Semi-trucks have a tendency to be heavy and haul a lot of weight. The Sierra tends to have horrible winter storms that pack ice and snow on the grounds. These two things create a recipe for disaster; a disaster that is known as stranded trucks. The combination of weather and the trucks weight themselves causes trucks, and those cars behind them to become stranded, potentially for miles. Instead of having no means to get over the steep grades, they have pusher trucks.
What are Pusher Trucks?
Pusher trucks are specifically made to help trucks of this size. It's like a tug boat that helps ships navigate the harbors at slow rates of speed. Created in Newcastle, they are available 24 hours a day to give semis enough oomph to get up and over the Donner Pass. What happens with the trucks, once they stop, hey don't have enough power to get going again and haul their loads over the steep grade, their tires will spin instead of gripping the road (or snow, or ice).
The trucks themselves are maintained at Superior Equipment repair in Newcastle where the pusher trucks are outfitted with a standard diesel engine and a steel pusher bar that is protected by rubber to prevent damaging the big rig. The most important piece of "tech" is also added there, a concrete block that weighs 8 tons mounted above the back axle to give the pusher the traction and stability to actually push these rigs. And push they do, because they can help a truck weighing up to 80,000 pounds! This is what they are built for and their only use is to get those trucks over the mountain.
How Do They Help
They help after a call has gone out to let them know a truck is stuck. When there is a big storm they can essentially push up to 25 semis per hour and get them going. Usually a quart mile is enough to get the trucks on their way, and have been used in some form for the last 30 years. The current program is a partnership between Caltrans and the California Trucking Association. The trucking groups gives them the trucks (a Freightliner and a Kenworth) and covers the expenses. Caltrans houses the trucks and provides drivers.
Every driver has over-the-road experience which is vital to the business and they are willing and able (and excited) about providing the services that they do. Knowing the CB lingo is important as well because they can directly communicate with the truckers in a language that is universally understood by those behind the radio. These are people that are passionate about what they do and can literally tell you a story about every truck they helped that day.
When Winter is Over
The rigs are brought in to Newcaslte where they are completely overhauled and rested before the next season. Then they are ready for when the first snow falls again. And one of the important parts and the most amazing...the service is free. But each driver of a semi is given a card to give their employer for a donation if they choose to provide one, but even without, the pushers will continue to run and help stranded truckers (and those behind them) over the mountain again come winter.