Highway Accident Brief - Motorcoach Run-off-the-Road
December 17, 2002
Canon City, Colorado
December 21, 1999
Videos were presented at the Board meeting on December 17, 2002 in Washington, D.C.
Disclaimer: Simulations presented below used the bus's DDEC IV engine recorder data, scene surveys, witness statements, pictures, and vehicle operating characteristics. The depictions do not represent actual lighting conditions at the time of the accident, as it was dark. The blowing snow is not depicted, but the surface friction was modified for wet and slippery conditions.
Vehicle Dynamics: Six different views of the vehicle dynamics were rendered to show various perspectives of the crash. After cresting the hill, and beginning the descent, at the first curve, near milepost 272.3, the bus began to sideslip as the driver went around the left curve at 63 mph with the transmission retarder engaged. The pavement was reported to be slippery with ice and snow. The bus was then placed in neutral and accelerated to 70.5 mph near milepost 273. The bus ran off the road in the curve, struck milepost 273 and the subsequent delineator. The bus was steered back onto the road and it then rotated 180-degrees clockwise, before going off the road on the left side backwards. The bus rotated about 90-degrees more clockwise as it rolled at least 1.5 times. In each of the simulations, a time is shown. This time corresponds with the time indicated by the DDEC IV engine recorder data and the actions indicated are from the recorder, except steering which was added based on the simulation data.
Chase View of the Bus
This view is a chase view of the bus as it descends the mountain, loses control, accelerates, runs off the road to the right, rotates and rolls over to final rest.
Close-Up of the Initial Loss-of-Control
This view is a close-up of the initial loss-of-control at the top of the mountain.
Close-up of the Final Loss-of-Control
This view shows the driver's final loss-of-control, the bus's rotation, overturn and slide to final rest.
View of the Bus's Spin from Nearby a Delineator Struck by the Bus
Note the comparison of the picture on the right that shows the bumper off the rear of the bus where it struck the delineator to the simulation picture. This fixed view shows the bus as it spins around the corner and comes backward toward the delineator.
View of the Spinout and Overturn from Near the Final Rest Position of the Bus
This fixed view shows the bus as rotates, rolls over as bounces to final rest.
Bus Driver's Potential View
This view shows the driver's potential view as he negoti
ates the mountain downgrade. When he loses control the simulated steering required is indicated. The other actions indicated are based on the DDEC IV data.
The simulations were produced on an HVE™ UNIX system using SIMON™ , EDSMAC4™, EDVSM™ and EDGEN™ programs. All of the programs are trademarks of the Engineering Dynamics Corporation. The software, ReadDataFile, developed by Collision Engineering Associates was also implemented for the simulations. These movies were produced in MovieMaker™ and Adobe Premiere™. These programs are trademarks of Silicon Graphics, Inc and the Adobe Systems Incorporated, respectively.