In which situation is stationary mode radar typically used?

Stationary mode radar is primarily used when the officer is parked and monitoring traffic. This mode allows law enforcement officers to closely observe and measure the speed of vehicles without moving, providing a stable reference point. By being stationary, the radar can effectively track the speed of oncoming or passing vehicles over a defined area. The setting usually enhances accuracy and ensures that the radar can focus on a specific lane or section of road without the complications that can arise from a moving radar unit.

In this context, the other options do not accurately represent the primary function of stationary mode radar. For example, while measuring the speed of vehicles in traffic (the first option) can happen in stationary mode, it doesn't specifically describe the stationary aspect that is the key identifying feature of this mode. The second option about the radar unit being placed on a tripod could refer to stationary radar but does not encompass the broader context of practical usage where officer presence is a factor. Lastly, handheld laser radar (the fourth option) typically refers to a different type of radar technology and usage, which does not fit the definition of stationary mode radar as it usually involves a moving or handheld approach rather than that of a parked vehicle monitoring traffic.