The concept of Automated Highway Systems (AHS) came into existence in U.S. around 1990 because of growing highway traffic congestion. Average travel speeds bear large U.S. cities are about 36 miles per hour at rush hour, leading annually to some five billion collective hours of delay and estimated productivity losses of $50 billion nationwide.
An old joke goes as follows the other day I was in the car repair shop when a banged up motorhome was towed in. Apparently, the driver got tired, set the cruise control and went into the back to make sandwich. “Well all recognize the silliness of this act, but what if such an act were possible? In intelligent transportation systems and in particular, automated highways systems are realized, setting your cruise control and going to sleep could become a reality. It is the need of the time. By automating the highways we can have increased highway throughput with the same highway infrastructure, greater level of passenger safety and more passenger comfort.
NEED OF AHS
The cars, trucks and buses caught in chronic traffic jams waste vast amounts of fuel as they emit copious quantity of exhaust. The traditional solution of constructing more and larger roadways is not viable due to high financial, social and environmental costs of such giant projects and the lack of land. More efficient use of the existing road network using advanced technology seems to be the answer. Hence the concept of automated highway systems was put as a solution to the problem.
WHAT IS AHS?
An automated highway system (AHS) is an Intelligent Transportation System (ITS) technology designed to provide for driver-less cars on specific rights-of-way. An automated highway features a lane or a set of lanes on which vehicles equipped with specilised sensors and wireless communication systems could travel under control at closely spaced intervals, perhaps in small convoy or ‘platoons’.
While on the AHS facility, the vehicle will be operated under automated control. With both vehicle and road fitted with control and communication devices, the vehicles are able to communicate with the roadsides. The system enables the car to find out the roadway conditions and receive navigation from the road. Once outside the AHS facility, the vehicle will be moving in its manual mode.
A driver electing to use such an automated highway might first pass through a validation lane. The system would then determine if the car will tolls from the driver’s credit account. Improperly operating vehicles would be diverted to manual lanes. The driver would then steer into a merging area and the car would be guided through a gate onto an automated lane. The following fig. shows an electronic toll collection booth system. This system, developed by Hitachi, allows drivers to pay tolls without stopping at the toll gates.
There are various antennas mounted on the booth which would coordinate with the on-board unit in the car and then would actuate the sensor. By reading the number-plate of the car, the sensor would actuate the computer in the toll booth which would automatically decide the amount of toll fee from the credit account of the owners of the car having the registration number. Thus the car would be safely driven past the toll gate without stopping. How the toll system would work is shown in the next fig.
After passing through the gate, an automatic control system would coordinate the movement of newly entering and existing traffic. Once traveling in automated mode, the driver could relax until the turnoff. The reverse process would take the vehicle off the highway. At this point, the system would need to check whether the driver could retake control, then take appropriate action if the driver were asleep, sick or even dead.