Each weekend we dig into the archives. This post by Nick was first published in June 2012.

Over the past few weeks the blog has featured a range of posts around the City Rail Link, options for staging stations and whether to include an eastern link from the tunnel to Grafton or not. We’ve also had some discussion from Peter about the merits of converting some of rail system to driverless metro operation, and I’m certainly on the record as advocating a metro style solution for a North Shore rail line.

These are all contentious issues which have drummed up much impassioned discussion, and taking a step back reveals why. At the surface these sorts of discussions are about infrastructure and technology: do we build a tunnel here, a linkage there? Do we want drivers in our trains or computer controlled system?  Would a different type of track geometry save us construction costs? What sort of frequency do we want on evenings and weekends, what could we afford to run?

But if we dig down a little further this isn’t really about infrastructure, it’s about what that infrastructure allows us to do. Reading the blog over the last wee while I can’t help but think we’re all actually arguing about something very mundane yet incredibly important: service patterns. I think it all comes down to one fundamental question. Do we want to run our network under a suburban commuter rail model, or as a rapid transit system that works more like a metro?

I’d like to use this post to outline the differences between the commuter and rapid transit service models as I see them, outline my conclusions, then open the floor for discussion. So without further ado let’s review the alternatives.

 The status quo: Commuter rail

Commuter rail, or suburban rail as it is sometimes known, is the service model we have at the moment. The key feature of this model is a focus on weekday peak time commuter travel to central city locations. This focus comes from framing the purpose of rail transit in two basic terms: getting people to work, and relieving traffic congestion. It’s easy to see why this pattern emerges, the city centre on weekdays is the greatest concentration of employment in any city, plus the greatest cause of traffic congestion. So in economic terms there is a certain logic to this model, putting the rail service in where it can be used by the most workers and have the greatest decongesting benefits.

That’s the goal of the model, so what are the resulting features of commuter rail that influence the way it is used?

  • Lower frequencies, typically not much better than ten or fifteen minute headways even at peak times. Travel on the system is assumed to be “appointment” travel where commuters catch the same timetabled services every day. No need to focus on high frequency because passengers follow very regular travel patterns without spontaneous travel at different times of day.
  • Capacity tends to be increased by lengthening trains rather than running them more often. One reason for this is passenger based. If you are focussed on getting weekday commuters to their desks at 9am then you’ll have a lot of people all wanting to arrive downtown at 8.50 am, so it makes sense to make that train longer rather than add another one that gets people to work too late. The other reason in operational, by linking two trains together under the one driver minimise your operating costs. If you run two short trains one after the other, you’ll need to employ two drivers instead of one and the staffing costs are double.

    The greater Boston commuter rail network. Radial, CBD focus with branches, duplication and mixed service patterns
  • A focus  minimising travel time once you are on board, and keeping those travel times consistent. This often comes from peak services patterns that run express or skip stops to shave minutes off travel times. A single line may have a variety of patterns to serve different markets. For example the same set of tracks  might see some all stops trains, some expresses from the outer suburbs that skip all the inner stations, short runners that make up capacity at the inner stations, expresses that only stop at major stations but skip all the small ones, skip stop trains that alternate stopping, the list is endless.
  • Lots of service from the suburbs to the central city. Service are arranged in radial lines that terminate in the CBD, perhaps after passing through a city tunnel or after looping around a series of city stations to distribute commuters. This is very good if you want a regular and comfortable one-seat ride to your office downtown.
  • Short span of service.  Again the focus is on weekday commuters to the city, so there often very little service during the middle of the day, in the evenings or on weekends. Some systems may not run late at night or on Sundays at all when there are no commuters.
  • Transfers are avoided wherever possible, instead lines branch for coverage. This is where trains branch off the main line, dividing frequency of service to cover more area.
  • Trains are often designed around maximising seating for long distance travellers, and relatively low turnover of passengers. This typically means little standing room and fewer doors per carriage to get more seats in, which may come at the expense of congestion around doors at stops.
  • Travelling for the first time usually requires consulting a timetable and a network map, both of which may be quite complicated and hard to understand at a glance.

