In this way, we selected high resolution video to calibrate the selected parameters. Shown in Figure 6(b), the video was captured in the northern bound of the Xiaozhai intersection gamma secretase activating protein of Xi’an on March 16, 2014. The high resolution camera was set at a footbridge that crosses the intersection approach. The video was recorded at a frame rate of 30f/s from 17:00 to 17:30. The maximum, minimum, mean, and majority values of the longitudinal displacements, horizontal displacements, approaching speed, and heading angle of all the trajectories with the lane changing behavior were summarized in Table 1 and Figure 6(c). Figure
6 Calibration of lane changing behaviors. Table 1 Statistical lane changing behavior parameters. The following steps were taken to capture the vehicle’s trajectories: (1) record the vehicle’s position for every
five frames; (2) obtain the vehicle’s trajectories on ground plane using transmission conversion technology [15]; (3) record all the trajectories and analyze the statistical information of the selected parameters. 4. Cellular Automaton Based Evaluation Method 4.1. Model Construction The cellular automaton is based on discrete time, space, and state. Nagel and Schreckenberg firstly used the cellular automaton, namely, NaSch model [16], to model traffic flow along a road. In NaSch model, space, time, and velocity are discrete. The space is divided into cells with a specific length. Each cell may either be occupied by vehicle or be empty. The integer velocity ranges from 0 to vmax . The unit of the velocity is n integer cells per second. When
a vehicle moves at speed v during time interval t, the moving distance will be v × t. If the time interval t is 1 second, the moving distance will be v, and under this situation v indicates the moving distance in the unit time. Let g represent the gap space between two vehicles in succession. The driver reaction time is taken as one second. For the arbitrary configuration, one update of the system consists of the following four consecutive steps, which are performed in parallel for all vehicles. There are some corrections on the NaSch model to make it get better robustness and reliability [17] on specific traffic environment (such as mixed traffic [18]) or driver behaviors [19]. Although the correction models GSK-3 are different from the NaSch model, they basically follow the four steps of NaSch model. The steps of the model are shown as follows. Determine slow probability Ps before the vehicle state is updated: If Vj,it=0, Then ps=ps0; Else if Vj,it>0, Then ps=ps1, (2) where ps0 > ps1, ps0 is the slow probability for vehicles that follow slow-start rules, and ps1 is the slow probability for vehicles that do not obey slow-start rules. Step 1 . — Acceleration: consider If Vj,it