Specifications

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A typical velocity profile of a vehicle that comes to a complete stop at an intersection is shown
in Figure 5.3. Given the standard camera–intersection configuration, most vehicles are already
decelerating when entering the system’s field of view. However, it is typical for vehicles that
come to a complete stop to exhibit a second stage of much more rapid deceleration as they
approach the stop sign. Coming to a complete stop at any of the studied intersections is a rare
event. It is estimated based on the video analysis that less than 20% of the vehicles stop
completely. However, the accuracy of this estimate is difficult to judge given that the video
analysis is susceptible to some false alarms and missed or incomplete vehicle tracks.
Figure 5.3. Velocity profile of a vehicle coming to a complete stop
A typical velocity profile of a vehicle that fails to come to a complete stop at an intersection is
shown in Figure 5.4. While the majority of vehicles decelerate as they approach the intersection,
many vehicles do not engage in the second stage of rapid deceleration needed in order to come to
a complete stop. Instead, the vehicle either holds a constant velocity through the intersection, or
accelerates once the stop sign has been reached. The vehicle in Figure 5.4 appears to switch from
braking to acceleration once at the stop sign.