While the “bus versus light-rail” argument over Dominion Road and Airport “mass transit” is now settled, it is inevitable that this argument will come up over and over again as we develop Auckland’s strategic public transport network over the coming years.
There are a number of different corridors that we might end up having a “bus versus light-rail” argument in the future. Theoretically we need to look at this question for all the “future strategic public transport” corridors. So it’s useful to think about the types of corridors that busways or bus rapid transit (BRT) might be best suited to, and those that are better suited to light-rail. In the Congestion Free Network 2 map we created two light-rail lines (blue and orange in the map below) with the other non-rail corridors being served by a variety of different types of bus infrastructure.
There are lots of arguments over bus versus light-rail internationally. A good starting point is to ignore anyone suggesting that the answer will always be one or the other. Both modes have their strengths and weaknesses, which means that the choice comes down to the characteristics of the corridor you’re looking at. To understand this in more detail it’s useful to look at how some of these mode decisions have been made in recent times, both in Auckland and overseas. The “Committee for Perth” also have a pretty good summary of the strengths and weakness of each mode, and therefore the corridors each may be best suited to.
First, let’s look Auckland Transport’s analysis to reach the conclusion that light-rail is needed along the Dominion Road/Queen Street corridor instead of bus improvements. The key driver for the project is addressing the very large number of buses trying to access the city centre along Symonds Street and Wellesley Street. The same issue exists on Fanshawe St for North Shore services.
The extremely high number of buses simply overwhelm the ability of these corridors to operate effectively. Reading a bit more into the detail of the issue, the large number of buses creates a whole variety of issues:
- Insufficient space at bus stops for buses to wait while people getting on and off the bus
- Too many buses to get through traffic light phases efficiently. This also prevents the ability to do signal preemption to speed up services.
- Too many buses to turn around efficiently at the beginning and end of their services
Work on North Shore rapid transit also highlights the key trigger for needing to upgrade this corridor is when demand simply overwhelms the ability of the busway (particularly in the city centre and around busway stations) to efficiently meet demand:
In choosing light-rail for the Northwest Corridor in the Congestion Free Network, once again a key driver was projections of a large number of buses on city centre streets ill-suited to them. We said this:
Light rail was chosen due to its ability to provide long-term capacity for the Northwest while removing high numbers of future buses from the city centre, freeing up capacity for more isthmus and Onewa services. The route also helps address the possible imbalance between the North Shore and Dominion Rd/South-west/Airport demand, by splitting North Shore services between two routes.
Currently, the main buses from Westgate the 080/081 (Other routes are less direct) take between 1hr, and 1hr 45m to reach the CBD10. At 18.5km with an average speed of 40km/h (Speed will be higher in some sections, slower on others) the light rail will take 28 minutes, cutting between 32m to a 1hr 17m off a trip.
Looking around the world the shift from bus to light-rail seems to have similar drivers. In Sydney the key issue definitely seems to be about increasing capacity to their city centre in a way that is just not possible through more buses, or even through bigger buses. There’s also a strong link to improving city centre amenity, like in Auckland:
This doesn’t mean that every time there is a need for more capacity or improvements along a bus corridor, we need to shift to light-rail. In Auckland we have two good examples – one that exists and one planned – of bus rapid transit projects (albeit that one will need to be upgraded to light-rail in the longer run):
- The Northern Busway shows us an excellent example of the benefits of bus rapid transit – we were able to build this project reasonably cheaply, leverage off existing infrastructure (in this case the Harbour Bridge) and also seamlessly link the trunk corridor with feeder arterial roads – mainly in the form of the various express “L shaped” routes that operate.
- The Eastern Busway (AMETI) is another good example of a route well suited to bus rather than light-rail. It will have lower bus volumes and it’s location is away from the dense, space constrained city centre. Light-rail here would either need to duplicate heavy rail between Panmure and the City, or could result in a silly “two-transfer” scenario where people catch a feeder bus to Botany, light-rail from Botany to Panmure and then heavy rail from there to the city (or wherever else they are heading).
In both corridors it’s also fair to say that the existing land-use patterns present a number of challenges in achieving the kind of ‘transit oriented development’ that light-rail can be a catalyst for. The Northern Busway is next to a motorway and the Eastern Busway runs through the most car dependent part of Auckland, with much of its route along Ti Rakau Drive – a very unfriendly route for pedestrians and high intensity land-use activities.
So, let’s take a look at the different types of corridors where light-rail and bus rapid transit might perform strongly:
- Corridors with particularly high bus volumes and projected future demand
- Corridors serving constrained, high-amenity locations where expanding road space for extra capacity, loading or turnaround facilities is particularly difficult
- Corridors with lots of good opportunities for transit oriented developments and intensification.
Bus Rapid transit
- Lower demand corridors and those serving less constrained locations
- Corridors where there is huge value in being able to implement an improvement incrementally and leverage off existing infrastructure
- Corridors with less opportunity for transit oriented development and intensification.
Using these three tests should be useful in guiding decisions about Auckland’s future strategic PT corridors. For example, it suggests that bus will probably be fine for the Airport to Manukau to Botany route (lower demand and less constrained terminus points) and for the Upper Harbour Westgate to Albany corridor (same points as above, and probably even less opportunity for land-use change).
There are however a couple of complicating factors in all of this:
- Logically, routes would evolve from bus to light-rail over time. As Ottawa has been experiencing this over the last few years, transitioning from one to the other is very challenging. Depending on how far out the timing of this transition might be, it might be better to jump to light-rail earlier than is strictly necessary. The North West corridor is a particularly good example of this and locally the North Shore will probably illustrate how difficult the transition is.
- Technology is developing in this space, which means that the differences between bus rapid transit and light-rail will probably decline over time. However with pressing needs we can’t wait forever for this technology to evolve before jumping in.