As a Log truck driver (from Northern California) its simple why this truck didnt make it up the hill....yes lockers to help and should have been engaged(if hill was straight with no turns...if hill did have any kind of a turn in it with lockers fully locked in truck wouldn't be able to steer and would just push straight) so theres 1 reason...2nd..this guy didnt have enough speed built up for the hill...3rd reason and most importantly of all...the truck was loaded too heavy on the ass end and not loaded heavy enough up front on the drivers(drive axles)...I've climbed thousands of hills...steep ass hills...and the trick of the trade is to put as much weight up front as possible by having the "butt" ends of the logs up front and keep the trailer lite....plus as i said...having speed built up for the hill and having all lockers locked