Original text as sent to Chronicle:
John Carson makes a number of useful and insightful points about the difficulties buried utilities can create for tram re–installs.
However they are not not as great as he implies. Edinburgh Tram was based on a heavy, sleepered rail system and trams, and these impose pressure at a far greater level on buried service than do the floated beam type tracks and the light rail vehicles we are proposing. Thus Edinburgh required deep excavations and full service re-location but beam tracks generally do not require utilities to be relocated per se. Floated beam type tracks impose less pressure at the bottom edge of the beam than does a single wheeled bus and thus will preserve the vaults and underlying services which do not need to be moved.
John also thinks that you have to close a tram line when it is being worked on – this is not true. There are three options:
Because trams generally operate at 6 minute interval strictly on time, it is easy to arrange two trams to arrive simultaneously from either side of the excavation and work in shuttle mode, with passengers having to make a short foot journey between trams.
In the continent it is commonplace to see trams moving slowly over deep excavations, suitably supported so there is no need to close the line – I myself have witnessed this in Antwerp 40 years ago. ( photos on BathTrams.uk website)
A third option is the use of temporary ” kletterweiche” tracks which are laid to one side of the excavation to deviate the route temporarily, and which cars can also traverse
John is absolutely right about the need to identify services before hand, and if he would care to look on the Bath Trams website he will see this point is well covered and understood, and we have some of the UK leading experts in this area of consents and approvals on our Board. As has been pointed out, one of the principal causes of the problems in Edinburgh was the failure to carry out a proper survey before hand.
I would also point out, that the original letter mentioning Edinburgh trams did not say it was a good example, but it cited
a) that connecting it to a park and ride vastly increased the patronage of the park and ride compared to the previous bus connections indicating that drivers will switch to trams, and also b) that usage had dramatically increased and now exceed projections. ie it makes the point that trams are enormously attractive to car drivers, whereas buses are not.
As regards trams pushing traffic out to the periphery this would not be true in Bath. We are not generally proposing segregated routes for trams in Bath except there may be one or two such as the centre of Wellsway, which will not impede car traffic. We propose a radial spoke and hub layout, and experience shows that car drivers will use trams, whereas they will not switch to buses, and with a 6 minute service it will be quicker to go in, and then out by tram,rather than trying to fight the across town traffic in a car. And this also applies o the school run, where parents will be happy to send their kids on even two tram journeys because trams are so frequent and reliable compared to buses. Thus there will be little need or pressure for car drivers to cut through the peripheral areas.
Dave Andrews BSc. C. Eng. M.Inst.E