Light Rail Fits In

Illustrated "index page" image information:-

Both above types of light rail vehicle come from 'modern' (post 1970) systems. When choosing the style of operations for these systems the planners decided that they would use multi-segmented articulated vehicles which would only operate 'solo' / not in coupled formation.

By way of a contrast some long-time-established systems use older style 'rigid' light rail vehicles, either on their own or with two (or more) coupled together. Typically these vehicles will be used until life-expired - when they will be replaced with multi-segmented articulated trams / streetcars - although very occasionally other limitations may result in exceptions to this generalisation. For instance: in the Japanese example seen here the depôt and all platforms would first need rebuilding to accept longer tramcars - which explains why they are still building this style of LRV.

Varying 'Train' Lengths: Single, Double & Triple Unit Services

The single/double/triple-unit images come from Calgary, Canada; and show different train lengths using the same type of single articulated light rail vehicle (LRV) which is 24m (79ft) in length. Calgary is a popular city with a fast growing population, and to cope with rising passenger numbers it has been decided that the station platforms will be lengthened to facilitate the use of quadruple (4) unit trains.

In Düsseldorf, Germany, the three-unit services operate when there are major events at the cities' exhibition centre. As this camcorder still clearly implies, despite its 80.7 metre length (each individual vehicle is 26.9 metres long) sharing a public highway that is open to all traffic poses no problem.

A video showing triple unit / 3-car light rail services travelling as street trams in Kaiserswerther Str, Düsseldorf has been placed on the ‘YouTube’ film / video website and can be watched (in a new window) by clicking either the projector icon or this link - http://www.youtube.com/watch?v=_JuEVk8d4GI

Ultra Light Rail

For the lowest of passenger capacities there is something known as ultra light rail which is themed on the concept of small low capacity "cabin" sized vehicles running on lightweight (perhaps narrow gauge) tracks. "Cabin" transports are looked at on another page.

One of the many advantages of lighter vehicles such as these is that their lower axle loadings would mean that shallower foundations would be needed for the tracks, considerably reducing both the cost and the time duration of their installation. It is expected that it would cost just £1m per km to install this system (compared to about £6m for other types of light rail) making it one of the most cost effective rail-bourne technologies available.

Although the first fully working (and British built!) prototypes were built in the early to mid 1990's it was only in 2009 that the first of these ULRV's entered service on a commercial basis.

The Passenger Train Variations - Trams, Streetcars & Light Rail Vehicles page includes a look at the different types of light rail vehicle in greater detail.

The Parry People Mover features what could be seen to be the "minibus" of light rail transit, making it ideal for lower capacity routes.

These images show two slightly different variants of the Parry People Mover tramcars, this being the PPM50 in 'low floor' format (left) which is more suited to street based systems and the PPM60 in 'high floor' format (right) which is more suited for services that serve railway-style 'high floor' stations. It is in this latter guise that the first commercial service is being operated, with there being two Parry railcars replacing mainline railway trains on a short branch line in Stourbridge, West Midlands. To maintain overall passenger capacity and even cope with higher passenger demand the PPM services operate at a higher frequency than the mainline railway trains.
The image on the left was sourced from the Parry People Mover website http://www.parrypeoplemovers.com/ .

A video showing several different types of Parry People Mover vehicle on demonstration and in public service in Stourbridge has been placed on the ‘YouTube’ film / video website and can be watched (in a new window) by clicking either the projector icon or this link - http://www.youtube.com/watch?v=M28tGs253NM

Everyone knows what trains are about. And how they can operate underground, overground, over bridges, through tunnels, cuttings, etc, etc,. Light rail can do all this too. But because light rail vehicles are usually of smaller dimensions and lighter 'mass' they can also go places and do things that traditional trains would find either difficult or outright impossible.

One of these is take to the public highway and use it to travel through the town at street level, following the existing street pattern. Even though this usually requires the complete rebuilding of the roadway (to move underground utilities - ie: electricity, gas, telephone and water, so that their future maintenance will not disrupt the transports) the street environment is still one of the cheapest options.

Of course there are alternatives, such as the wholesale demolition of many buildings to create new surface transport corridors or creating new elevated transport systems, however whilst this was often done for new roads - at least until the public protests against it became too vociferous - such is not normally seen as a viable option for urban public transport. Therefore for built-up, often historic city centres the only other realistic option is to put the transport underground, however whilst this is sometimes adopted it is just about the most expensive option and therefore only done where absolutely necessary.

