Empty miles

Deadheading is the transport term for a vehicle traveling without a passenger. For a driverless ride service, those miles can occur while the car heads to its next rider, repositions for demand, returns for charging, or keeps moving because it has nowhere legal to wait.

A 2026 analysis of a large California sample of Waymo trips found that only about half of the miles carried a passenger. The remaining miles were empty. That changes the traffic calculation: the service may move people efficiently on some trips while still adding substantial vehicle movement between trips.

San Francisco issued thousands of parking tickets to driverless cars in 2025 and 2026 for stopping in bus areas, bike lanes, and other restricted curb spaces, with fines on the order of a million dollars. Those tickets are evidence of an operating conflict, not a minor paperwork issue.

If an empty car has no legal place to wait, it will often keep moving. That can block Nia’s delivery van at the curb and add traffic to the lane. A city evaluating driverless service should measure empty miles and waiting behavior alongside passenger trips.