whos2091 wrote:
However, there is a limit to the capacity you can get from such a bus
service without more infrastructure (at very high frequencies, buses
will need to be able to overtake each other easily). Longer vehicles
will be needed (longer than the current bendy buses) - and that brings
us right back to trams or tram-like technology (e.g. optically-guided
multi-articulated buses).

As a daily user of the 207 or 607 route, I am obviously supportive of
the tram. However I have been surprised, when talking to people, about
the strength of local opposition. Moreover, the more I use the route,
the more I feel that some quite cheap measures (a few more bus lanes,
some prioritisation at lights, better management of the driving
schedules) could be put in place within 12 months to really speed up
the bus routes on the Uxbridge Road. I would suggest that the project
should be put on hold for 18 months while some other measures are
tried.

I have read again and again about the impossibility of putting more
buses on this route and I simply do not believe it to be true.

Perhaps not now; the whole point is to cater for future growth in both
car and public transport traffic. There are some extremely large
developments coming in Southall (gas works) and Shepherd's Bush (White
City), bringing both residential and employment growth along the corridor.

Whilst further bus priority measures might improve capacity now, there
is a practical limit to how frequently you can run buses along this
route. I suspect buses are *already* prioritised at some lights along
this route as part of the SCOOT traffic control system - however, users
often don't notice the prioritisation because it works by juggling green
time for each arm at the junction, rather than by always letting
approaching buses through without considering the queues building up on
the other arms of the junction.

An ultra-high bus frequency - to meet the demand predicted on this
corridor in 10-20 years' time - would need much more forceful signal
prioritisation to prevent excessive bunching-up of buses. In turn, that
prioritisation will cause big queues to build up on roads joining or
crossing the Uxbridge Road - which in turn will impact upon other bus
services in the area.

This is the same problem magnified for Cross River Tram. Bus-based
proposals for Cross River were ruled out because the higher frequency
required to deliver the same service was impossible to get across major
east-west routes in central London (Holborn for buses, Euston Road for
cars). I recall seeing mention of 60-80 buses per hour needed to meet
the demand, compared to 30-40 trams per hour.

--
Dave Arquati
www.alwaystouchout.com - Transport projects in London