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He aha te mea nui ki tēnei ao? Māku e ki atu. He tangata, he tangata, he tangata.
— Māori Proverb
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 live in the city without needing a car to get around, 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. “Buses aren’t doing it for Wellington any more: there are too many of them, they’re too noisy, take up too much space, and get in everyone’s way (including each other), causing delays. That’s why we need more of them — rapid ones.” This doesn’t make sense, but it’s taking us a long time to work out what the right questions are.
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.
Transit 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.
The trade-off is initial spending for long-term gain or permanently higher expenditure. An economically rational and responsible government should aim to provide the highest quality service at the highest overall benefit–cost ratio. The reason more buses seems like a better option than the one that works in other cities is that we are approaching the problem backwards.
To give a light rail proposal the best chance of success, planners have to put one goal above all others — maximize ridership. For light rail to work for Wellington, planners need to design a service that will be economically viable, then ask engineers how to build it.
Some cities favour light rail to meet social goals (it enables density-done-well) and environmental goals (it has zero emissions). Nevertheless, for cities considering light rail, economics will win in the end, because 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 serve dense residential areas and busy destinations, with good connections to buses and suburban rail services. It needs to go to places that are busy all day, like shopping areas, the regional hospital, and airport. It should avoid places where few people live, like the town belt.
If a route has lots of buses carrying lots of people, it’s a good candidate for light rail. If the buses are standing-room only, this suggests suppressed demand 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. Buses really are better for some trips. Some bus routes may provide local (in future autonomous) services for the “last kilometre” at light rail stops. In the same way, at the railway station light rail offers connections to heavy rail.
Successful public transport needs to be there when people need it. This means light rail needs to run 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. Either the frequency on each arm of the Y is half the frequency on the main branch, so people have to wait twice as long. Or one arm operates as a shuttle, forcing its passengers to change vehicles where the line branches.
To pay for itself, a Y-shaped route needs higher ridership than a straight-through route. 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 far apart and too unreliable. Running a frequent, reliable timetable solves that problem.
Light rail trips need to be fast, predictable and reliable. This means the line must be long enough and fast enough to deliver bankable time savings — at least 5km with widely-spaced stops. Light rail vehicles need to operate on an exclusive right-of-way, with priority over regular traffic at all intersections. At the busiest intersections, grade separation may be necessary, running light rail either on a bridge or in a tunnel. 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. Yes, cars and buses will sometimes have to wait for the light rail at intersections, but evidence from other cities consistently shows that this slows up traffic 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 own 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 is succeeding 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 Wellington is big enough and dense enough for a well-designed light rail proposal to succeed. If a light rail proposal for Wellington has a poor IRR and BCR, we need to find and fix planning assumptions getting in the way of maximizing ridership. Form follows function: solve the economic problem, then the engineering one.
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 (it enables density-done-well) and environmental goals (it has 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 rail services. It needs to go to places that are busy all day, like shopping areas, the regional hospital, and airport. It should 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.
Successful PT needs to be there when people need it. This means light rail needs to run 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.
Buses are better for some trips — don’t make people transfer from bus to light rail to go 1–2 stops. Some bus routes provide local (and in future autonomous) services for the “last kilometre” at light rail stops. In the same way, at the railway station light rail offers connections to heavy rail.
Light rail needs to be there when people need it. This means light rail needs to run 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.
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. Buses really are better for some trips. Some bus routes may provide local (in future autonomous) services for the “last kilometre” at light rail stops. In the same way, at the railway station light rail offers connections to heavy rail.
Successful public transport needs to be there when people need it. This means light rail needs to run 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.
To pay for itself, a Y-shaped route needs higher ridership than a straight-through route.
To pay for itself, a Y-shaped route needs higher ridership than a straight-through route. Instead, keep it simple: start with a single light rail route and use buses to transfer people out from the central route 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 far apart and too unreliable. Running a frequent, reliable timetable solves that problem.
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.
A light rail proposal viewed only through an economic lens will not reflect our city’s liveability or our values. We know light rail is succeeding 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.
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. Yes, cars and buses will sometimes have to wait for the light rail at intersections, but evidence from other cities consistently shows that this slows up traffic 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 own 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 is succeeding 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.
Wellington is an ideally-sized city for light rail. The right system now will help reduce congestion, encourage transit-oriented development, and increase residential densities along key routes. What would the right system look like?
