--- InTramsDownUnder@..., "Noel Reed" <noelreed10@...> wrote:
>

> Hello Tony & others,

>

> I'm puzzled by your comments that signalling is of no use on a light rail

> route. All situations should be judged on the particular requirements.

>


Noel, I agree with your points to some extent and of course even I would not say that there should be no safeworking technology at all. There are some circumstances where it would obviously be needed such as single line sections.

However, looking at Europe again and going to Prague for the next example after that Poznan video, I'd like to hear your opinion of the operating practice on the two light rail lines in these videos, lines very similar in principle to the SLR and Glenelg lines:

http://www.youtube.com/watch?v=T6UmsCEtA68&feature=related
http://www.youtube.com/watch?v=a1UbJgZScNk

The only "controls" on these lines are indicators to show the state of the traffic light at the next road crossing and a caution light at tunnel entrances. Maximum speed is 60 km/h but the sections of the Barrandov line through the tunnels and down the steep grade on that tram viaduct are 50 km/h. The average speeds are very high though due to acceleration/deceleration and dwell time.

Note also that the long platforms that you observed in Poznan are not for longer trams, but so that trams can run closely nose-to-tail as I've shown before, and they can also run this way on the lines in the above videos, e.g..:

http://www.youtube.com/watch?v=tWtx6uzxWGY&feature=related

This way, a tram can enter the (60 metre) platform while another tram is still there in order to save time and close the headways. This style of operation is being designed for the new George Street and Anzac Parade lines in Sydney and I think it is correct to say that with an SLR-style ATP system this would simply not be possible. You couldn't have two trams in the same "section" at once because of forced separation.

Now this is the great disadvantage of such a safeworking system - it reduces operational flexibility and overall reduces speed and acceleration/deceleration, taking control away from the driver and slowing everything down. This in turn extends journey times and reduces the people-moving capacity of the line/system.

This brings us to the tram-as-trolleybus-on-rails (sorry Mick I couldn't resist that!). Unlike days of yore when trams ruled the roads, nowadays we have to address the unpleasant task of measuring their worth against buses. The arguments for trams include capacity and speed but these arguments are somewhat cut down when a different set of safeworking standards are applied to trams compared to buses. As I said before, imagine the SLR safeworking applied to the Brisbane busways - their capacity would be greatly reduced and they would be slowed down. But of course buses are allowed to follow each other as closely as they wish subject to the driver's trained judgement on speed, whether driving in the wet or rounding a bend in a blind cutting (when you would of course slow down). Tram drivers are also capable of driving responsibly like this.

If we don't have a level playing field on the rules we are going to have a hell of a job justifying the return of trams to Australian cities. The Brisbane busway advocates are crowing that their lines have the capacity of light rail and, if you compare it to SLR and Adelaide (but not Prague or Poznan), they're dead right. So, with an over-regulated safeworking culture, why trams?

cheers
Tony P
(who believes trams *must* be considered road vehicles to be in contention for using the roads - and bus/tram ROWs)