Verification methods and antenna horizontal beamwidth of across-the-road radar for traffic speed enforcement in China

Speed Calibration and Traceability for Train-Borne 24 GHz Continuous-Wave Doppler Radar Sensor

“…The schematic diagram of a train-borne single-channel DRS is shown in Figure 2b, where v is the train speed, ϕ is the design incident angle of train-borne single-channel DRS, and θ is the included acute angle between the direction of train travel and a line from the antenna beam direction of DRS to the rail surface (abbreviated to "included angle" hereafter). The working principle of the train-borne single-channel DRS is similar to that of the vehicle-borne single-channel DRS [10] and traffic radar-based speed meters [18,19], which is also based on the principle of the Doppler effect as expressed by Equation (1):…”

“…Therefore, it has a higher speed-measuring accuracy than the vehicle-borne dual-channel DRS with the Janus configuration. Finally, since the train-borne dual-channel DRS adopts the single-sided asymmetric structure and its two antennas of dual-channel point in the same direction, it can determine the travel direction of the train, depending on whether two Doppler shifts of its dual-channel are positive or negative [18,19].…”

A Vehicular Mobile Standard Instrument for Field Verification of Traffic Speed Meters Based on Dual-Antenna Doppler Radar Sensor

“…Overspeed is a key factor in a high percentage of traffic accidents [ 1 , 2 ], and traffic speed surveillance is an important civilian application to improve road control, law enforcement, and the personal safety of drivers [ 3 , 4 , 5 , 6 , 7 ]. Traffic speed meters are important legal measuring instruments specially used for traffic speed surveillance and enforcement in China and around the world [ 8 , 9 , 10 ]. Until now, there have been four kinds of traffic speed meters legally used in China, i.e., across-the-road (AcTR) radar [ 7 , 8 ], above-the-road (AbTR) radar [ 9 ], dual-beam lidar, and inductive loops [ 10 ], which together with cameras make up overspeed automatic monitoring systems to measure and record a great deal of information of overspeed vehicles for image forensics automatically.…”

“…Traffic speed meters are important legal measuring instruments specially used for traffic speed surveillance and enforcement in China and around the world [ 8 , 9 , 10 ]. Until now, there have been four kinds of traffic speed meters legally used in China, i.e., across-the-road (AcTR) radar [ 7 , 8 ], above-the-road (AbTR) radar [ 9 ], dual-beam lidar, and inductive loops [ 10 ], which together with cameras make up overspeed automatic monitoring systems to measure and record a great deal of information of overspeed vehicles for image forensics automatically. Accordingly, many traditional traffic speed meters, such as hand-held radar and lidar guns (which are still widely used in the United States and many other countries of the world [ 11 ]), which can merely measure and display the speed value of a vehicle without any other information, cannot be used for traffic speed enforcement in China any more.…”

“…Annual verification for traditional traffic speed meters is mainly examined and tested in the laboratory using simulation methods [ 8 , 11 ]. However, most traffic speed meters working together with cameras are fixedly installed on the roadside [ 8 ], above the road [ 9 , 10 ], or under the road [ 10 ], and it is difficult, and even impossible, to disassemble and remove these traffic speed meters from the road to the laboratory for annual verification. Therefore, annual verification for these traffic speed meters must change to be examined and tested in the field by using a vehicular mobile standard speed-measuring instrument (abbreviated to “standard instrument” hereafter) mounted at a test vehicle [ 8 ].…”