Wellington is an ideally-sized city for light rail. The right system now will help reduce congestion, make it more practical for people to live in the city without needing a car to get around, 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. “Buses aren’t doing it for Wellington any more: there are too many of them, they’re too noisy, take up too much space, and get in everyone’s way (including each other), causing delays. That’s why we need more of them — rapid ones.” This doesn’t make sense, but it’s taking us a long time to understand what the right questions are.
Light rail uses space more efficiently than any form of bus-based transit — high-capacity BRT is impractical in Wellington’s narrow CBD. Travel by private car needs up to 20 times as much space as travel by light rail.
Light rail uses space more efficiently than any form of bus-based transit — high-capacity BRT is impractical in Wellington’s narrow CBD. Travel by private car needs up to 20 times as much space as travel by light rail.
The trade-off is initial spending for long-term gain or constant (higher) expenditure. An economically rational and responsible government should aim to provide the highest quality service at the highest overall benefit–cost ratio. The only reason more buses seems like a better option than the one that works in other cities is that we are approaching the problem backwards.
Buses are better for some trips — don’t make people transfer from bus to light rail to go 1–2 stops. Some bus routes provide “last kilometre” services at light rail stops. In the same way, at the railway station light rail offers connections to heavy rail.
Buses are better for some trips — don’t make people transfer from bus to light rail to go 1–2 stops. Some bus routes provide services for the “last kilometre” at light rail stops. In the same way, at the railway station light rail offers connections to heavy rail.
A branching, Y-shaped route, as proposed in the PTSS, makes a high-frequency service expensive. Either the frequency on each arm of the Y is half the frequency on the main branch, so people have to wait twice as long. Or one arm operates as a shuttle, forcing its passengers to change vehicles where the line branches.
A branching, Y-shaped route, as proposed in the PTSS, makes a high-frequency service expensive. Either the frequency on each arm of the Y is half the frequency on the main branch, so people have to wait twice as long. Or one arm operates as a shuttle, forcing its passengers to change vehicles where the line branches.
Abundant evidence from comparable overseas cities tells us that Wellington is big enough and dense enough for a well-designed light rail proposal to succeed. If a light rail proposal for Wellington has a poor IRR and BCR, we need to find and fix planning assumptions getting in the way of maximizing ridership.
Abundant evidence from comparable overseas cities tells us that Wellington is big enough and dense enough for a well-designed light rail proposal to succeed. If a light rail proposal for Wellington has a poor IRR and BCR, we need to find and fix planning assumptions getting in the way of maximizing ridership. Form follows function: solve the economic problem, then the engineering one.
If a route has lots of buses carrying lots of people, it’s a good candidate for light rail. If the buses are standing-room only, this suggests suppressed demand and planners need to prepare for rapid initial growth. Buses are better for some trips — don’t make people transfer from bus to light rail to go 1–2 stops.
If a route has lots of buses carrying lots of people, it’s a good candidate for light rail. If the buses are standing-room only, this suggests suppressed demand and planners need to prepare for rapid initial growth.
Buses are better for some trips — don’t make people transfer from bus to light rail to go 1–2 stops. At the railway station, light rail acts as a feeder service for heavy rail, in the same way that some bus routes provide “last kilometre” services for light rail.
Light rail uses space more efficiently than all forms of bus-based transit — high-capacity BRT isn’t even possible in Wellington’s narrow CBD. Travel by private car needs up to 20 times as much space as travel by light rail.
Transit 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 carries 7 times as many people.
Light rail uses space more efficiently than any form of bus-based transit — high-capacity BRT is impractical in Wellington’s narrow CBD. Travel by private car needs up to 20 times as much space as travel by light rail.
Transit 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 moves 7 times as many people.
Some cities favour light rail to meet social goals (it enables density-done-well) and environmental goals (it has zero emissions). Nevertheless, for cities considering light rail, economics will win in the end, because the people holding the money need to know that light rail is the best value option.
Some cities favour light rail to meet social goals (it enables density-done-well) and environmental goals (it has zero emissions). Nevertheless, for cities considering light rail, economics will win in the end, because the people holding the money need to know that light rail is the best value way to move the most people.
If a route already has a lot of busy buses, it’s a good candidate for light rail. If buses are standing-room only, there is likely to be suppressed demand. Planners need to prepare for rapid initial growth.
If a route has lots buses carrying lots of people, it’s a good candidate for light rail. If buses are standing-room only, there is likely to be suppressed demand. Planners need to prepare for rapid initial growth. Buses are better for some trips — don’t make people transfer from bus to light rail to go 1–2 stops.
