%, 21%, and 32.7% respectively. These results clearly indicate that the sample size associated with Bluetooth Discoverable mode was the lowest and relying only on this as the sole source of data can potentially result in statistically unreliable data.
- For optimal performance, Bluetooth Connected and Bluetooth Low Energy were run simultaneously to deliver the 53.7% capture rate, far exceeding Wi-Fi and Bluetooth Discoverable modes.
TrafficXHub™ sensor detection rates
TrafficXHubTM provides innovation in ITS, ensuring travelers get accurate travel time information.