Waymo issued a voluntary NHTSA software recall covering 3,800 Gen 5/6 ADS robotaxis after vehicles drove into flooded roads and one was swept into a creek.
Key Takeaways
Trigger incident: April 20, a Waymo AV in San Antonio entered a flooded road with no passengers and was swept into a creek, prompting an NHTSA probe.
Recall covers all U.S. vehicles running Waymo’s fifth and sixth generation automated driving systems.
Mitigation already active: Waymo has restricted operating zones during extreme weather to avoid flash-flood-prone areas pending the full software update.
San Antonio service remains suspended; Waymo says it is “readying operations to resume public rides.”
Pattern of edge-case failures: prior incidents include failing to yield to school buses and causing gridlock during San Francisco power outages in December.
Hacker News Comment Review
Commenters note that distinguishing wet pavement from deep standing water is a genuinely hard sensor-fusion problem; the DARPA Grand Challenge era solution was a dedicated water depth sensor, which Waymo’s LIDAR-plus-camera stack does not appear to use.
There is consensus that “recall” here means a software OTA update plus temporary geographic service suspension, not physical vehicle retrieval – commenters flagged the terminology as misleading but noted Waymo did pull cars from high-risk areas.
Texas geography was cited as an aggravating factor: flat terrain, limestone substrate, and low-water crossings make flash flooding unusually frequent and hard to predict from map data alone.
Notable Comments
@Animats: Suggests equipping AVs with active water-depth sensors, noting this was done on a 2005 DARPA Grand Challenge vehicle; cautions it may cause excessive caution at shallow puddles.
