As I write this article we are preparing for a mission trip back to Guatemala to train their firefighters and rescue folks. This will be our fourth trip back down, and we have a great group of Instructors that will be going. We are spending two days with the firefighters covering vehicle extrication and stabilization. One of the big issues they have there is bus wrecks.
School bus with old style windows — notice metal divider.
They use buses as a major player in their transportation system. These buses are hand me downs a lot of the time, so they are not always as safe as they could be. The buses usually carry twice the number we carry here in the states, and most are school buses that are converted. With all of the mountains they have to travel, bus wrecks can be frequent and deadly. This will give me lots of training material when I return.
We covered a lot of information over the past several years on heavy vehicle rescue. Before we completely leave the topic of heavy vehicle rescue, I would like to look at bus extrication for a few issues to come. Buses still technically fall under the pretenses of heavy vehicle, and I think this would be a good time to cover the subject matter.
There are four classifications of buses we can look at, A through D. I want to concentrate right now on the ones we deal with and see the most, types C and D. These are also the larger buses that would give us more problems during an extrication. We are going to look at school buses for now, and then may discuss commercial buses in a future article.
School bus with new style windows.
Type “C” buses are sometimes referred to as conventional buses. These buses are custom built on an extended chassis and a custom cab. They have a GVW (gross vehicle weight) of over 21,500 pounds and can carry 10 plus students. They are built on an assembly line where the chassis, frame and cab are assembled. The frame work is then constructed for the passenger compartment to include sides and top. The wall and roof framing are sometimes all one piece of 12 to 14 gauge galvanized steel. They run between the windows to support the walls and roof. The roof usually has roof bows made of 16 gauge galvanized metal that runs from front to rear. The floor beams are eight to 10 gauge beams and 14-gauge sheet metal with plywood. The rear is an “A” frame construction that also houses the rear emergency exit.
The exterior walls are 20 gauge sheet metal and the interior walls are 22 gauge sheet metal. Insulation is also added to the floor, walls and roof. In older built buses the sheet metal was riveted to the top and sides. In some of the newer designed buses, the metal may be glued and riveted. There may be as many as two emergency escape hatches in the ceiling.
Bus with side emergency exit windows.
Looking at the school bus rendering, you can see that the framing is pretty stout and makes the bus a very strong vehicle to work on. This is a big plus when it comes to protecting the valuable cargo inside.
The seat framework is then added to the interior and bolted to the floor and walls. This also gives the bus a more solid construction as things all tie in with each other. The seat cushions are added, as is the heating system and rubber flooring. On the outside they install up to four rub rails for side impact reinforcement. A lot of older buses had only three rub rails, while the newer buses may have four.
The newer designs have also made improvements to the sides, in that they are a bit higher from the ground to give better side impact protection. The rear of the buses from the wheel to the back bumper are angled up. This would allow for a vehicle striking the bus in the rear, to do an underride, instead of hitting the bus square on. This impact would raise the bus rather than direct impact, transferring the force and energy to the kids inside.
Another safety feature and change you will see on new buses is the front window. They are now larger than the traditional windows, wrap around for better driver view, and they are glued in rather than set in a gasket. The window does not have the metal divider in the center either. The side windows are tinted safety glass and some do not open up and down. There are usually several on both sides that have emergency push out for access.
We will continue to look at buses and ways we can extricate our victims in the next issue. School is back in and there will be thousands of buses on the road everyday carrying the future of our world. Be safe out there and train hard to be the best you can.