Trams can get through traffic faster than buses or cars without lane segregation

Trams can share road space with cars without being delayed – have a look at the above video – you will see the trams streaming along, with no cars in front, but a queue of cars behind….

There are a number of interlocking reasons why trams are faster through traffic than buses or cars:

First: Trams only stop for 20 secs, because they have large multiple doors and off tram ticketing. This is not available with buses which therefore have to pull over for an extended time whilst people queue and pay and which delays and frustrates users. The bus then has to force its way back into the traffic which has passed and queued in front of the bus; whereas the tram stays in the road, holding back cars for only 20 secs which is a minor inconvenience and crucially means that there are no cars in front when it restarts.

Second: Because trams give a much better service than buses (fast, reliable, frequent, comfortable, prestigious) trams are well used, so traffic authorities will grant them traffic light pre-emption rights which they do not do for little used buses ( due to complaints from motorists about underused buses having these rights). Traffic light pre-emption means that when the traffic computer detects a tram coming, well before the tram arrives at a junction, it can pre-emptively set ALL lights in such a way as to clear the road ahead before the tram arrives  by a) preventing other cars from joining the road ahead and b) setting the several sets of  lights ahead to green to move the traffic forward; this means the tram gets a clear run when it arrives at a given junction, even without segregated roads space – it’s been done for trams in Zurich since the 70s and most other tram systems. ( but doesn’t work for buses)

 

Above – simplified video of Green Wave Traffic Light Priority – in fact it would not be applied to just the one junction, but also simultaneously to sufficient of the lights ahead to ensure no impediment to the tram progress, factoring time at stops.

For example imagine a tram approaching the Batheaston bypass / London Road junction from Batheaston – before the tram arrives the lights on the bypass slip roads are set to red to prevent cars entering the roundabout and the London Road from the bypass; also sufficient of the London Road lights ahead are set to green, so that when the tram gets to the roundabout over the bypass there are no cars on the London road, such that it may proceed at its normal speed, allowing for scheduled stops. All timings calculated by a central computer. This can only be done if the tram is on a regular well defined time schedule since the lights as far ahead as the Wellsway Roundabout may need to be set.

Note: Many people may say well let’s apply all this to buses.  For economic reasons that just doesn’t work for a number of reasons:

  • Due to the need for economy buses are cheap and cheerful and don’t last long so its not worth fitting the expensive off tram ticketing arrangements.
  • Cheap and cheerful means they are structurally unable to have large multi- doors.
  • Bus company on tight margins are constantly juggling, changing and withdrawing routes so this does not justify the installation of the complex equipment necessary for logging tram positions and the central control systems.
  • Trams are an expensive long term operation and can support the extra capex needed for smooth running through traffic and off-tram ticketing

The World Bank has this to say about traffic light pre-emption -…..”In some cases, public transport vehicles may be given ‘zero wait’ priority – this is usually only done for trams but may also done for BRT.”

World Bank Toolkit on Intelligent Transport Systems for Urban Transport

Third: Trams can accelerate and decelerate more quickly than a bus

Lane segregation

Notwithstanding all of the foregoing, there are large parts of the proposed network which could have a dedicated tram track – notably most of the London Road, and most of the Wellsway even close to the station. This would entail a single line down the centre with passing loops – this is done today in the centre of Bilbao for example a modern system and also Lisbon.

Beneficial effect on motorists

This system is in fact beneficial for motorists as it organizes them into “platoons” which can move much faster than in normal traffic, and by virtue of the tram taking cars off the road the remaining drivers have a faster drive.