Sometimes Light Rail Will Behave Just Like 'Heavy Rail'

Away from the street environment and when operating inter-urban (cross country) services many light rail lines will look (to the casual observer) little different from a 'heavy' or 'mainline' railway. This especially applies to sections of route which use railway-style sleeper track with ballast and multi-wire overhead power supply wiring. Perhaps the only give-away would be if the line is unfenced, as whilst (here in Britain) this is a legal requirement for the mainline railways, it remains an optional feature for light rail.

Depending on service frequency, available space, and even available funds when the line is built, these lines may be formed of either bi-directional single track or twin track.

Sometimes Light Rail Will Behave Just Like Traditional Street Trams / Streetcars

Typically when operating in 'street tramway' mode newer light rail services will be routed via quieter roads which are either prohibited to the general traffic or intended for local access only, with other major roads taking the through traffic. By way of contrast existing (often upgraded) light rail services will use local streets as appropriate. By virtue of their having 'been there' for many years the situation is often different with these 'historic' systems.

A different type of 'street tramway' mode is where new (and often historic) systems travel through the city's central business district. In cities where street-based shopping centres still exist these will usually be pedestrianised zones where pedestrians can wander freely - including over the tracks. If motor vehicle access is required (for instance: to service local shops) this will usually be restricted to late evenings, or early mornings. Elsewhere these are often known as 'transit malls' (especially in American English) and are usually regarded as normal roads upon which there is a public transport / transit only restriction, and except when crossing the road pedestrians will be required to keep to the footpath / out of the roadway.

The purpose of street-based transit malls is usually either to provide a rapid congestion-free route for the public transports (as alternatives to building underground / subway systems) or to focus the transports on one corridor through the city centre / downtown core. Whilst these concepts are usually seen as being beneficial with respect to improving access to the areas served and creating a focus for inward investment, the 'down' side is that if the transport is too successful and the number of routes (lines) and service frequencies using these malls increases then it can result in them becoming congested. In some cities, such as Dallas (USA) and Karlsruhe (Germany) the chosen solution is to relocate at least some of the transports underground (at the time of writing neither city has actually started building works). Manchester (England) is adopting a different solution; they plan to create a second surface route using alternative nearby streets. One city which has already done this is Portland (Oregon) where the second (surface) city route opened in September 2009.

Pedestrian zones and transit malls are looked at in greater detail on the Light Rail, Pedestrian Zones And Transit Malls page.

Street-Based Segregation: One Of The Keys To Success

Although when travelling in the street environment light rail can share the traffic lanes with the other traffic it is usual, if the road is wide enough, for it to benefit from its own dedicated lanes (or 'rights of way'). The advantage of this is that it helps the service to operate reliably with the minimum of delay from the general traffic.

Where there is segregation the ways in which this can be achieved can vary - the most successful options have proven to include painted lines, raised sections of kerb or raised sections of roadway. However, light rail's adaptability to local circumstances means that the possibilities and permutations are endless, if effective they all are correct, what is important is that the other traffic is deterred - but not in the case of absolute necessity (for example: to pass a parked delivery vehicle) prevented from using the portion of the road reserved for the public transport. There are no fixed 'rules' - it all depends on the location.

The Swiss city of Zürich is reputed to have the (western world's) most successful urban transport system, with the public transports attracting over 50% of all journeys within the urban area

At its heart is an integrated network of electric street transports (primarily trams plus some trolleybuses and suburban light rail) as well as electric 'heavy' (mainline) suburban railways.

As part of environmental policies designed to protect the health of city-dwellers by minimizing urban air pollution motor buses are generally restricted to outer suburban and rural services.

Transport integration is looked at on the Transport Integration page.

Sometimes The Optimal Form Of Segregation Will Be
Along The Road Sides / Edges - Rather Than In The Middle

Examples Of Partial Segregation

Sometimes there is only a need (or roadspace) for one direction to benefit from proper segregation, so LRV's travelling in the other direction will share roadspace with the general traffic.

In situations such as Stuttgart below left traffic signals located where the light rail joins the roadway can hold back the general traffic for a few seconds to allow an approaching LRV to continue its journey without delay.

More Examples Showing Why Sometimes There Is A Need For
The Reserved Right-Of-Way To Be Accessible To Other Road Traffic

The two images above are video-stills - clicking either of them or the projector icon will download a hand-held 29 second video clip named 'Passing-parked-vcls320.mpg' which shows the action being described.

The Light Rail And Compatibility With Parked Vehicles. page looks at solutions related to on-street parking in greater detail.

