Modal shift ( ie attracting car drivers) is low for buses compared to trams – 0

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Evidence that car drivers will switch to trams but not buses – 2

Evidence that car drivers will switch to trams but not buses – 3

See also evidence that car drivers hate buses


The chart above is extracted from the below report by David Walmsley, Chartered Member of the ILT and a Member of the CIHT.  BSc and PhD in physics.

Bath Trams,

Nottingham is said to have 6M fewer cars per year on the city’s roads since the tram, against rises elsewhere. As NET has about 18M trips per year, 6M would represent at least 33%, if each car had only one occupant, so the real figure is probably more like 40%, and even more if the increase in car use elsewhere is taken into account. NET was designed with P+R as a major component, with over 5,000 free parking spaces.


Dave Gibson.


Comments from David Walmsley. Chartered Member of the ILT and a Member of the CIHT.  BSc and PhD in physics.

The PTEG report gives 19% for Croydon (16% drivers and 3% passengers).

It also gives figures for Manchester as 18% peak, 30% off-peak and about 44% weekend. I have done some averaging between the Bury and Altrincham lines here.
For Nottingham, it says 21% of passengers use the 5 park-and-ride sites, and I would expect it to be a bit higher when other car drivers are included.
I would take Lewis’s 25% figure. I suspect the oft-quoted 30% contains a bit of “optimism bias.”
Remember that there are also likely to be 15 to 20% of passengers making a trip they didn’t make before. My rule of thumb is “half to two-thirds of the tram passengers are former bus passengers, about half the rest transfer from car and the others are new journeys.”
Also remember that these are percentages of the numbers of tram passengers. 25% transfer from car to tram means 25% of the tram passengers, not 25% of the car journeys.
David Walmsley


Comments from Prof. Lewis LEsley:

Professor Lewis Lesley – BSc, AKC, PhD, CEng, FRSA, MICE, FCIT, MTPS) Professor Lesley spent bulk of his academic career studying how to get people to use buses rather than cars.

Croydon is actually 25% of tram passengers leaving a car at home, i.e. diverting from car to tram. The figure for all trips in Croydon along the tram corridor is 19%, since many trips including walking are not attractable to tram e.g. too short or too long.
The US Transportation Research Board (Report No. 1221) analysed 40 years of data of rail converted to buses, and a few bus services converted to rail. This study found that an average of 40% or tram passengers had switched from car, either all the way, or from a park and ride stop. The range was 35% to 45%. Of course car ownership in the US is much higher than UK, c. 750 per 1000 population v 450 per 1000 population in UK.
Above – mode shift San Diego Trolley ( = Tram / Street Car / Light Rail) From Professor Lesley.

” 2.2  pteg recently published a review, by consultants Steer Davies Gleave (SDG), of the record of light rail in the UK. The report (“What Light Rail can do for Cities”), found that UK light rail is popular, with all schemes operating at, or near, capacity at peak times. Overall there has been a 52% increase in patronage since 1999 with significant flows being carried outside the rush hours. This increase has come despite significant increases in fares, and at a time when patronage of the bus network outside London has fallen.”

3.2  This helps to explain the high modal shift that UK light rail has achieved, with about 20% of peak hour light rail users having previously travelled by car. At the weekends modal shift can be as high as 50%. Reductions in road traffic of up to 14% after the introduction of tram schemes have been recorded.

4.7  Light rail’s advantages over the bus alternative are reflected in the much higher levels of modal shift that light rail achieves. As set out in para 3.2, peak hour transfer from car to tram is consistently around 20%. This compares with estimates of between 4% and 6.5% resulting from significant improvements to bus corridors. Finally, as the SDG report shows, improvements to bus services (often perceived as potentially temporary) do not have the same catalytic effect on urban regeneration and city image that can be triggered by the tangible and permanent commitment to an area that light rail represents.

6.2  The bus will remain the mainstay of public transport provision in the city regions and new forms of guided, high quality and tram-like bus systems are being pioneered by the PTEs. However light rail has clear advantages on busy corridors where its greater capacity, speed, quality and reliability have led to far higher levels of modal shift than improvements to bus services have hitherto come close to achieving.

See also “What light rail can do for cities” by Steer Davies Gleave for PTEG (now the Urban Transport Group) and published in 2005.

You can get the full report off the UTG website:


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Integrated Transport: The Future of Light Rail and Modern … › books

The Future of Light Rail and Modern Trams in the United Kingdom; Tenth Report of Session … It was made clear that any future cost increases would have … passengers per year, of whom an estimated 3m would otherwise travel by carMidland Metro attracts 31% of its passengers from those who could have otherwise …



Comparative Mode-Shift to Quality Bus Schemes

4.33 While the effectiveness of light rail in attracting car users has been clearly demonstrated, the ability of bus-based schemes to affect significant mode shift in the UK remains largely unproven. A comprehensive study of existing schemes found overall potential passenger uplift from bus quality initiatives27 ranged from between 4.1% and 6.4% in the medium term (i.e. 3-5 years after implementation of all measures).


4.37 These responses are encouraging but, in comparison to light rail, suggest a much lower level of car transfer: • Typically, around 20% of peak light rail users have been found to transfer from car. In a peak hour, a typical system operating at, say, 6tph would have resulted in c.240 cars per hour removed from the road network. • Similarly, 20% of new bus users in a quality corridor might transfer from car and a 20% uplift in total demand might be achieved. At an overall level of service of, say, 30bph then c.40 cars per hour would have been removed from the road network.


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