In Geneva, Switzerland I noticed that car traffic is right-handed as well as bus traffic. Obviously buses and cars wouldn't drive on opposite sides of the road. Here, though, there is also tram traffic, which runs concurrently with the buses, making transfers and exchanges quite simple and easy.

This all seems logical, so far.

What threw me off was that it seems that trains seem to travel as left-handed traffic.

Do trams and trains have set left- and right-hand traffic?

Should it not match car traffic? Does it not matter?

Are some places different than others?

closed as too broad by Tor-Einar Jarnbjo, Ali Awan, Dmitry Grigoryev, David Richerby, Itai Feb 4 '18 at 18:54

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    On reddit I found this nice map showing the side trains drive on. Note that it doesn't match the side for road traffic in many places. i.imgur.com/E59G7xM.png – asdfex Feb 4 '18 at 14:57
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    I wonder why Iceland even has a color on the map @asdfex found. – Henning Makholm Feb 4 '18 at 15:18
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    @asdfex Yes, but it's more complicated than that. In Paris, the metro is on the right hand side, but the RER is on the left hand side. In Budapest, the metro and three of the HÉV lines are on the right hand side, but the Gödöllő HÉV line is on the left hand side for some reason. These suburban (no-toilet) rail lines are usually separated from the large component of the railway lines in the country, so it doesn't cause a conflict that they run on different sides. – Zsbán Ambrus Feb 4 '18 at 16:41
  • Voted to close as too broad but I think this is off-topic, too. Whether the trains/trams run on the left/right is of essentially no consequence to the traveller. – David Richerby Feb 4 '18 at 18:29
  • @HenningMakholm Guess the data is historical: en.wikipedia.org/wiki/Rail_transport_in_Iceland – helm Feb 4 '18 at 18:52

Here an answer from personal experience.

Tram traffic mostly follows the rules/side of road as the road traffic they ride between, but exceptions are possible.
Train traffic does mostly have a preferred side of the track but does not always follow road traffic.
Mostly train preferences are by national network, but not all the time. A country where the national network is made up relatively recent out of several smaller networks, like in Switzerland, each network may follow its own rules and only meet at stations, you can just not be sure.

In both cases there are big exceptions, where only one side of the tracks may be used for whatever reasons. (From damage or work to just the track giving a better view on a difficult spot to animals along the tracks.)

From my home window I can see a factory rail line (double track) which connects with the national rail network a bit father down.
In the past the trains on the factory rail line (outside the factory boundaries here) would keep to the right hand side of the double line. After a prolonged period of work on them, they switched to whichever side of the line that seems best for that time. Which is quite often the left one of the double set.
A bit further down the tracks they meet up with and join a track coming in from the national rail network, going on as three tracks side by side and you can expect trains either directions on each of the three sets, ie all going west, all going east or anyone going opposite to the other two. As this is a small network, the operators (control room) is likely more flexible than a national rail network, but I have seen this kind of situation in a much wider setting as well.

So never assume any rail traffic to be on a given side, always look, listen and look again. And of course, follow any signs.


To answer your direct question: No, it doesn't matter whether trains run on the same side as road traffic in the same area does -- except, of course, for trams that run mixed with road traffic.

It doesn't even matter much whether trains on one line run on the same side as trains do on other lines in the network. It is less confusing for everyone if there's a consistency between different lines in a system, so usually each country has a convention anyway, but it's not as if it's unsafe to have parts of the system operate on the other side, and this does happen in some places for various reasons.

Having different conventions on different stretches of road would be a major safety risk, because all drivers would need to remember what the correct side for the particular road they're on is, and mistaking it could easily be disasterous. But train drivers don't control which of the tracks they're running on; the switches are controlled by the signaling system, which ensures that trains won't collide (unless they run a red signal) -- so there's no failure mode where trains crash into each other because one driver was mistaken about the rule of the road.

In most places the signaling system is constructed such it enforces running either on the left or on the right, unless special emergency working procedures are used. This is cheaper to build than bidirectional signaling where the signaler can choose to send any train running either on the left or on the right. In the recent several decades it has become common to install bidirectional signaling on new lines where any kind of traffic density is expected, but this is mostly for flexibility in case one of the tracks is temporarily out of service; in usual operations the same convention as the rest of the network is followed. And many existing lines still have signaling from before computerized signaling made it economically feasible to make every track bidirectional.

