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No. of Recommendations: 5
The only difference would be that the first truck wound have Micra speared all over the front of it. Same as if it had been traveling alone.

Depends on the velocity delta between the Micra and the first truck. Say the Micra has slowed to the offramp speed of 35, when the lead semi, traveling at 80, bunts it. Assume the lead driver, thus all the following semis, apply maximum braking force. Thing is, the lead truck is not only dissipating energy through the brakes, it is also losing energy by accelerating the remains of the Micra to the speed the truck is traveling at. As the lead truck has this secondary loss of momentum, it stops shorter than it would with brakes alone, so the second truck plows into the back of the first.

Under less than maximum braking effort, it would be simple enough to program all the trucks to match the deceleration rate of the lead truck. If the lead truck is applying maximum brake effort however, you could have an alarming pileup simply due to variations in the maximum brake effort of each truck, which will vary with brake lining and tire quality and condition. Even if the coefficient of friction of both brake linings and tires are equal for all the trucks, differences in load will mean variation in the amount of momentum that the uniform amount of braking effort has to overcome, hence each truck has a different stopping distance.

Third thing comes to mind: with only the lead truck occupied, there is no-one to have a "seat of the pants" feel for the other trucks. The train can be humming along in rain, with the lead truck, on new tires, feeling perfectly fine to the driver, while #2, with half worn tires, starts to hydroplane, skids out of control and piles up the rest of the train.

Steve

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