A fatal traffic accident involving two commercial vehicles in Cumberland County has had traffic tied up most of the day on I-40 west bound.  The accident happened around 6am at the westbound 315 mile marker and brought traffic to a standstill for several miles with only one lane open. Eyewitnesses say it involved two tractor-trailers with one catching fire. The driver killed in the accident is from South Carolina.  The other driver, also from South Carolina,  was not injured