The collision of two buses, including a popular tourist Duck Bus, on a bridge in Washington State that killed five people and injured 62 others in September was likely caused by a defective left front axle assembly, according to a preliminary report issued by the National Transportation Safety Board (NTSB).
According to the report, the vehicle at fault was an amphibious military vehicle built in 1945 and modified to serve as a tour bus capable of operating on land and in water. The so-called “Duck Bus” had undergone an earlier modification to the left front axle but may not have been included in a 2013 service bulletin from Ride the Ducks International.
The driver of the Ride The Ducks Seattle LLC bus reported hearing a loud bang as the vehicle experienced a mechanical failure in the suspect axle assembly, causing him to lose control. The Duck Bus crossed the center line of State Route 99 on the Aurora Bridge and struck the left side of a motorcoach carrying students from North Seattle College. A Dodge Ram pickup truck and a Toyota Tundra pickup truck were also involved in the crash.
All of the resulting fatalities were passengers aboard the North Seattle College tour bus.
An axle housing modification described in an October 2013 notice issued by Ride The Ducks International, which refurbishes and modifies the amphibious vehicles, is being reviewed as part of the investigation. The stated purpose of the notice was to alert Duck bus owners and provide guidance on a modification to strengthen the axle housing to prevent fractures.
According to the NTSB, the bus owned by Ride The Ducks Seattle LLC had axle modifications, but those alterations were not associated with the service bulletin from Ride The Ducks International.
Meanwhile, lawyers for Ride The Ducks Seattle told the Washington State Utilities and Transportation Commission that the company is anxious to get 10 Duck buses back on the road, saying that they have been inspected. The agency suspended the company’s license to operate after the Sept. 24 crash.
The NTSB’s final report is expected to take several months to complete.