The performance of the Sensys wireless vehicle detection system was evaluated under adverse weather conditions (winter and rain) at a signalised intersection and in close proximity to the railroad tracks at a grade crossing. At the intersection stop bar zones, the overall frequency of false calls due to vehicles in the adjacent lanes ranged from 7.7% to 15.4% per lane in the winter data and between 2.6% and 6.2% in the rain data. In addition, the frequency of multiple activations due to a single vehicle (flickering false calls) ranged from 4.2% to 7.2% in the winter data and from 5% to 7.7% in the rain data. There were only seven stuck-on calls, two missed calls, and no dropped calls. At the intersection advance zones, frequency of missed vehicles travelling between the lanes ranged between 0.4% and 5.4% in the winter condition, and between 0.8% and 9.7% in the rain condition. A low percentage of vehicles travelling inside the marked lane (0%-1.2% per lane) were missed. False calls ranged on average from 1% to 4%. No stuck-on calls or dropped calls were found at the advance zones. At the railroad grade crossing, the trains generated multiple activations in the Sensys detectors as they passed the crossing. After they departed, the sensors terminated the activations except in a few cases, where the calls remained stuck-on for periods of time. In addition, false calls were the most common type of detection error, which represented 56% to 60% of the total number of calls in the left-turn lane, and 13% to 14% in the through lane. Most of the false calls in the left-turn lane were caused by vehicles travelling in the opposing direction. (Author/publisher)
Samenvatting