Master­class: Sig­nals

Chris Gadsby and Richard Fos­ter guide you through the dif­fer­ent types of rail­way sig­nal and where they should be placed on your lay­out.

Model Rail (UK) - - Contents -

We guide you through the cor­rect place­ment of sig­nals on your lay­out.

Rail­way sig­nalling: for the lay­man, it’s a con­fus­ing web of seem­ingly non­sen­si­cal words – ‘in­ner home’, ‘outer home’, ‘ad­vanced start­ing’ and so on. And to the lay­man, there ap­pears to be no sense in where they’re po­si­tioned, ei­ther.

That’s not true, of course. Sig­nals are an in­te­gral part of the rail­way and vi­tal in keep­ing trains mov­ing safely. Their ap­par­ent com­plex­ity can be one of the rea­sons why sig­nals of­ten get left off lay­outs, but they are an es­sen­tial de­tail that ev­ery lay­out needs.

That’s where this guide will help. Of course, a sub­ject such as sig­nalling de­serves its own book and there have been some ex­cel­lent ones pro­duced over the years. We don’t have the space to get into ‘call­ing on’ or ground sig­nals but, over the next eight pages, we’ll ex­plore some of the com­mon terms and key po­si­tions so that you’ll feel con­fi­dent plac­ing them against your track lay­out. If you want to know more about sig­nalling, see the Fur­ther Reading panel on p37.

Now, we’ve been given the ‘line clear’ – let’s pro­ceed…

What is a sig­nal?

In its sim­plest sense, a sig­nal tells train drivers when they can go and when they have to stop. They are tied into sys­tems that are ul­ti­mately de­signed to pre­vent trains from crash­ing into each other.

The rail­way is di­vided into blocks and, tra­di­tion­ally, each block was con­trolled by a sig­nal box. That block al­lowed ad­di­tional safety sys­tems to evolve, such as staff and ticket, where a train can­not pro­ceed un­til it is in pos­ses­sion of a ‘to­ken’.

Then there’s BR’S Automatic Warn­ing Sys­tem and its forerunner, the GWR’S Automatic Train Con­trol, where drivers are warned of sig­nals at dan­ger by a shoe un­der the train mak­ing con­tact with an en­er­gised ramp in the track, sound­ing au­di­ble bells and buzzers in the cab.

We’ll look at blocks again later.

There are two main sig­nal vari­ants: sem­a­phore and colour as­pect. Sem­a­phore sig­nals date from the very ear­li­est days of the rail­way. Es­sen­tially, the po­si­tion of the arm dic­tates whether the train can pro­ceed or whether it must stop.

Colour as­pect sig­nals be­gan to ap­pear on main lines in the 1930s and were widely adopted by BR in the 1950s/1960s. They are the most com­mon sig­nal type to­day and most closely re­lated to the road traf­fic light. Some main lines still re­tain their sem­a­phores but Net­work Rail is work­ing hard to re­place them, so their days are num­bered. Bri­tain’s pre­served rail­way net­work is ar­guably the best place to en­joy sem­a­phore sig­nals in ac­tion..


Be­low: Colour light sig­nals are not just con­fined to the modern era. They be­gan to ap­pear on ‘Big Four’ lines in the 1930s and could be found on BR me­tals in the 1950s, in­clud­ing the rel­a­tive rail­way back­wa­ter of South Lynn, on the Mid­land & Great North­ern Joint sys­tem.


Be­low: A Class 105 DMU ac­cel­er­ates un­der an im­pres­sive gantry of dis­tant sig­nals span­ning the East Coast Main Line at Fins­bury Park in 1973.


Right: Even Bri­tain’s smaller rail­ways would in­vest in some pretty im­pres­sive sig­nalling in­fra­struc­ture. Lyn­ton sta­tion, on the nar­row gauge Lyn­ton & Barn­sta­ple Rail­way, is pro­tected by these im­pres­sive bracket sig­nals, con­trol­ling ac­cess to and from the main and bay plat­forms.

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