Do trams provide better accessiblity than trains?

% of metropolitan households and jobs within 400 m of a tram/train/SmartBus stop (data from DoT)

New research by the Victorian Department of Transport (DoT) shows Melbourne’s tram system provides access to 34% of metropolitan jobs, whereas trains only give access to 15% (see first exhibit). The analysis found trams also give better access to housing – 17% of metropolitan households are located close to a tram stop compared to 8% close to a train station.

DoT calculated the proportion of metropolitan jobs and households located within 400 metres of tram, train and SmartBus stops, using 2006 Census data.

The superior accessibility of trams might seem surprising given most popular discussion about public transport is focussed on trains. Moreover, trams and trains both serve the employment-rich CBD, so the difference in access to jobs is probably higher than most expect.

The department doesn’t offer an explanation, however there are logical reasons for the superior showing of trams. These include the higher density of the tram route network, the greater frequency of stops, and the relatively high employment and housing densities in the central part of the metropolitan area served by the tram network (i.e. the inner city and inner suburbs).

In the inner eastern suburbs, for example, there are nine parallel east-west tram lines between Victoria Rd and Glenhuntly Rd, a distance of just 8 km. The tram line on High St in Prahran is paralleled by another route just 560 metres to the north on Malvern Rd and one 650 metres to the south on Dandenong Rd.

As shown in the second exhibit (under the fold), tram stops are much more closely spaced than train stations. Tram stops in the inner eastern suburbs are every 200-300 metres, whereas stations in this area are usually more than a kilometre apart.

The tram network also services an area of high job density. The inner city – the area within 5 km of Melbourne Town Hall – might only have 28% of all metropolitan jobs, but they are concentrated in a relatively small area. Likewise, 50% of all jobs in Melbourne are more than 13 km from the centre, but the 0-13 km half is necessarily at much higher density than the 14+ km half.

Compared to the tram system, the train network is relatively sparse, particularly in the middle and outer suburbs where not only the distance between the radial lines increases as a function of simple geometry, but the distance between stations also increases. The distance from Narre Warren station to Berwick station, for example, is over 4 km – the 400 metre walk radius assumed by DoT accordingly misses much more than it picks up.

Suburban rail lines don’t in any event tend to be near jobs. As I’ve pointed out before, the vast bulk of suburban jobs aren’t located within large centres, but instead are relatively dispersed. Even the minority of jobs that is located in large centres tends to be spread out over a relatively extended area rather than concentrated within a small and neat 400 metre radius.

Clayton is by far the largest concentration of jobs within Melbourne’s suburbs, yet very few of the jobs it contains are near a rail station. The second largest job concentration in the suburbs is Tullamarine, which isn’t served by rail at all. The high proportion of jobs accessible by SmartBus services signals clearly that most suburban jobs aren’t within 400 metres of a rail station.

But providing potential access to lots of jobs is not the same as actually delivering workers to them. Trams might be within 400 metres of twice as many jobs as trains, but the latter nevertheless carry well over twice as many commuters to work each day as trams. There are a number of reasons for this difference.

One is that the assumed 400 metre walk distance is harsh on rail. Commuters are prepared to walk further to their nearest stop if the overall journey is long. As rail work trips are on average much longer than tram trips, the assumed walk distance to a station is too restrictive – a distance of 800-1,000 metres would be more reasonable.

Another reason is that many more train travellers get to their train station by other motorised modes – principally by car, but also by bus and tram – than is the case for trams. In fact half as many train travellers combine motorised modes as simply take the train direct. In contrast, the number of workers who use another motorised mode to connect with a tram as their main mode is quite small.

Probably most importantly, taking a tram to work is slow. Trams stop frequently and, because they don’t have their own right of way for much of the route, get caught in peak hour traffic. Commuters who have a choice will take the train instead, either driving to the station or using a bus or tram to connect. Another factor is that many inner city and inner suburban workers are on high incomes – rather than take a slow tram, some will get a car and/or a parking space as part of their remuneration package and will elect to drive instead.  Read the rest of this entry »