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Politicians and public servants have made a mess of Luas!

  • 20-03-2018 6:06pm
    Registered Users Posts: 1,667 ✭✭✭ Impetus

    One reads in newspapers of the problems of Luas trams in central Dublin, almost on a daily basis.

    Cities all over Europe – big and small use trams to get people from A to B, in most cases efficiently. Why is Dublin the exception? Zurich HB (main rail station, one of the busiest rail stations in the world – Zurich has similar population to Dublin). This station has about 12 tram lines (see map 1) that congregate around the railway station. While the lines congregate, the trams don’t – they keep moving to split second timing, orchestrated by a super-computer and the best traffic control software in the world – developed locally in ZH. The authorities also allow cars in the same street space. With zero congestion or delay for the public transport. Zurich’s government gives priority for public transport which makes it so good (punctual and reliable and frequent) that few people take their car. Zurich has long trams too, and the system gives them a precisely measured “green wave” until they have cleared an interchange, or collection of interchanges – to prevent gridlock. A small tram or bus would probably get less “green time.” The instant the tram has cleared the junction, it is made available for other road users.

    I was in Dublin a few weeks ago and took a tram from Heuston station via Abbey Street “tram interchange”, (call red T1 – red and green is not how a developed public transport system identifies its components – imagine if there were no numbers for buses in a city – one would soon run out of colours. In addition, there is very little indication on the street around the tram station in Abbey St of where to go for the connecting tram. While the colours appear in poorly drawn maps, there is no continuity of colour when it comes to the vehicles (which there shouldn’t be). At Abbey Street I connected with T2 southbound alighting at Harcourt – and the connection pedestrian pathway from Abbey to the T2 line. All it takes is small signs T1 and an arrow and a pedestrian symbol.

    Both trams crawled for most of the journey, because their momentum was broken at virtually every traffic intersection by massive time gaps affecting the pace of movement of public transport. (This issue is visible in any Irish city, with or without trams – large time gaps between phases in poorly calibrated traffic signal systems, pedestrian crossing phases with nobody using them, or all pedestrians have crossed the road, and vehicles are kept waiting needlessly on red.) Every second counts, and compounds during peak traffic periods to create gridlock.

    In Zurich, when a tram is approaching a “red light”, the tram driver does not touch the brake, even if travelling at 50 km/h – because he knows with absolute certainty that it will be ‘green’ about 2 seconds before he reaches the stop line. In other words, the traffic signal system is programmed to give priority to public transport in that city. That tram passes through the junction in a matter of seconds, without using brakes, using less energy, and the traffic signal turns ‘red’ for trams and green for vehicles, the instant the tram has cleared the junction. There are no phases or cycles in the traffic light system. Instead they have a computer that works out priorities for public transport, and looks at which other approaching traffic is next in line for priority (typically those waiting the longest, or the longest queue of vehicles waiting to clear the junction). Should another tram arrive, the vehicles will remain stopped to let the second tram through the junction, based on anticipation of tram arrival, and the vehicular traffic will be given the green light to resume its flow in about a second after the tram clears the junction. (There are loop detectors at the far end of the junction to confirm that the end of the tram has cleared it before other road users are given green).

    In Dublin, the opposite is the case, especially with the Abbey Street to St Stephen’s Green segment. At each traffic signal the tram driver has to stop and wait 3 to 5 seconds or so for the ‘so called priority system’ to wake up and let the tram through. Which is a waste of energy, braking, acceleration and junction capacity.

    Aside from delaying tram systems and creating chaos generally, forcing a tram to stop at lights, greatly increases the time taken by the tram to get through the junction, as the vehicle waits and then accelerates slowly along its journey. Junction time is precious, and is wasted by trams crawling through junctions. Trams carrying hundreds of people are delayed to accommodate private vehicles carrying one or two people – who both take about the same time to cross an intersection. The SCATS traffic light system used in Dublin is either incapable of managing trams efficiently or has been configured to operate with procrastination which amplifies delays.
    The Zurich system runs on VS Plus*, software which was developed by the technical (as opposed to the academic) university of Zurich (ETH**). It employs multiple detectors along each tram line (and vehicle only road) to detect vehicles with precision and estimate their arrival at the stop line. For trams and emergency services vehicles, the stops have been removed from the system – due to priority allocations to various types of traffic. Several Chinese and other cities have adopted VS Plus to manage their huge traffic flows.

    Thus when a tram is approaching a stop light, the first loop detector it meets causes the system to calculate the arrival time at the junction, the second loop (nearer the stop line) confirms the speed (the time taken to get from the first detector to the second), and adjusts the model accordingly. The multiple loop detectors acts as a backup to detect system failures. All the computations are made by a central computer system, which has backups in the case of failure, and cross checking of decisions to prevent accidents and optimise movements generally.

    My tram (was not during ‘rush hour’ – about 11h00 on a Wednesday) as it crawled from one stop to the next, as a result of poor engineering of the response of traffic signals – leading to a waste of road resources for both public transport and private vehicles.

    There are very few buses in central Zurich to get in the way of trams. The entire public transport system carries almost 80% of people using the central city area – only 20% use private transport. Buses feed trams and trains in the suburbs, allowing them higher load factors and in the case of trams more frequent services (typically every 5 min).

    There is no metro in Zurich – despite two attempts by city officials to try and foist one on the public. Zurich requires a referendum on any public expenditure over CHF 10 million. Instead of taking trams out to places like Clondalkin, for heavy lifting they use duplex (double deck) trains to take people to suburban locations (eg Naas and similar), which are faster and have fewer stops than trams. Eg Zurich HB to Zurich airport takes just 10 minutes – a similar distance to Heuston Station to Dublin Airport which takes 55 minutes. And there are direct trains from towns like Naas and Newbridge and even cities like Cork and Limerick which while they stop in the centre, they continue to the airport railway station. Both trams and suburban trains have buses timed to meet each train/tram and take the alighting occupants off the tram or train and close to their destination. All using the same ticket, which can be for an hour or two, after 09h in the morning, a week, month or year.

    No money wasted on RFID tickets (like LEAP in Dublin) – all the tickets are just printed on paper (technically ‘board’) or in the case of subscription tickets valid for a month or year, they use a plastic credit card type document. Random checks by ticket inspectors solve two problems – elimination of fare avoidance and taking samples of where the person using the ticket is at a point in time. This allows a single ticket document to be used by multiple independently owned transport providers and the revenue to be shared based on use of each operators’ system / distance travelled. A computer model can work on inspection samples to work out the travel patterns of a person anonymously.

    As usual, Ireland is re-inventing the wheel in virtually everything it does. This costs a fortune in design and mistakes that could have been avoided by looking at what others do – especially in countries outside the dysfunctional EU. Cities with zone based ticketing use the same zone boundaries for all modes of transport – except Ireland. Zurich canton public transport zone map – it even includes ferry boats and funicular rail.

    City centre map:
    Central Zurich tram and bus map (light blue lines are bus routes – map 1)

    Documents on the vs-plus software system.

    Statistical model:

    ETH university where the system was designed:

    Statistical model: