Osaka Expo Autonomous Bus Crash from AI System Communication Error
An autonomous shuttle bus at the 2025 Osaka Expo park-and-ride facility collided with a concrete wall on April 28 after the autonomous system failed to properly engage its parking brake. The cause was a misconfigured data transmission speed that prevented the vehicle from receiving braking commands. Osaka Metro suspended operation of the affected bus fleet and implemented corrected settings before resuming testing.
What happened
On April 28, 2025, an autonomous shuttle bus operating in the Osaka Expo park-and-ride lot experienced a malfunction while traveling from Yumeshima to Maishima. An error appeared on the dashboard, prompting the driver to switch to manual mode.
The cause was misconfiguration of the data transmission speed from the autonomous system to the vehicle. The system was set to transmit initialization data at 500 kbps, a speed the bus could not receive. Repeated unexpected data transmissions caused system faults, preventing the parking brake from engaging properly.
The bus moved forward after the driver left the driver's seat and collided with a concrete wall approximately 50 centimeters high. The vehicle was in ferry operation with no passengers aboard and the driver was unharmed.
Reported impact
The bus sustained partial damage from the collision. Osaka Metro suspended operation of five identical buses pending investigation.
Index analysis
Osaka Metro stated that the autonomous driving system manufacturer bore responsibility for the error. An Osaka Metro official acknowledged that pre-deployment testing of system data transmission should have been performed, noting that no clear rules governed such pre-transmission inspection.
Governance controls
Osaka Metro corrected the system settings and began one week of test operations from June 12 after obtaining approval from the Ministry of Land, Infrastructure, Transport and Tourism and Osaka Prefectural Police.
Classification
Sources and evidence
This record was researched and written by the Index, based on the following original reporting.