Dedicated Traffic Lanes / Complete Separation

Sometimes complete separation is possible, however this is only a good idea if the roadway has two (or more) lanes. This is important as it will allow a stationary (perhaps broken down) road vehicle to be passed by the other road vehicles. Furthermore, with 'single track' roads there would also be the possibility of the emergency services being delayed because they were caught behind the other road traffic without being able to pass.

Examples Of Full 'Road Centre' Segregation

Examples Of Full 'Side Of Road' Segregation

Interlaced / Gauntlet Track And Bi-Directional Single Track

Other solutions for where space is at a premium can include short sections of either single or interlaced (gauntlet) track. Sometimes this will be done as an alternative to sharing the road with the general traffic at a location where there is insufficient width for twin tracks, other times it will be adopted for different reasons, such as to pass through a space constricted location or to cost effectively serve both platforms at an end of line / terminus station.

The principle difference between interlaced and bi-directional single track is that with interlaced tracks the transports retain their directional individuality (this is further explained below). Both impose the same restriction with respect to transports travelling in opposite directions not being able to pass each other / having to wait their turn.

Note that this section does not look at the use of single track in the context of where services travel along different streets, often times as part of a one way traffic system.

With the examples seen above both types of track occupy much the same ground width, however some of the other examples seen below use interlaced tracks which are set apart by a small distance. As ever, there is no fixed 'rule', it all depends on the location and what the track planners need to achieve.

The example above right comes from a location where there has been a railway of some sort for approximately two hundred years. Over the years the brickwork weakened and when one of the retaining walls on the other (but inaccessible) side of the bridge became in danger of collapse it was found to be cheaper to shore it up with massive concrete buttresses. Years later, when Tramlink was constructed, the planners decided that it would be more cost effective (aka: 'cheaper') to use interlaced track rather than rebuild the wall so that normal double track could be installed.

Interlaced / Gauntlet Track And Single Track comparisons

There are no fixed rules regarding which would be chosen for a location, but as a general theme interlaced track (ie: one inside the other) will be used for shorter distances and bi-directional single track for longer distances. Both occupy similar 'footprints' (land take).

• Interlaced track uses four rails, whilst single tracks use just two. As rails are the most expensive materials so the savings from interlacing track is not much less than the cost of double track. However, once laid, the track should require comparatively little maintenance for many years if not decades. Therefore the ongoing costs of regular inspection to ensure that 'all is well' is extremely low.


• By way of comparison, whilst single track costs less to install (just the two rails!) at each end of the sections of single track there need to be a set of points (in some places also called switches or turnouts) and these are also massively more expensive to procure and lay. Furthermore they may require a power supply to operate them, heating of the switch blades in areas prone to freezing, a high integrity interlocking mechanism on routes which are signalled, and other features which add to the cost of installation and ongoing use. Points also need significantly more frequent and intensive (and hence expensive) maintenance than plain track. In addition to checking things such as mechanical linkages (that they are operating smoothly, all bolts are in place and properly tightened, etc) there is often a need for frequent cleaning of dropped litter, leaf fall, etc., which might otherwise prevent the switch blades from operating properly. Especially within the street domain it is not unknown for such cleaning work to have to be done on an ad hoc-basis by tram drivers - delaying services in the process.

Therefore it could be said that 'everything else being equal' there is a tradeoff between the cost of four rails and the cost of points / turnouts / switches. There is presumably an optimal length of line where one becomes more economic than the other, so often it will be for the people who look at the financial aspects of installing the physical infrastructure to decide which will be used.

What might sometimes become a deciding factor in favour of single track is that it then becomes possible to reverse the direction of travel, for instance at a station where only part of the service continues on further. This is not possible with interlaced tracks as despite travelling over the same patch of ground the transports retain their directional individuality.

Other Reasons For Single Track

Single track is also often favoured as a way to save money when building a new line and it is felt that service frequencies will allow this type of track layout without impinging upon reliability. If need be then passing loops (short sections of double track which allow services to pass each other) can be located along the single track section. Sometimes these will be located at stations.

With bi-directional single track tight scheduling is often required to prevent a journey from being delayed whilst waiting for an approaching service to have passed through the single track. There can also be problems if ridership increases to the point whereby a more frequent service is required - but the track configuration does not allow this. It is not unknown for what seems like a 'cheap' solution to later need remedial work which ends up being more expensive in the longer run. However if lower headline construction costs are all that matter then this can be a necessary evil.