Some examples of special cases:

Trains run on the left in Sweden but on the right in Denmark. The two networks are connected by the Øresund bridge, and for engineering reasons the changeover point between left and right is at a flyover a few kilometers north of Malmö central station. So several double-tracked lines within Malmö use right-hand running like Denmark does.

One branch of the tram network in Gothenburg (also Sweden) is a converted railway line and does not feature any street running. The railway already had platforms between the tracks, and since the trams are unidirectional, they only have doors on the right side of the vehicle. So on that particular branch trams run on the left -- opposed to the rest of the tram network which run on the right like road traffic does.

A few short sections of the London Underground run on the right for historical reasons, or -- as in the case with the Victoria Line around Euston -- to provide covenient same-platform interchanges with other lines.

Similarly, a short stretch of the Munich S-Bahn (between Ostbahnhof and Giesing) runs on the left, because trains reverse direction at Ostbahnhof and it would be operationally inconvenient for them to need to cross paths while doing so.

Fully separate urban railways may run on a different side from the norm in the country they're in. For example the metros in Milan and Brescia run on the right, in contrast to mainline railways in Italy running on the left.

  • You could add a sentence about the Øresund connection and that it had to come up with a solution due to Danish train traffic using the right track and Swedish using the left track (Sweden never changed the trains when the switched from left to right on roads). – Bent Feb 4 '18 at 15:58
  • To add to the exceptions: in France, mainline rail traffic is usually LHS, the opposite of road traffic (this includes suburban railways, but excludes trams and at least the Paris metro). But Germany is RHS. Alsace and Lorraine (northwest France) were part of Germany when the railway networks were developed, so in that area, it's RHS. Except for the new TGV line of course. – jcaron Feb 5 '18 at 17:30

There is an extensive discussion of this in Wikipedia here and a handy table by country in which we can find that it is the norm in Switzerland for road traffic to be RHS and multi-track rail traffic LHS except for Zürich and Lausanne.

Edit in response to comments.

The article I linked to clearly states that it is the trams in Zürich and Lausanne which are RHS.

  • "except for Zürich and Lausanne" is wrong. All trams use RHS, otherwise mixing with road traffic doesn't work. And there are many more cities with trams apart from the two you listed. – asdfex Feb 4 '18 at 14:51
  • ... and at least those in Geneva and Basel I know of that are definitely RHS. – asdfex Feb 4 '18 at 17:44
  • Let's add that in Switzerland many multi-track segments are equipped for bidirectional traffic. – jcaron Feb 5 '18 at 17:33

For trains? Not really

While I can't speak to trams, I can speak to trains (at least in North America). First off, directional running is only a norm on certain parts of the North American rail network, usually older-but-still-busy lines which were originally signalled directionally but have not been upgraded. As modern signaling hardware (i.e. anything solid-state) fully supports bidirectional operation (so there's no reason not to put the lamps for both directions in, as the flexibility of bidirectional running outweighs the cost of another head at that point), modern or relatively recently upgraded lines will not have a strong preference as to which side trains run on -- in some cases (such as when an odd number of main tracks is present), the answer isn't even particularly meaningful as trains may be crossed over between tracks in basically arbitrary ways depending on conditions.

In places in North America where directional running is seen though, the common convention is right-hand (like roadways), although individual railroads or parts of railroads can, and sometimes do, use the opposite convention. It is also possible to have reversed track designations for a portion of the rail line (where while all eastbounds use Track 1, Track 1 starts off on the south side of the right of way then crosses over partway through to be on the north side of the right of way), which can introduce further confusion to the issue. Of course, it's possible both during and outside of construction works for trains to be issued authority to run "wrong rail", or in the opposite direction of the signal system, so be alert and always look both ways for both the first and the second train!

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    "As modern signaling hardware (i.e. anything solid-state) fully supports bidirectional operation" A signal lamp only points one way so, unless signal heads are installed pointing in both directions, the fact that the computer control system could cope with bidirectional running is moot. Frankly, the setup you describe sounds very unusual. In the UK, if track is doubled it's precisely because there's significant traffic in each direction, at which point having the tracks be bidirectional gives very little advantage (and risks head-on collisions when stuff goes wrong). – David Richerby Feb 4 '18 at 18:25
  • @DavidRicherby -- bidirectional signaling gives much more flexibility (not only during irregular operations, but with the handling of work events or loading gauge limits, especially when you have split rights of way) – UnrecognizedFallingObject Feb 4 '18 at 18:32

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