Passenger Train Variations.

In Germany many light rail lines operate under the U-Bahn (underground railway) banner. This stems from the notion that the importance of the former Federal Capital (Bonn) meant it should have an underground rail system, but being a smaller city light rail was the appropriate mode to suit the traffic flows.

Sometimes Americans will also use the term Trolley. Usually they will be referring to streetcars that are either original or replicas of the type of vehicle that was common in the 1920's. Some modern American light rail systems also use these Vintage Trolleys to provide tourist-orientated services over part of their system.

Nowadays double-decker trams are very rare - apart from museum lines they only exist in Blackpool, Hong Kong and Alexandria, Egypt. The fashion is for articulated single-deckers with several sets of doors located along the vehicle's length, the idea being that all these doorways will reduce stop dwell times - so speeding the service. Critics often question the wisdom of long vehicles because of their increased land-take on crowded city streets but their advocates claim that even if the articulated tram is half empty it will still be taking far less roadspace than the cars that would be using the road had the tram not been there! Some transport planners also point to evidence (obtained from double deck buses) which suggests that especially for shorter journeys passengers will shun the upper deck and this leads to overcrowding downstairs and under-utilisation of available space upstairs.

To a certain extent there is no clear demarcation between the terms tram, streetcar & light rail vehicle and frequently even transport professionals will mix terminologies in the same sentence.

"Real-time" information disply on a tram in Kassel, Germany.

Some vehicles will have a definite front end with driving controls located here only. At termini they require a circle of track to turn around before commencing their return journey. Usually these vehicles will have passenger doors on one side only.

As a contrast other vehicles will have driving controls at both ends, usually these vehicles will always have doors on both sides. Being 'double-ended' means that to change direction of travel these vehicles can either use a circle of track or a stub terminus where the driver will walk to the other end and drive from what previously had been the 'back' (this is also possible at 'reversing points' where there will be a crossover linking into the track for vehicles travelling in the opposite direction). There is a trade-off in that the extra doorways & driving controls on these 'double-ended' vehicles will create extra flexibility at the expense of passenger accommodation - especially seats.

The vast majority of light rail systems feature vehicles which are powered by means of a pantograph (or bow collector / trolleypole on a few older systems) and overhead wires, which can be hung from rosettes located on building walls, street lighting poles, dedicated masts or other means. In Britain it is a requirement that if one support fails the wire will still be adequately supported, this makes masts heavier than they would otherwise need be. For reasons of visual intrusion it is preferred when the overhead wires are simple 'single' wires but some systems use fully tensioned 'railway' type catenary, even within the street environment.

A few light rail systems use third-rail power collection (which requires an extra electrified rail laid alongside the rails used by the vehicles wheels), or even a combination of overhead & third rail along different parts of the route. For safety reasons third rail power systems are not suitable for use within the street environment as they usually involve high voltages - these typically being 600-660v dc old older systems and 750v dc on modern & upgraded systems. However, since the late 1990's there have been trials of (two rival) electric rail systems which might be suitable for street use. Both of these work on the principle that the conductors will only be 'live' when actually under the vehicle, and one of the technologies has been deemed mature enough to be used on part of the tram system which open in December 2003 in Bordeaux, France. During the 1980's an under-road inductive power system was trialed at the at the University of California, Richmond Field Station, but despite the initial trials proving successful (albeit with a minibus) developmental work seems to have stalled.

The ultra light rail British built Parry People Mover does not need overhead power wires because it features a flywheel-mechanical drive system with the flywheel being charged (boosted) at stops via a safe low-voltage third rail power supply. This would give ample power to travel typical distances between stops although for steep uphill gradients and long stop to stop distances it could be continuously fed with power in this way (providing it is running on its own private right of way and NOT in the street domain).

An alternative design possibility is to use a low power fossil fuel engine to charge the flywheel, although especially in urban areas there would then potentially be environmental / air quality issues.

The flywheel-mechanical system was chosen in preference to battery electric traction because of the high cost and weight of the batteries, plus that batteries can only be trickle charged whilst flywheels can be charged much more rapidly. In addition, flywheels have, by comparison an indefinite life and are much more effective than batteries in collecting reverse surges of brake energy (such as occurs during regenerative braking).

Another way to power light rail vehicles is from below the road surface. This concept is not new, apart from cable-systems (see below) in times past two electrical variants have also been used, and although neither are still in use today recent years has seen the development (and introduction into full passenger service) of modern variants. A significant reason for using surface power was / is to avoid the overhead wires, for reasons of visual aesthetics.

The more successful of the historical systems was known as the conduit system. This saw trams (streetcars) using 'ploughs' to reach electric conductors buried under the road surface through a slotted rail located between the two running rails. Although it worked well this system was very expensive to install & maintain - and was also blamed for creating problems with stray electric currents interfering with the subterranean utilities - especially in rainy weather when water entered the conduit.

