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Hutia te rito o te harakeke, Kei whea to kōmako e kō? Ki mai ki ahau, He aha te mea nui o te Ao? Maku e kī atu, He tāngata, he tāngata, he tāngata. — Meri Ngaroto
Wellington is an ideally-sized city for light rail. The right system now will help reduce congestion, make it more practical for people to get around without needing a car, and open up more possibilities for higher-density housing such as student accommodation and inner-city family apartments. What would the right system look like?
The answer you get depends on the quality of the question you ask, but it’s taking us a long time to understand what the right questions are. The reason buses seem like a better option than what works in other cities is that we are approaching the problem backwards.
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Light rail uses space more efficiently than any form of bus-based transit — high-capacity BRT is impractical in Wellington’s narrow CBD. A person travelling by private car needs up to 20 times as much space as one using light rail.
PT economics are simple: buses are cheap to buy but expensive to operate; light rail is more expensive to buy but cheaper to operate. Several factors drive this. A light rail vehicle lasts twice as long as a bus, it runs at twice the average speed, and one driver can move 7 times as many people.
Planners need to design a service that will be economically viable, then ask engineers how to build it.
An economically rational government should aim to provide the highest quality service at the highest overall benefit–cost ratio. The trade-off is initial spending for long-term gain or permanently higher expenditure.
To give light rail the best chance of success, planners have to put one goal above all others — maximize ridership. Light rail can help cities to meet social goals (enabling density-done-well) and environmental goals (zero emissions), but economics will win in the end. The people holding the money need to know that light rail is the best value way to move the most people.
Light rail needs to go where lots of people are. This means light rail needs to link dense residential areas and busy destinations, with good connections to buses and suburban trains. It needs to go to places that are busy all day, like shopping areas, the regional hospital, and airport. Avoid places where few people live, like the town belt.
If a route has lots of buses carrying lots of people, especially if the buses are standing-room only, this suggests suppressed demand. It’s a good candidate for light rail and planners need to prepare for rapid initial growth.
Keep buses for what buses do best. Buses are better for some trips — don’t make people transfer from bus to light rail to go 1–2 stops. Bus routes can provide local services for the “last kilometre” at light rail stops. At the railway station light rail offers connections to heavy rail, as part of a regional transport network.
Successful PT needs to be there when people need it. For light rail this means running at a high frequency all day, every day — at least every 6 minutes during peak periods, every 12 minutes off-peak. This frequency can carry at least 5000 passengers/hour in peak periods, 2500 passengers/hour off-peak.
A branching, Y-shaped route, as proposed in the PTSS, makes a high-frequency service expensive, so needs higher ridership than a straight-through route. Typically, each arm of the Y has half as many services as the main branch, so people have to wait twice as long. Or one arm may operate as a shuttle, forcing its passengers to change vehicles where the line branches.
Instead, keep it simple: start with a single central light rail route and use buses to connect people to the rest of the city. People don’t mind transferring when they can be sure their service will be there on time, and soon enough to be useful. Wellingtonians don’t like transfers because our bus services are too infrequent and too unreliable. Running a frequent, reliable timetable solves the problem.
Light rail must be fast and predictable. This means the light rail line must be long enough and fast enough to deliver bankable time savings — at least 5km with widely-spaced stops. Wellington railway station to Miramar is about 9km, travel time 20 minutes.
If you force light rail to compete with other traffic, it will be slower, less predictable and less reliable. It may cost less to build, but it will cost more to operate and attract fewer riders.
Light rail needs an exclusive right-of-way, with priority over regular traffic at all intersections. At the busiest intersections, running light rail either on a bridge or in a tunnel may be necessary. Yes, cars and buses will sometimes have to wait, but evidence from other cities consistently shows that delays are less than waiting at the lights for the hundreds of extra cars and buses that light rail replaces.
New Zealanders know that we have to tailor solutions to suit our values and culture. A light rail proposal viewed only through an economic lens will not reflect our city’s liveability or our values. Light rail succeeds when its riders mirror the diversity of the city and region it serves. People rich and poor, young and old, of all shapes, sizes and abilities find it inviting and welcoming.
Abundant evidence from comparable overseas cities tells us that well-designed light rail can succeed. If a light rail proposal for Wellington has a poor IRR and BCR, we need to find and fix the planning assumptions getting in the way. Form follows function: solve the economic problem, then the engineering one.
Build the right project; build the project right.