 The contender: Rapid transit

Rapid transit can mean several things but I’m using it here as a synonym for a metro style service pattern. I don’t want to use the word metro itself because many people associate that with underground rail systems like those of Paris, London or New York, and it’s not the tunnels or infrastructure that are the important thing. Regardless of whether the tracks are underground, elevated or at ground level, it’s the service pattern the trains run that make rapid transit rapid transit. The focus here is on all day travel across the whole network, any day of the week or any time of day. Under the rapid transit model all parts of the network are usually just as accessible as central city stations, and it’s not assumed that people take the same timetabled service every day. Instead rapid transit is designed so that people can travel sponteneously at any day or time, from any origin to any destination. Rapid transit dispenses with the assumption of servicing weekday city commuters and instead tries to service any kind of travel.

So what does this rapid transit / metro look like?

  • High frequency all the times on every line to give -turn-up-and-go freedom to travel whenever and wherever people like. Usually this means at least one train every fifteen minutes at any time of day or night, and up to five minute headways or better at peak.
  • Long span of service, with normal service from early morning until late at night seven days a week. The sorts of service commuter rail enjoys during the peak is available on rapid transit at any time.
  • Capacity tends to be increased by adding frequency, but can come from longer trains once high frequency is already reached.
  • Connections are utilised for coverage and branching of lines is uncommon. Lines generally have the same frequency along their length and people need to connect from one line to another at transfer stations to get to different destinations on the network. The requirement to change trains to get to certain destinations is offset by the much shorter wait times that single frequent service patterns provide.
  • Rapid transit often has through-routed “pendulum” lines. Most lines pass through the CBD rather than terminating there, while some may not enter the central city at all. A through routed line give roughly double the number of potential direct destinations as a line that stops in the CBD.

    Singapore rapid transit. Through running crosstown lines, interchanges and almost no duplication or branching.
  • Single consistent service patterns. No peak specials, expresses or skip stops. The ability to shave minutes off the trip downtown is forgone in favour of regular and dependable all-stops service that anyone can use to get anywhere. The stopping pattern at 11pm on a Sunday night is the same as it is at 8am on a weekday morning.
  • Trains can be set up with more standing and circulation room on board and more doors per carriage. This comes at the expense of some seating but allows more capacity overall and facilitates a high turnover of passengers at each station.
  • Timetables and route maps tend to be very simple and easy to understand. Timetables often don’t list individual services but just outline the frequency and span (“The blue line runs every five minutes from 7am to 8pm”).

In short, rapid transit relies on connections and regular service to allow people to travel whenever and wherever they want with a minimum wait time. It allows people to rely on the rail system for all sorts of travel, not just their regular city commute to work.

 So which is better?

Reading this post you can probably see a tinge of bias against commuter rail already, and to be perfectly honest I think it is warranted. I’ll leave you to make your own decisions, but I’m happy to come out and say I think a rapid transit “metro” style service model is the one we should plan for in Auckland.

My thinking comes down to a very basic line of reasoning. Rapid transit serves many trip types and destinations well, but commuter rail only serves commuters well. The deal breaker in my opinion is the fact that a well designed rapid transit network can serve commuters just as well as a commuter rail system, but a commuter rail system will fail to effectively serve a wide range of origins and destinations at various times of day or night.

Commuter rail is great if you make just one return trip a day to your job at the same regular time, and you’d like to do that as quickly and comfortably as possible. But it’s not very good if you try and use if for other reasons: to shop, to visit friends, to get to sports practice, to go to the movies, to make a date (and keep it!) regardless of the time or day of the week. I would also argue that commuter rail might not actually be so much use to office workers these days. Modern commuters have varied start times and varied responsibilities, they can often work across different sites, start at different times, work late to finish projects, have meetings all over the city, attend after work functions and come in on the weekend to get reports finished off in time.Commuter rail lacks the frequency, connectivity and span of service to make spontaneous trips where and where you want them. In a nutshell commuter rail doesn’t give you the same car-like freedom of rapid transit.

