Question

Tollbooth stations on roadways and bridges usually have a piece of wire stuck in the pavement before them that will touch a car as it approaches. Why is this done?

Short answer

The wire is attached to the pavement before tollbooth stations in roadways and bridges so that the accumulated charges on the car get discharged before causing harm to the people in the tollbooth.

Step-by-step solution

Static electricity

When two different materials are rubbed together, they produce static electrical charges on their surface and produce static electricity.

Attaching a small wired to the pavement

Due to friction between the car and the air molecules, static charges developed onto the car. Suppose the car moves with greater velocity, more static charges develop onto it.

When the car reaches the tollbooth, there is a chance that these collected charges discharge when coming close to the metal barricades in the booth and can cause harm to the people in the booth.

Hence, a small wire is placed attached to the pavement before tollbooth stations on roadways and bridges so that the accumulated charges on the car get discharged before causing harm to the people in the tollbooth.