The driver, who suffered a broken leg, remains off work on medical leave. The bus, a 2013 model, was valued at approximately $70,000.
A Tulsa Police report on the crash indicates the bus lost traction on a wet highway.
The driver, 41-year-old Nicole Williams, started driving for TPS at the beginning of the school year in 1997. Before the accident, she had an unblemished driving record, according to the Oklahoma Department of Public Safety.
TPS says the GPS data recorded as the accident was happening indicate the bus was moving at 57 miles an hour 25 seconds before it started hydroplaning. The posted speed limit at the accident site is 65 mph, according to Tulsa Police. At the moment TPS believes the bus lost traction, GPS records show it was moving at 51 miles an hour. The bus hit a guardrail at 42 miles an hour, then slowed to less than 4 miles an hour as it tipped over. The entire accident sequence lasted 17 seconds from the moment the bus lost traction to the time it rolled on the side and stopped, according to TPS. The bus driver had left the school 14 minutes before the accident happened.
Williams was not issued a citation for driving too fast for conditions, according to Tulsa Police. TPD Corporal Steve Wood says even though the bus was traveling 14 miles under the 65 mph posted limit, 51 mph was still too fast for the driver to negotiate the curve on wet pavement.
The bus had 10 passengers from Project Accept, an elementary alternative school, and was traveling south on Highway 75 when it crashed. It has just topped the bridge over Southwest Boulevard. Four of the students and the driver were taken from the scene by ambulance. The driver and a student both suffered a broken leg. The other three students had minor injuries.
4/8/2015 Related Story: Five Hurt When Tulsa School Bus Rolls Over On Highway 75
According to police, the tires on the bus all had at least 4/32" of tread left - which is the legal limit for tread depth on truck tires. The tread depth ranged from 5/32" on a rear tire to 12/32" on one of the front tires.
Tulsa Public School released video recorded on board the bus, but only the view from one camera out of four installed on the bus. Because the other cameras views show students, TPS withheld the video citing concerns about student privacy.