A branching, Y-shaped route, as proposed in the PTSS, makes it expensive to operate a high frequency service. Either the frequency on each arm of the Y is half the frequency on the main branch, so people have to wait twice as long. Or one arm operates as a shuttle, forcing its passengers to change vehicles where the line branches.
To pay for itself, a Y-shaped route needs higher ridership than a route which doesn’t branch.
A branching, Y-shaped route, as proposed in the PTSS, makes a high-frequency service expensive. Either the frequency on each arm of the Y is half the frequency on the main branch, so people have to wait twice as long. Or one arm operates as a shuttle, forcing its passengers to change vehicles where the line branches.
To pay for itself, a Y-shaped route needs higher ridership than a straight-through route.
A light rail proposal viewed only through an economic lens will not reflect our city’s liveability or our values. We know light rail is succeeding when its riders mirror the diversity of the city and region it serves. Rich and poor, young and old, people of all shapes, sizes and abilities find it inviting and welcoming.
Abundant evidence from comparable overseas cities tells us that Wellington is big enough and dense enough for a well-designed light rail proposal to succeed. If a light rail proposal for Wellington has a low IRR and low BCR, we need to find and remove barriers in the way of maximizing ridership. Will LGWM do this?
A light rail proposal viewed only through an economic lens will not reflect our city’s liveability or our values. We know light rail is succeeding 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 Wellington is big enough and dense enough for a well-designed light rail proposal to succeed. If a light rail proposal for Wellington has a low IRR and BCR, we need to find and fix planning assumptions getting in the way of maximizing ridership. Will LGWM do this?
Transit economics are simple: buses are cheap to buy, expensive to operate; light rail is expensive to buy, cheap to operate. Three factors drive this. A light rail vehicle —
Therefore, if you want a light rail service to be economic, one goal sits above all others:
Maximize Ridership
Wellington is an ideally-sized city for light rail. The right system now will help reduce congestion, encourage transit-oriented development, and increase residential densities along key routes. What would the right system look like?
Light rail uses space more efficiently than all forms of bus-based transit — high-capacity BRT isn’t even possible in Wellington’s narrow CBD. Travel by private car needs up to 20 times as much space as travel by light rail.
Transit 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 carries 7 times as many people.
To make light rail economics work for Wellington, one goal must sit above all others — maximize ridership.
A city may favour light rail to meet social goals (it enables density-done-well) and environmental goals (it has zero emissions). Nevertheless, economics will win in the end, because the people holding the money need to know that light rail is the best value option. To give a light rail proposal the best chance of getting approved, planners need to do everything they can to maximize its ridership.
Start by designing a service that will be economically viable, then ask the engineers how to build it.
First, light rail needs to go where lots of people are. This means light rail needs to serve dense residential areas and busy destinations, with good connections to buses and suburban rail services. It needs to go to places that are busy all day, like shopping areas, the regional hospital, and the airport.
If a route already has a lot of busy buses, it’s a good candidate for light rail. If buses are standing-room only, there is likely to be suppressed demand. Plan for rapid initial growth.
Second, light rail needs to be there when people need it. This means light rail needs to run 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 makes it expensive to operate a high frequency service. The service on the arms of the Y must be one of the following:
Some cities favour light rail to meet social goals (it enables density-done-well) and environmental goals (it has zero emissions). Nevertheless, for cities considering light rail, economics will win in the end, because the people holding the money need to know that light rail is the best value option. To give a light rail proposal the best chance of getting approved, planners need to do everything they can to maximize its ridership.
Planners need first to design a service that will be economically viable, then ask the engineers how to build it.
Light rail needs to go where lots of people are. This means light rail needs to serve dense residential areas and busy destinations, with good connections to buses and suburban rail services. It needs to go to places that are busy all day, like shopping areas, the regional hospital, and the airport. It should avoid places where few people live, like the Wellington town belt.
If a route already has a lot of busy buses, it’s a good candidate for light rail. If buses are standing-room only, there is likely to be suppressed demand. Planners need to prepare for rapid initial growth.
Light rail needs to be there when people need it. This means light rail needs to run 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 it expensive to operate a high frequency service. Either the frequency on each arm of the Y is half the frequency on the main branch, so people have to wait twice as long. Or one arm operates as a shuttle, forcing its passengers to change vehicles where the line branches.