The image above left was taken at a tramstop which doubles as a passing point at the end of a section of single track bi-directional tramway. Note how the departure of service is being delayed whilst it awaits the approaching tram to clear the single track. This route was previously a little-used mainline railway branchline which operated trains at 44 minute intervals, and since its conversion to tramway passenger numbers have risen so much that at peak times overcrowding often prevents passengers from boarding at some tramstops. Increasing capacity by lengthening the trams or operating double units coupled-up would require every platform at every tramstop on this route to be made longer - which would be expensive - whilst the other option of increasing service frequency has been inhibited by the length of some of the numerous sections of single track. Apart from two bridges single track was only used on this route as an economy measure to reduce headline construction costs.

As an aside, since this photograph was taken most sections of single track tramway on this line have been rebuilt with two tracks, this was done as part of service enhancement plan that included increasing network capacity by buying more trams and operating a more frequent service.

The image above right was taken on a different branch where the single track was installed because the light rail took over one track from (yet another) infrequent mainline railway route and this was the only way to fit the two railway services into the available space. (The mainline railway also now operates as a bi-directional single track). This photograph was taken from the walkway for one of the newer 'more local' halts added when the light rail was installed. Normally passing places would be located at tramstops - as is done at a different tramstop nearby - but at this specific location there simply was not enough space. Because the mainline railway is electrified using the third rail system so extra security measures have been used to discourage walking on the track. This includes the saw-tooth style wooded planking seen at the bottom of the image.

The locating of mainline / 'heavy' rail and light rail in close proximity so that they share the same transport envelope is known as 'route sharing'. This is topic which is more fully explored on the Track Sharing & Route Sharing page.

Sometimes short sections of single track can also serve other purposes. Interlaced track cannot be used to reverse the direction of travel (aka: 'turn back') a tram. By way of contrast a single track section will have the same operational capabilities as a crossover, which is a short section of track which allows a rail vehicle (of any type) to switch from one running line to another running line - and often then travel in the opposite direction, returning to the location from where it just come.

Especially when finance is tight and every effort must be made to minimise costs, short sections of single track are located in front of terminal / end of line stations which feature twin tracks, as this avoids the higher purchase / installation / maintenance costs of either an X shaped crossover or two sets of linking tracks which face opposite directions - as seen below. The financial saving would come from the single track only needing two sets of points instead of four, plus the diamond crossing for the X.

The image seen below left was taken at a 'stub' type terminus, where the tracks end at buffer stops. Only certain types of light rail vehicle can use stub end termini, this is further explained on the Passenger Train Variations - Trams, Streetcars and Light Rail Vehicles page.

The two sets of crossover tracks seen above - right are located near to the depot and are mainly used by trams entering or leaving service, although crossover tracks are also frequently located at various locations along twin and multiple track routes because they allow trams (and trains) to switch tracks when reversing direction of travel, such as for short working or when part of the line is temporarily closed for major maintenance or some other reason.

Temporary Single Tracks - For Road / Track Works

There are times when twin tracks need to be temporarily reduced to a single track but the existing crossover tracks are not conveniently placed to be of any use and closing the line (even if only for a few days) simply to install a temporary crossover track cannot be justified - neither financially nor because of the disruption it will cause to the service. For these occasions the solution many tram systems adopt is to use portable temporary crossover tracks. In German these are called kletterweiche. There is no simple one-word English translation.

Compatibility With Roundabouts (Traffic Circles)

There are several ways in which light rail can fit in with the other traffic at roundabouts / traffic circles. These include underpasses / flyovers which completely separate the public transports from the other road traffic, joining the general traffic and travelling around the circle (part or full way - as required by the route served) or cutting a swathe straight through the centre. This section focusses on the latter two surface / at grade options.

The first images show various options for where the trams travel around the circle with the rest of the traffic. This represents a solution for where several routes use multiple roads to enter and leave the roundabout.

As many of these images show, there is frequently no real need for traffic signals to control the traffic as it enters and circumnavigates the roundabout. Instead the roundabouts can operate as they were designed to, with free-flow being the order of the day. For most roundabouts this represents the optimal traffic management solution. Many traffic planners seem to see traffic signals as some kind of holy grail whilst dismissing their potential negative side effects, which includes adding to traffic congestion and local air pollution (from motor vehicles), etc. Some form of signalisation would only be beneficial at the busiest of locations / times when congestion occurs by itself and even then only if it helps minimise possible delays whilst the tram queues to enter the roundabout.

By way of a contrast, where the trams travel straight through the centre of the roundabout some form of traffic control is required to permit the light rail to cross the other traffic flows in safety. However, as the last examples show, there is still an alternative to full and expensive signalisation of the whole roundabout.