The conduit system was extensively used in central London, New York City (Manhattan Island only), Washington DC (both USA), Paris, France and other cities. The Parisian trams were replaced in the 1930's but in the other three cities named here the trams / streetcars (at least partially) survived into the 1940's and 1950's. It is a matter of conjecture whether had any of these cities kept their faith in their trams / streetcars the conduit system might have still been in use today.

This link:- http://en.wikipedia.org/wiki/Conduit_car leads to the Wikipedia page with more information about the conduit system.
This link:- http://dewi.colinwilliams.ca/trains/conduit/index.html leads to some web pages by Dewi Williams with more information (& many photographs) on London's Kingsway subway and conduit trams.
This link:- http://dewi.colinwilliams.ca/trains/2004/NCTM/index.html leads to some web pages by Dewi Williams with more information (& many photographs) taken at the National Capital Trolley Museum, Washington, D.C.. which includes a photograph of a plough (plow) from a Washington conduit streetcar.
This link:- http://www.nycsubway.org/nyc/tracks/ leads to some web pages by Joe Brennan with more information (& many photographs) on the former Manhattan Island conduit streetcars.

The other electric variant was the stud system which featured in several cities in the late 1800's. One example was Paris, France, where the studs (standing 5mm proud of the road surface) were located every 2.5 metres along the centre line between the two running rails. For safety these studs were only supposed to have been energised when a skate - located under a tramcar - passed over them, unfortunately however they sometimes remained live when the tramcar had passed, with unpleasant results for pedestrians and often fatal results for dogs. In Britain the stud system was also used for a short time in Wolverhampton, where the 'dancing horses' become almost legendary!

In December 2003 a road surface power supply system came into use on a new tramway in Bordeaux, France, this being one of the "other cities" which had previously used the conduit system ("caniveau" in French) and having liked it local people wanted to follow the same principle again. However the caniveau was declared to be unsafe and overhead wires were proposed instead. After complaints from both the public and the French Ministry of Culture a modern-day version was developed whereby the conductors (powered rails) are on the surface with electrical power being collected by skates located under the tramcar. This system is known as "APS" or "Alimentation par Sol" (ground power). When the tram system first opened there was 12km of APS powered tramway on a network of 3 tramlines of approximately 21km in total length; extensions opened since then and scheduled to open in 2007 will raise the total length to approximately 43km, with even more extensions under consideration. Some sections of APS are located in neighbouring communities towards the outer edges of the tram system - not just in Bordeaux city centre as some sources suggest.

The power rails are typically 11 metres in length, and comprise of an 8 metre segment that is actually powered flanked on either side by 1.5 metre neutral sections. Effectively this means that when installed in to the ground the combined length of the neutral sections are 3 metres. Each tram is equipped with two power collection skates, next to which are antennae that send radio signals to energise the powered rail segments as the tram passes over them. For reasons of safety at any one time no more than two consecutive powered rail segments under the trams should actually be "alive", with variations to this seeing automated safety cut-outs being activated. These then switch off the offending power rail segment(s) - so that it/they will not switch on again - until being reset by a maintenance person. This can, and at times has, seen trams becoming stranded on unpowered sections of track.

Before use in Bordeaux the APS system was tested (and proven viable) on a short section of reserved track tramway in the French city of Marseilles. Nevertheless teething problems saw the system being so temperamental that at one stage the local Mayor issued an ultimatum that if reliability could not be guaranteed then the APS would have to be replaced with overhead wires. Although things have improved in October 2005 it was announced that 1km of APS equipped tramway is to be converted to overhead wires. Media reports suggest that if (and once) the system proves its reliability then there will be a string of other cities looking to use this power supply system. To this end, and despite the teething problems, the city of Bordeaux has agreed to help market the system - in return for a financial kickback from any future sales.

Problems have been variously described as including issues with water logging when the water does not disperse / flow away quickly enough after heavy rains and that possibly the safety cut-outs have been too quick to operate with issues about restoring power afterwards. Issues with waterlogging is not a new phenomena - for instance the British-style conduit system which was initially used in Madras, India, failed because it could not cope with monsoon flooding of the conduit.

Despite initial hopes that the APS system would be cost competitive with overhead wires - and far cheaper than the older type of conduit - it seems that the fixed infrastructure is roughly 3 - 3½ times more expensive to install and 50 times more expensive to operate. Apparently the first few years of operation saw 500,000 euros being spent annually on bus replacements for when the APS system suffered temporary failures. In addition to the cost of the street infrastructure the APS power collection skates and associated wiring, etc are reported to add about 100,000 euro to the cost of the tramcars. Because of the cost some English-speaking commentators have suggested that "APS" stands for "Amazingly Pricey System".

Bordeaux Tram Success.

In December 2006 it was revealed that in the past year the number of daily journeys on the Bordeaux tramway system had soared by as much as 26% - reaching 180,000 - this being a very commendable 90% of the projected 200,000 daily journeys for phase 1. In addition, it was revealed that the three tramlines are now carrying more than the entire Bordeaux bus system.

Also revealed is that reliability has reached 99%, which is especially significant in light of the teething problems with the APS ground power system.

APS Soundclip.

