clearly Finally, Section 5 concludes the paper with a summary and discussion about future work.2.?Related WorkIn this section, we summarize the existing more info VDS evaluation systems. Although there are stationary VDS evaluation systems, this paper focuses on portable ones, since most VDSs have already been installed at a stationary Inhibitors,Modulators,Libraries site, so we cannot move them to where the stationary evaluation system is installed. The existing portable VDS Inhibitors,Modulators,Libraries evaluation systems are based on several kinds of detection technologies. The most commonly-used evaluation system utilizes image frame analysis with a camera [13,19]. The video camera is installed at the same place where the VDS to be evaluated is Inhibitors,Modulators,Libraries installed.
When a vehicle passes a known distance as shown in the video, the travel time is measured in frame units.
The number of frames Inhibitors,Modulators,Libraries Inhibitors,Modulators,Libraries per second is used to measure the distance travelled by the vehicle (1 frame = 1/30 s). However, an expert measures the traverse time as an integer number of frames, and that expert must personally evaluate any fractions of frames. It is difficult for different experts (i.e., the video frame analyzers) to measure the fractions of the number of frames consistently and objectively, which adds variability to the results. In addition, image frame analysis tools sometimes experience mechanical failures.Another type of portable evaluation system is based on laser detectors [14]. This evaluation system sends laser light to a reflector, which is stuck to the pavement.
The signal hits the reflector, which reflects it to the evaluation system receiver.
With this transmitter and receiver set, the evaluation Inhibitors,Modulators,Libraries system can detect a passing vehicle. To measure the speed of a vehicle, the evaluation system needs two sets of transmitters and receivers separated by a Inhibitors,Modulators,Libraries known distance. A laser evaluation system can detect the traverse time of a vehicle very accurately without any room for subjectivity. Inhibitors,Modulators,Libraries However, since the evaluation Entinostat system must be AV-951 deployed on the side of the road and the reflector attached to the lane with the VDS to be evaluated, it is easy for any passing vehicle to interfere with the laser signal. In other words, only the traffic of the outer lane can be measured with this system and the measurement of multiple lanes (i.
e., scalability) is very selleck products difficult.The third type of evaluation system is designed with a tape-switch or piezoelectric cable [13].
Passing vehicles press down onto the piezoelectric cable, which creates an electrical impulse. If two piezoelectric cables are separated by a known distance, traffic information including volume count, speed, and occupancy can Binimetinib be measured. Although this type of evaluation system can overcome the drawbacks of video frame detection and can measure traffic information very accurately, the piezoelectric cable is relatively fragile and can be easily broken. It is also difficult for a wired cable system to measure multiple lanes of traffic.