Effects of a Downstream Signalised Junction on the Capacity of a Multiple Berth Bus-stop
GIBSON J, Universidad de Chile, Chile
Congestion at bus-stops is frequently found in arterial roads carrying heavy bus flows (150 or more buses per hour). Arising delays can be considerably greater than those (more conventional) due to junctions. Under such circumstances, to improve transit l
Congestion at bus-stops is frequently found in arterial roads carrying heavy bus flows (150 or more buses per hour). Arising delays can be considerably greater than those (more conventional) due to junctions. Under such circumstances, to improve transit level of service requires the provision of adequate capacity at bus-stops.
A single berth stop-point can hardly handle et~ficieutly more than 60 buses/h during peak periods. In many cities around the world there are road segments where bus flows are several times higher than that figure. How to manage flows of hundreds of buses per hour, corresponding to dozens of different routes, to/from which thousands of passengers per hour will board/alight along a few blocks? The most effective scheme has proved to be the creation of divided bus-stops. Buses are divided into groups (according to route destinations) that are assigned different stop-points, close to each other but apart enough to avoid interference among stopping buses belonging to different groups.
However, experience shows that often a group flow is still higher than 60 buses/h (reportedly, up to 150 bus/h). Hence the need for multiple-berth stop-points. It is well known that the marginal contribution to capacity of an additional berth decreases rapidly for linear configm'ations, typical of on-road facilities. But designs with two or three berths are quite common.
Capacity of a multi-berth bus-stop is a complex subject. It is not just a matter of the number of berths it has: the way in which they are used, in terms of entry and exit disciplines as welt as the behaviour inside the stopping area, are influential also. To deal with different options in these and other respects, simulation is an appropriate tool. Previous work with this approach has been reported (Gibson et al, 1989) describing the functioning of an isolated bus-stop and the estimation of its capacity and delays by means of a computer program (IRENE).
But in practice it is not easy, and even not possible, to locate several multi-berth facilities with sufficient spacing and, at the same time, distant from signalised junctions. This is specially true for road networks whith a grid pattern. Obviously, the vicinity of a downstream signalised junction may reduce the capacity of a bus-stop.
This paper presents some results on the impact of such junction-bus-stop interaction. They have been obtained with an extended version of IRENE that allows for signalised junctions upstream and/or downstream the bus-stop (version 3.8).
Association for European Transport