Automated Microbus Recovery from Vehicle Failure


A feature of the Automated Microbus system is that the exclusive roadways are two-way everywhere. The two lanes are separated by a barrier that's high enough to prevent head-on collisions, yet no higher than the vehicle floor. This allows a vehicle in the adjacent lane to easily evacuate passengers in event of failure. Stations and intersections have some one-way roadway, but they are at grade and are designed so that there is generally open space next to vehicle paths, thus allowing another vehicle to pull up for easy evacuation.

No special vehicles are used for evacuation and towing. All Microbuses are assumed to capable of these functions. The vehicles are assumed to be "smart" so that if given a single command, they will position themselves properly for whatever function they have been assigned.

The diagrams below show how passengers can be evacuated from a failed vehicle, which is then towed away.

Microbus stopped on roadway
Microbus fails and stops on two-way exclusive roadway.

Microbuses in other lane passing slowlyMicrobuses in other lane pass at about 3 mph (5 kph). They are ready to stop in case passengers on the failed vehicle disobey instructions and force open the doors and step out. Sensors in the vehicles can detect anyone on the guideway. They have good enough computer vision that they can detect a open door on a failed vehicle, in which case they wouldn't move past it. In most cases, capacity along the other lane won't be significantly affected, because headway can still be 5 seconds (3 mph = 4.4 ft/sec, so vehicles are 4.4*5 = 22 ft nose to nose, and the minimum spacing of the 12.5 ft vehicles would be 22 - 12.5 = 9.5 ft = 2.9 m, which is greater than the stopping distance). This is different than the case of autos on a freeway slowing down to observe an accident. In that case the original headway is very short (about 2 seconds) and vehicles are longer, and it's not possible to maintain lane volume at very low speeds. Another possibility is for each Microbus to have an exterior forward-looking video camera connected to central control. This would allow vehicles in the adjacent lane to pass a failed vehicle one at a time under remote manual longitudinal control. However, this would take longer per vehicle and reduce lane capacity.

Evacuation Microbus pulls upStandard Microbus with one system employee and some hand carried equipment pulls up next to failed vehicle to evacuate passengers. The evacuation vehicle follows a preprogrammed routine to position itself a precise distance from the failed vehicle, even if the failed vehicle is off-center in its lane.

System employee lays down evacuation bridgeThe system employee (shown as a red circle) steps out of the evacuation vehicle, and lays down a hand-carried "bridge" just wide enough to connect the vehicles. This would be an aluminum or composite plate, about 30 inches (76 cm) wide and 60 inches (152 cm) long. The bridge hooks into slots in each vehicle.

Passengers transfer to other vehicleThe system employee opens the doors and roof panel of the failed vehicle, manually if necessary. All passengers, even wheelchair users, transfer to evacuation vehicle.

Evacuation vehicle departsEmployee takes up bridge and evacuation vehicle departs. Central control debriefs passengers via audio link.

Tow vehicle arrivesMeanwhile, a standard Microbus with no passengers has been backing down the lane in front of the failed vehicle. It will do the towing.

System employee connects vehiclesEmployee checks front wheels of failed vehicle to be sure they are able to track tow vehicle correctly. The automatic steering mechanism is disconnected if necessary. In rare cases it would be necessary to place a dolly under the front end. The employee installs towing equipment on each vehicle (this would take perhaps a minute). The tow vehicle then follows a preprogrammed routine to position itself correctly, and the employee connects the tow bar of the rear vehicle with the tow ball of the front one.

Failed vehicle is towed awayEmployee loads equipment into tow vehicle and then boards. Failed vehicle is towed away.