Why trams not buses are the backbone to most low traffic and congestion cities
It is worth explaining the fundamental engineering differences between a steel wheeled light rail or tram and a rubber tyred bus (whether battery, trolley, diesel, or electric, Chinese Zhouzou tram bus) and why trams are nearly always the essential backbone in any successful low congestion city transport mix which will of course include buses for the feeder and peripheral routes. There has to be a reason why all clean cities, both historic and modern are generally built around a tram network, not buses.
From the driver in the car’s view point, only railed vehicles are an acceptable alternative to some car trips, typically shorter journeys in towns; buses are not. The evidence for this is clear, from the busways built in Britain since 1970, from Swansea which spent £10m on road alterations and new super bendy buses but soon abandoned them, and from Utrecht, entirely car free in the centre, which is replacing its super triple bendy bus with a tramway. Other busway failures listed here:
Tramways are expensive to build, last a very long time and have lower operating costs than buses. So the marginal cost of carrying extra passengers is very low. The London Underground demonstrates this daily. This is why trams can operate throughout the day at 6 minute intervals 2 minutes in Budapest. There is little benefit in leaving them in the depot, and a frequent service throughout the day is what car drivers want, to encourage them to leave their motors at home.
On the other hand, buses of all types (trolley, bendy bus etc.) are more expensive to operate, because the high cost of the driver is shared over fewer passengers and they have short lives and expensive tyres, brakes, etc to wear out. With bus passengers ‘captive’ the result is an infrequent and slow service with long stops for passengers to alight and board, compared to multi-door trams, and the need to compress passengers close together in bench seats
A tram is more like an underground train and it is perfectly acceptable to stand near the doors and move around, because there is no jerk or bus vibration. This ability to stand and move nearer the door before stopping, coupled with a tram having several sets of large doors means tram boarding times are shorter than a bus. So trams run at greater speed and are more punctual which are attractive to motorists and the operators. Typically trams have an operating speed about 50% faster than buses, and as fast as cars when time for parking is included. Trams are not constrained by the need to accommodate suspension and large wheels, and as a result can have exceptionally low ground clearance assisting elderly, pram and wheel chair users.
Because each tram can have up to 400 passengers, compared to a bus with around 70, and with rapid boarding and alighting a tram line can have up 4 – 5 times the capacity of the equivalent bus route.
Another important point is the granting of priority to trams. Highway authorities are unwilling to grant priority to buses because they get too many complaints from the influential car lobby. On the other hand it has been shown that a significant proportion of tram passengers are also car drivers. For the same reason Green Wave traffic light priority can be applied to trams permitting quick movement through traffic. This cannot be applied to buses, because it would require 5 times as many traffic light interruptions, and there would be simply too many light interruptions to be feasible – each bus would mutually interfere.
People in Bath are environmentally conscious. Being in a deep river gorge concentrates toxic traffic pollution in the centre of the City. Much of this pollution comes from heavy diesel vehicles like buses. NOx and small particles are killers, and over 100 people a year in Bath die from traffic air pollution diseases. About half the small particles come from tyre, tarmac and brake dust. Rubber tyred vehicles with electric motors will still exceed the WHO safe air standards limits.
There is strong evidence around the world and in the UK to support the claim that buses do not attract car drivers (all well referenced on the Bath Trams website), but perhaps the most convincing is what happened when trams were removed from Liverpool, Sheffield and London (in London replaced by trolley buses). In all cases there was an immediate drop of 30% in passenger numbers because the bus service was not an acceptable replacement, and found other means of getting about – typically purchasing a car. A more recent example is how successful Freiburg has been using trams compared to York, both historic cities of about the same size. A recent study found that only 29 per cent of travellers in Freiburg were car users, compared to 52 per cent in York, and public transport use was 18 per cent in Freiburg compared to only 8 per cent in York.
The ‘flexible’ bus failed cities as ex tram passengers swamped roads with traffic congestion. Fixed 40 year trams give confidence and permanence for people to run their lives, maybe not have a car, and for developments to be attracted to the line. Furthermore the investment can be recovered over 40 years, giving future users the opportunity to pay their fair share. Thus Lawrence Sanders’ letter is wrong is in claiming that the flexibility of bus services is a good thing, for it is obvious from the Bath local press that bus routes change frequently or are withdrawn to suit the operator. No developer plans to build a business or a housing estate based on a bus service. Tram lines are fixed for the future, and this is attractive to developers and house owners. Houses near a tram line increase in value (20% in Croydon) because the tramline is inflexible and permanent.
This is why many of the suburbs of Bath such as Twerton and Oldfield Park were originally provided with a tram by the developers – specifically to make them attractive. It’s the same reason the Metropolitan Line in London was built by the developers who turned farmland into ‘Metroland’. In fact nearly all large cities expanded along tram lines.