Third, light rail trips need to be fast, predictable and reliable. This means the line must be long and fast enough to deliver bankable time savings — at least 5km with widely-spaced stops. Light rail vehicles need to operate on an exclusive right-of-way, with priority over regular traffic at all intersections. At the busiest intersections, grade separation may be necessary, running light rail either on a bridge or in a tunnel.
Light rail trips need to be fast, predictable and reliable. This means the line must be long and fast enough to deliver bankable time savings — at least 5km with widely-spaced stops. Light rail vehicles need to operate on an exclusive right-of-way, with priority over regular traffic at all intersections. At the busiest intersections, grade separation may be necessary, running light rail either on a bridge or in a tunnel. It’s about 9km from the rail station to Miramar, a travel time about 20 minutes.
How do you tell whether light rail is succeeding? Its ridership mirrors the diversity of the city it serves. It’s equally inviting to rich and poor, young and old, people of all shapes, sizes and abilities.
The moral of the story is that if a light rail proposal has a negative NPV or low benefit–cost ratio, look for and remove barriers getting in the way of maximizing ridership. Wellington is big enough and dense enough for a well-designed light rail proposal to succeed.
A light rail proposal viewed only through an economic lens will not reflect our city’s liveability or our values. We know light rail is succeeding when its riders mirror the diversity of the city and region it serves. Rich and poor, young and old, people of all shapes, sizes and abilities find it inviting and welcoming.
Abundant evidence from comparable overseas cities tells us that Wellington is big enough and dense enough for a well-designed light rail proposal to succeed. The moral of the story is that if a light rail proposal for Wellington has a low IRR and low BCR, find and remove barriers getting in the way of maximizing ridership. Will LGWM do this?
(:typeset-page fontset=kepler parasep=space subtitle="Economics before Engineering" headingcolor=RoyalBlue colophon=off :)
Third, light rail trips need to be fast, predictable and reliable. This means the line needs to be long enough to deliver bankable time savings — at least 5km. Light rail vehicles need to operate on an exclusive right-of-way, with priority over regular traffic at all intersections. At the busiest intersections, grade separation may be necessary, with light rail running either on a bridge or in a tunnel.
Third, light rail trips need to be fast, predictable and reliable. This means the line needs to be long and fast enough to deliver bankable time savings — at least 5km with widely-spaced stops. Light rail vehicles need to operate on an exclusive right-of-way, with priority over regular traffic at all intersections. At the busiest intersections, grade separation may be necessary, with light rail running either on a bridge or in a tunnel.
Start by designing a service that will be economically viable, then ask the engineers how to build it.
He aha te mea nui ki tēnei ao? Māku e ki atu. He tangata, he tangata, he tangata.
— Māori Proverb
Transit economics are simple: buses are cheap to buy, expensive to operate; light rail is expensive to buy, cheap to operate. Three factors drive this. A light rail vehicle —
Therefore, if you want a light rail service to be economic, one goal sits above all others:
Maximize Ridership
A city may favour light rail to meet social goals (it enables density-done-well) and environmental goals (it has zero emissions). Nevertheless, economics will win in the end, because the people holding the money need to know that light rail is the best value option. To give a light rail proposal the best chance of getting approved, planners need to do everything they can to maximize its ridership.
First, light rail needs to go where lots of people are. This means light rail needs to serve dense residential areas and busy destinations, with good connections to buses and suburban rail services. It needs to go to places that are busy all day, like shopping areas, the regional hospital, and the airport.
If a route already has a lot of busy buses, it’s a good candidate for light rail. If buses are standing-room only, there is likely to be suppressed demand. Plan for rapid initial growth.
Second, light rail needs to be there when people need it. This means light rail needs to run 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 Y-shaped route makes it expensive to operate a high frequency service. The service on the arms of the Y must do one of the following:
To pay for itself, a Y-shaped route needs higher ridership than a route which doesn’t branch.
Third, light rail trips need to be fast, predictable and reliable. This means the line needs to be long enough to deliver bankable time savings — at least 5km. Light rail vehicles need to operate on an exclusive right-of-way, with priority over regular traffic at all intersections. At the busiest intersections, grade separation may be necessary, with light rail running either on a bridge or in a tunnel.
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 will attract fewer riders.
How do you tell whether light rail is succeeding? Its ridership mirrors the diversity of the city it serves. It’s equally inviting to rich and poor, old and young, people of all shapes, sizes and abilities.
The moral of the story is that if a light rail proposal has a negative NPV or low benefit–cost ratio, look for and remove barriers getting in the way of maximizing ridership. Wellington is big enough and dense enough for a well-designed light rail proposal to succeed.