Conflicting road rules across cities could be a challenge for AVs

For all the concern over the patchwork of regulations governing AVs from state to state, a similar issue has been largely ignored: idiosyncratic road rules that vary not only state to state but also city to city.

Why it matters: Human drivers in an unfamiliar city will use their knowledge of familiar road rules to determine whether a right turn on red is allowed, for example. AV developers face a much bigger challenge: how to program self-driving software to ensure compliance when the rules of the road vary from one place to another.

Background: Currently, 29 states have passed some kind of legislation for self-driving cars, some more extensive than others.

• NHTSA recently encouraged states to pursue a "consistent regulatory and operational environment," warning that discrepancies between state and local laws lead to confusion and compliance challenges.

Reality check: There are already varying road rules for all road users, not only in all 50 states, but in thousands of cities.

• These variations are not insignificant; states differ, for example, on when vehicles must stop for school buses and how cars should make turns across bike lanes.

Where it stands: Right now, self-driving technology is being tested in limited jurisdictions, so companies can feasibly program rules for each municipality individually.

• As AV companies eventually expand to all 50 states and thousands of cities, that task will become much harder. 

The bottom line: States, cities, and AV companies may eventually need to collaborate to standardize road rules, not just AV regulations.

Charity Allen is the head of regulatory counsel at Aurora.