A collision that closed the 15th Street bridge near Laramie was caused when a commercial truck left the highway and crashed into the bridge on Sunday, May 21st, at about 1:05 a.m., according to a Wyoming Highway Patrol news release.

Brian M. Nelson, 44, of Sacramento, California, has been charged with operating a commercial motor vehicle over the maximum drive time of 11 hours, for careless driving, driving while under the influence of a controlled substance and misdemeanor possession of suspected methamphetamine, with other charges pending.

According to the release, Nelson was driving a red Volvo semi-truck pulling a loaded flatbed trailer traveling westbound on I-80. Nelson fell asleep at the wheel near milepost 314, investigators believe. The truck veered off to the right side of I-80, struck a guardrail and then collided with the main concrete support pillars under the bridge head-on. There was no evidence of braking or skid marks and the truck was estimated to be traveling at 65 to 70 mph when it crashed. Nelson was wearing his seat belt and walked away from the crash with only minor injuries.

The collision caused one of the exterior bridge columns to collapse and Wyoming Department of Transportation engineers determined it had to be closed to traffic from the top side. The bridge remains open to traffic driving under in on I-80.

WYDOT District 1 Maintenance Engineer Ralph Tarango said WYDOT is still evaluating the stability of the bridge to determine whether it is safe to open to traffic. Tarango said when the bridge is opened, the southbound lane will be used in a single-lane configuration for the time being until repairs begin. Tarango estimates that WYDOT will need three weeks to complete their evaluation and get the southbound lane prepared for use. Tarango said it will be several months before repairs take place.