This question refers to the US standard rules established by the MUTCD (Manual of Uniform Traffic Control Devices) for approach to railroad crossing. Unless a highway-railroad grade crossing is marked with an "EXEMPT" sign, the named vehicles are required to stop not closer than 8 feet from the crossing gate, if equipped, and not closer than 15 feet feet from the closest rail. There is no "farther than" in the Federal requirements or recommendations. The "farther than" is likely a CDL or state requirement.
skids occur when the brakes are applied so hard that the front or rear wheels lose traction
These vehicles must stop no close than 15 feet and no more than 50 feet away from the nearest rail.
100
The tyres of the vehicles does take the weight of all the vehicle, so they does take the weight of passengers as well.
Link below of current 7 passenger vehicles
chock the vehicle
The US had huge production capabilities for aircraft, vehicles and explosives.
Most Light Rail vehicles currently used on US systems have a maximum "crush load" of 225-250 passengers PER CAR. Normal "heavy" loads are 175-200 passengers PER CAR. Remember that Light Rail vehicles sometimes operate as two, or three car trains, equating to as many as 600-750 passengers on a 3 car consist. Crush Loads usually only are seen during post event boardings near sporting or musical events.
Depends which caravan you mean....a group of travellers, merchants or pilgrims, journeying together for safety.....a large covered vehicle for carrying passengers...can be a pack of animals or motor vehicles and in the UK can be a house on wheels similar to an American trailer
100
Mm
High Occupancy Vehicles (HOV), meaning in the US, vehicles that have a driver plus one or more passengers.