When the Southeast light rail line is completed at the end of this decade there will almost certainly be an increase in patronage along the Anzac Parade to CBD corridor. Whoever is transport minister at the time will point out that the number of bus plus tram passengers in the first few months after opening is higher than the number of bus passenger in the equivalent number of months before opening. They will then say that this is due to trams being faster, more reliable, frequent, and having a higher capacity than buses. The newspaper headlines will declare that this correlation has been caused by trams, and the (wo)man on the street will declare his (or her) support for trams as “much better than buses”. Except it’s not quite true.
Patronage will almost certainly be higher, and it will be caused by better speed/reliability/frequency/capacity. But only the last of those 4 (capacity) is an inherent benefit of light rail. Speed is a function of things like stop spacing, on board vs off board fare payments, and top vehicle speed. Reliability is a function of things like exclusive rights of way and grade separation. Frequency is a function of how many vehicles are available and the demand for transport along that particular corridor. All of these are just as applicable to buses as they are to trams. In other words, you don’t need a $1.6bn upgrade to light rail to achieve them.
Take the dot points on the bottom half of this table which the government uses to sell the benefits of trams:
- The first point is frequency. Ironically, frequency is actually hindered by tram’s higher capacity, as one tram is able to carry as many passengers as multiple buses, and so the higher number of buses required to carry the same number of passengers will (all else equal) result in higher frequencies for buses than trams.
- The second point is reliability. A reliable service can be provided through the use of bus lanes and grade separation at intersections (i.e. a bridge over the intersection or a tunnel underneath it). Both of these are in place in the Northwest T-Way for buses between Parramatta and Rouse Hill.
- The third point is speed. Both buses and trams are capable of the 80kn/hour top speed along this route. So the actual determinant of average speed is things like widely spaced stops and off vehicle fare payment. The former can be achieved by buses through express or limited stop services, while the latter has been achieved at busy bus stops through the purchase or validation of a bus ticket before entering the bus, and will soon be universal once Opal is introduced. All door boarding can also increase speed through reduced dwell times, but can be done on buses as well as trams.
- Points four through six could just as easily be implemented on buses
- The points on improved amenity on the right are all to do with the fact that the light rail vehicles are new. But new buses also share these features, such as low floors, air conditioning, real time information, etc.
All this leaves capacity, which is a real and tangible benefit of light rail over buses. Trams carry more people per vehicle, and as there is only a certain number of vehicles of any type that can run on a particular corridor before that corridor (road or rail) becomes congested and capacity becomes limited, putting trams on a busy corridor can increase its capacity (just as replacing light rail with heavy rail can increase capacity there). Jarrett Walker at Human Transit spoke of this concept as getting causation the wrong way round: high patronage causes the roll-out of trams, rather than the roll-out of trams causing high patronage.
Despite all this, and to undermine the entire argument made so far, the higher capacity of trams does actually allow the government to focus its attention on that particular corridor and implement many of the things mentioned earlier. For example, the new light rail line will have an exclusive right of way for its entire alignment 24/7, something that would not be possible with just buses as they require multiple corridors to achieve the same capacity. For this reason, the move to convert the Anzac Parade bus corridor into a tram corridor will still provide tangible benefits that could not be achieved with buses alone.