Short station ramps for AGT systems

Automated guideway transit (AGT) systems often have off-line stations, so that cars can travel directly from an origin to a destination, bypassing the intervening stations. Trip time is reduced, and a more flexible overall management policy is possible. The disadvantage of off-line stations is that additional guideway is required for the station and its associated ramps. More guideway is expensive, both to build and because of the extra space required. Conventional practice has assumed that the ramps leading into and out of off-line stations should be long enough 1) to accelerate to line speed before entering the main guideway and 2) to leave the guideway before decelerating into the station. Careful analysis using a headway safety computer program shows that ramps usually do not have to be this long. Acceleration and deceleration can safely take place on the main guideway. Possible reductions in ramp length are presented for a range of systems characteristics, assuming a constant headway control policy. These are compared with simple reference solutions. It is concluded that acceleration ramps can usually be eliminated. Deceleration ramps can often be greatly shortened, particularly if main guideway headway is sufficient for successive cars to enter a station.