Further Development of the Light Rail Transit System
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An important feature of the overall strategy is the
safeguarding through planning controls of the original
MPR Island Line alignment. This is needed to ensure that
the LRT system can be converted to fully grade-separated
rail rapid transit operation at same stage in the future
should demand levels exceed the capacity of the system in its mixed on-street/tunnel mode of operation.
The maximum capacity of a largely segregated on-street
light rail system is estimated to be 60 two-car trains of 8-
axle LRV's per hour. With a 2.3m wide vehicle and a
low seating ratio, the planning capacity of the system (after allowing for the peaking of demand within the peak hour) is about 22,600 passengers per hour per direction.
The operation of LRV's through a section of tunnel may in
fact result in some loss of capacity owing to the limitations of signalling systems. (On the basis of precedent elsewhere,
it is expected that signalling would be required in tunnel.
It may however legitimately be asked why it is not then necessary for bus operations through tunnels.) Recent
experience in Essen has suggested that 54 trains per hour
may be the limit for an LRT tunnel, though the Essen
subway includes extensive branching of routes. On that basis, the planning capacity of the line in its street/tunnel configuration would be some 20,400 passengers per hour
per direction. This capacity is expected to be reached in
about the year 2000.
Certain measures might then be adopted to defer the need for
extending the tunnel. These include further reductions in
seating provision or the operation of longer trains of LRV's
over the critical central sections, possibly with the coupling
and uncoupling of trains near the tunnel portals.
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