Of course whilst travelling along (or on reserved rights of way in close conjunction with) city streets so the light rail will encounter and need to traverse busy road junctions. It is not inconceivable that the services may sometimes have to 'wait their turn' in the traffic signal phasing and / or travel through the junction at the same time as the general traffic travelling in the same direction. To minimise the delays many cities will programme the traffic signal computers to offer them priority.

To reduce the possibility of road traffic becoming confused and mistakenly following signals which are dedicated to the public transports many light rail systems use visually distinctive signals. Depending on the city these special signals may be used throughout the entire system, or just within the street domain with traditional railway-style colour light signals being used elsewhere.

This feature especially applies to new light rail systems, and if it does not already exist is often added to upgraded 'historic' systems as well.

• An acknowledgment light by the traffic signal computer indicating that it knows that the transport is there and wants to pass through the junction. This is in the form of an illuminated letter 'A' which comes from the German word 'Anforderung' and means 'request'.
• The 'stop' light - the equivalent of red traffic signals and comes in the form of a horizontal (crosswise / left-right) white bar. At least one of these is always illuminated on the signal heads.
• A 16 second countdown marker, to encourage the LRV driver to be ready to pull away as soon as told to do so (see below).
• The equivalent of amber traffic signals which comes in the form of a white dot.
• The equivalent of green traffic signals, which varies depending on intended direction of travel:-
  if turning left the symbol is an angled white bar \ (top left to bottom right),
  if travelling straight ahead the symbol is a vertical | (up down) white bar.
  if turning right the symbol is an angled white bar / (top right to bottom left).
• A light indicating which way the points (turnout/switch) is set.

The significance of the countdown timer is that this location is also a passenger stop / station, and to make effective use of the limited time slot in the traffic signalling sequencing the traffic signal computer wants the LRV driver to have the passenger doors closed and be ready to depart immediately the equivalent of a green signal is offered.

The signal heads are of course angled for clear visibility for the LRV driver - and not people standing on the footpath photographing them!

Traffic signals and light rail is looked at in greater detail on the Road Junctions, Level Crossings And Traffic Signal Priority page.

Examples Of Negotiating Steeper Gradients & Sharper Curves

More Examples Of Fitting In With The Urban Environment

Many light rail systems are located in places where during the winter snow and ice are commonplace, so they prepare for such weather! Even though in the most extreme circumstances there might still be be some disruption as a general theme it will be minimal. Indeed it is often a matter of civic pride to ensure that the transport keeps on working, no matter what the weather throws at it.

Fitting In With Urban Regeneration

Sometimes new light rail lines are built as catalysts to aid urban renewal. Experience has shown that by politicians and / or the local community installing / investing in new light rail systems in run down, dilapidated inner cities, property developers will also invest their money on refurbishing existing buildings and creating new residential and commercial developments within easy walking distance of the new transports. The often used 'buzz words' for this type of sequence of events include 'virtuous circle', synergetic developments and 'win win' scenario.

Portland (Oregon) used to known as one of America's dirtiest cities.

Now it is one of the cleanest.

The building of the MAX light rail line led to urban renewal in formerly derelict inner city streets and the creation of an attractive city square - which replaced a car park that had been rendered superfluous by the new transport.

Following this Portland went on to add several more lines to the MAX system and create the first new true streetcar service in the USA since WW2.

MAX and the streetcar are separate entities which mainly serve different streets.

The Portland streetcar bucks all the usual themes for new light rail systems, with the system being mostly on-street using roadspace shared with other traffic and only benefiting from traffic signal priority at a few locations where required to make certain turns. The streetcar vehicles are shorter and narrower than those of MAX, and at 40mph (65km/h) have a lower top speed than the 55mph (90km/h) which MAX achieves. Being at the 'lighter' end of the light rail gamut the streetcar's tracks are also of a lighter and shallower construction, having a railbed of only ^§one foot (30cm). These design features helped minimise construction costs and disruption to traffic flow and parking, but also mean that travel times are slightly longer than they would have been had the line been built to what could be seen as 'full' light rail standards.

^§Some new light rail systems double or even triple this depth, depending on the expertise / experience of the people involved in its design and construction.

Despite these apparent disadvantages the streetcar has been very successful. Costing less than US$60 million its simple presence has attracted many young urban professionals to live near to it. It has been credited as having attracted over US$1.6 billion of inward investment - something which is very unlikely to have been achieved with a bus service! Since first opening the original starter line has been expanded several times.

For the record, because some people are bound to be curious, whilst the streetcars are capable of travelling on MAX's tracks the reverse is not possible, as the MAX trains would be too heavy and incapable of negotiating the sharpest curves on the streetcar system.