What is occupancy in traffic engineering?

Occupancy in traffic engineering specifically refers to the fraction of time that a detector is occupied by a vehicle. This concept is fundamental to understanding how traffic flow is monitored and analyzed.

When a vehicle passes over a detector, which might be a loop sensor embedded in the road surface, the sensor registers that it is occupied during the time the vehicle is present. Occupancy is measured as a percentage of the total observation time; for example, if a detector records an occupancy of 30%, this means the detector was occupied by vehicles for 30% of the time being measured.

This measurement is important for traffic management because it helps to indicate congestion levels, average vehicle flow rates, and overall road performance. A higher occupancy indicates that more vehicles are present over a longer duration, signaling congested conditions, while lower occupancy suggests smoother traffic flow.

This definition of occupancy distinguishes it from other concepts such as vehicle count or total travel distance, which are not related to the duration of presence on the detector, making it a key metric in traffic engineering.