Thursday, May 10, 2007

Disruption communications

Many things must happen before a train can run. The service which forms it must arrive on time. Its driver needs to be in position. The line ahead must be clear. Points must be set. Boomgates must come down. Signals must work. The doors must be unobstructed so they can close. Pantographs need to make contact to supply power. Motors must work. There can't be any errant drivers or suicidal people across the tracks. Finally the brakes must work when the train reaches the next station. This process repeats itself twenty or thirty times on a single trip.

In reality there are many more steps than the sequence above. Even if the certainty of each step being successful was 99.999%, it does not take much for one not to happen and for delays to ensue. For all the heavy machinery involved, train systems are very fragile. That makeshift plank and string in the last post is robust in comparison. Trains differ from buses, which are self-powered, can overtake disabled vehicles and, subject to traffic, can be brought in easily.

Train disruption management has been in the news lately. An article in yesterday's Herald Sun has the Minister pledging improvements for passengers. These include better communication between train control and stations, platform staff and upgraded information systems.

The diagram below shows a typical disruption. Though an incident may have occurred at a particular location, trains are restricted how close they may operate to it. An accident at a single location may see trains replaced by buses for 5 kilometres or more either side.

With the lines marked with X out of operation, use needs to be made of buses. Depending on location, this can either be regular bus routes or special rail replacements called in at short notice. The time of day the disruption occurred can also be critical - buses are least available during the morning peak as many are used for school service. Buses are easier to get at other times, though at peak times traffic limits their speed and thus capacity. Regular routes are running anyway and if they are sufficiently direct, frequent and run to a station where rail services are operating then these can ease some of the load.

Staff coverage at as many stations as possible is important. This is easiest during the morning weekday peak where staffing is at its highest (including at some usually unstaffed stations).

The Herald Sun article suggested hand-held radios as a possibility. These may indeed have some use, but it depends on who staff will be able to talk to. Train drivers and Metrol use an analogue-FM communications system in the 400 MHz UHF band. Bus companies use similar systems on other UHF frequencies.

The cheapest UHF-CB radios operate on other frequencies again, so are incompatible with either Metrol or bus radios. These radios have a range of around a kilometre. Hence their primary function could be to allow communication within a station precinct (eg between a train platform and the rail substitute bus stop 200 metres away on the other side of the track). However where stations are sufficiently close and are unobstructed from one another they could also provide limited contact between them.

Before a decision is made on this, we need to consider communications needs in detail and other technologies that could be useful (eg better use of existing station PA systems or mobile phones). This will be the subject of a later post.


Daniel said...

Real life example on Thursday 17/5. No SMS alerts. No advice on the Metlink or Connex web sites. Either of these would be a start, and don't require an injection of funds to employ more staff or supply more equipment.

Melbourne Tram Driver said...

I've often considered this, but why not have a public transport radio station that has access to tram, train and bus activity? It could be broadcast at stations and stops on a particular frequency so that anyone with a radio could tune in and see what's going on.