The reason for this stems from the fact the commuter rail has a very narrow set of goals and objectives. Our rail systems in Australasia tend to follow this narrow focus for two reasons, both of which are somewhat artificial.

The first is that our funding and evaluation mechanisms are framed in terms of road traffic decongestion, in particular weekday peak traffic. Commuter rail is appealing to peak time commuters so it is easy to justify it as a means to bleed traffic off the motorways, in particular longer distance commutes from the outer suburbs. Indeed, many of our public transport models only every consider peak hour travel, and the outputs are often judged in such useless terms as ‘cars taken off the road’ or “minutes saved by motorists”. It could be very hard to fund a rail proposal that moves a lot of people around at off peak times, simply because if the roads aren’t congested in the off peak there is no decongestion benefit to be had. In short, rail can only be considered worthwhile and funded where it relives peak CBD focussed travel, which means we get the commuter model funded.

The other reason is a little more contentious. I believe that commuter rail systems are favoured in our part of the world because our decision makers never take public transport. Because all our politicians and executives drive, they are predisposed to service patterns that most replicate their expectations for travelling by car.  That is to say they focus on vehicle speed, personal comfort and system capacity, the things that are salient when you travel in your own car.  What gets lost is any understanding of span of service or frequency. How do you explain the enormous value of very frequent service to a person who never has to wait even a second to get in the drivers seat of their chosen transportation. How do you discuss span of service with someone who can take their car out of the garage at any time of day or night, seven days a week?

There is a discussion to be had here around economics. On one hand there are undeniable benefits of relieving peak hour congestion and there is the simple fact that our CBD couldn’t grow significantly without more rail access. But there are big inefficiencies with a focus on the CBD peak, the main one being that you require a large amount of infrastructure and lots of trains to operate at full capacity only a few hours a day, five days a week. Outside of the peak all that sunk investment sits empty and unused in the stabling yard. Also the CBD peak is a finite sized market, one that is already relatively well served by public transport and doesn’t have a huge potential for further patronage growth. So what is so wrong with this? Well it leaves us with a system that is expensive to operate, but one that also has a self-limited ability to pick up new paying customers.

The rapid transit model on the other hand utilises much more of that infrastructure and vehicle capacity right across the day and the week, and furthermore it doesn’t limit the market to central city destinations or peak commuter times. While it has a higher operational cost than commuter rail, it also has a much larger pool of potential customers. If done right, rapid transit can be much more cost effective.

 Can we have best of both worlds?

While I think the rapid transit model is the way to go, I can’t ignore the commuter rail basis of our existing network and the demand there is for peak hour travel to the CBD. It seems that a hybrid model might be ideal, a commuter rail system that operates like a metro with a regular all day service pattern and high frequencies in urban areas. Something that works like suburban rail in Swanson or Pukekohe, but runs like rapid transit through New Lynn and the central city. Luckily there are such systems abroad that we can use as an example, including the German S-Bahn and the French RER. These are effectively commuter rail systems that have been linked by underground tunnels in city centres, and upgraded to metro style frequency, span and stopping patterns. Sound familiar?

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6 comments

  1. The person who wrote this is clearly ignorant of the fact that you can have a commuter rail and metro system hybrid that does not require long trains or two drivers. This is the fact of the Vancouver Canada Skytrain system which is driverless, operates every 7 mins during peak times and moves over 500,000 working commuters per day, while still allowing tourists and local people to use it for shopping and visits to family. It can also be scaled as suburbs grow outwards and is clipped on to the side of all bridges in the Vancouver region. It is also electric.

  2. Both the models work better when the population is densely focused around stations. For example only a small percent of the North Shore lives within 800 metres of the Northern Busway stations. This means when people get off public transport from the CBD they are likely to look for motorised transport. If the bus only comes every 15 minutes a car can appear a better option.

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