Passengers travelling in the correct part of the tramcar can hear the APS power collection shoes, this is especially noticeable at the transition points between the sections of powered rail and the neutral sections, and where they pass over the insulating joint boxes. This mono soundclip was recorded using a mobile telephone.

Click the speakers icon to hear a 630kb file named 'APS1.mp3'.
Also heard is the announcement for Bergonié tramstop.

Clicking any of the four Bordeaux images above will lead to a dedicated page showing more (and larger) Bordeaux APS images (plus more soundclips) in a popup window; alternatively clicking here will open the page in a new full-size window.

Additional images of the Bordeaux tramway and APS can be found on the Light Rail Transit Organisation (LRTA) website, http://lrta.org - - from the main index select "photogalleries", and from the country list (further down the page) select France. Images displayed include a section of APS test track (on ballasted formation where the power rail and running rails stand proud of the surface) and the pick-up shoes under the tram.

The LRTA website is always worth visiting for news and information about light rail and trams. In addition to the website they produce a monthly magazine which can be obtained at some newsagents / other retailers or (perhaps the best way) by becoming a member of this fine organisation! Membership details can be found on the website, and it is even possible to join on-line - http://lrta.org (link to an external site which will open in a new window).

APS roll-out commences...

In summer 2006 it was announced that two new French tram systems would be using APS over part of their networks. These will be Angers and Reims, with both systems expected to open around 2009 / 2010. A couple of months later another French city was added to the list, this being Orléans, which will use APS on a section of their second tram line.

Could APS be used in Great Britain?

If ever it were to happen the proposed use of APS here in Britain would pose serious legal issues - this is because the power rails would need to be set higher in the roadway than is permitted.

Section 25 of the 1870 Tramways Act, as originally enacted, requires that the tramrails be laid and maintained in such manner that the uppermost surface of the rail shall be on a level with the surface of the road and although there have been some amendments to this legislation this requirement essentially remains today. So in the event of a tramway promoter suggesting using APS here in Britain then their enabling legislation would either have to also amend other, existing, tramway legislation or it would have to include special enabling powers, with exemptions, as required. Of course some people would say that the 1870 legislation applies to the rails used by the wheels, and not power rails.... a debate which is for lawyers to discuss.

Another issue would be one of cost - getting past the British Government's very stringent financial criteria would probably prove be an even bigger hurdle than amending legislation.

As an aside, the 1870 Tramways Act made this requirement after a street tramway in London using a type of rail with a three quarter inch step proud of the road surface was found to constitute a public nuisance - although apparently a similar installation did not create a nuisance in Birkenhead. By enacting this legislation Parliament decided that proud rails constitute a greater nuisance to users of the public highway than depressed rails. It is probable that present-day cyclists, who sometimes complain of their front wheels falling into the groove in the tramrail which is used by the flange on the tramwheel to constitute a greater nuisance than a small raised flange.

Information source: Point 107 at http://www.hmcourts-service.gov.uk/judgmentsfiles/j1510/roe_v_sheffield.htm (link to external site which opens in a new window)

A bus equivelent exists too.

Although slightly off topic for this page it is worth mentioning that a roadway power system for buses exists too, although at presenmt it remains in experimental form. Electric buses are looked at in greater detail on the Electric Buses page.

In 2000 a bus roadway power system was tested with several electric buses in the Italian city of Trieste, however unfortunately it seems that the trials coincided with a change of local government - and whilst the old politicians were interested in seeing the system expanded to more routes the new politicians were not.

Perhaps at least in part this was because the trials were on one of the cities' busiest bus routes and there was some disruption, especially when it was being installed.

One specific technical problem which the trials identified was that the metal (of the power conductor) on the road surface was slippery, especially when wet.

The cable system was originally introduced to replace horse-drawn trams in an era before electric traction became a realistic proposition. The idea is that very long cables are located in conduits which are between the running rails and just under street level. The cables move at a steady speed which is controlled from (one or more) power-house(s) situated near the tracks, with the cablecars obtaining propulsion by means of a special device which enters the conduit and grips the moving cable.

The cable system was (and is) expensive to maintain. Sometimes the cables will break, halting all services on the affected section of track - although of course if the power fails then electrically powered services also suffer the same fate!

Nowadays the only surviving cablecars are in San Francisco, USA, where there are three steeply graded routes which originally survived through sheer chance (ie: they never got around to replacing them!) but are now kept as much for tourism and nostalgia as for any other reason. The last 'serious' urban cablecars were converted to overhead wire electric in Melbourne, Australia, in 1940.

The use of diesel powered trams (and even trains) within the street environment is fairly rare, but not unknown. Often tram-type vehicles which also venture on to mainline railway metals are called "tramtrains", whilst mainline railway-type vehicles which also venture on to city streets are called "traintrams".

In the USA a fleet of street-compatible lightweight diesel traintrams are used on the 34 mile (55 km) Camden - Trenton "River Line" which follows the River Delaware along the New Jersey / Pennsylvania border. Although mostly outer-suburban in nature this line does include some street running too. (not illustrated)