1Model rail gradients

Mod­el rail­ways, like the real thing, tend to be fairly flat.  If you want ot have more com­plex lay­outs with gradi­ents you need to plan care­fully in advance, and avoid the tempta­tion to cre­ate an unreal­ist­ic (and undrive­able!) incline.

Many mod­el­lers wish to build mod­els that look real­ist­ic, so let’s start with what sort of gradi­ents are found on the real rail­ways.  The Wors­brough incline on the former wood­head main­line from Manchester to Shef­field was a 1 in 37 incline, and reg­u­larly used 4 engines.  Parts of Mer­sey rail are claimed to be as steep as 1 in 27 as is the Middleton Junc­tion to Old­ham Wer­neth line.  More sus­tained gradi­ents include examples such as around Ports­mouth where the line from Goldalm­ing to Haslemere has a gradi­ents of around 1 in 80.  The Lickey incline near Birm­ing­ham is a 1 in 38 incline for 2 miles.

Put anoth­er way, short inclines on the real rail­ways have been as severe as 1 in 27 (3.7%), but these required spe­cial bank­ing locos or mul­tiple locos.  The steep­est sus­tained inclines that are oper­ated without spe­cial locos don’t exceed 1 in 80 (1.25%)

To cross over tracks with 00 gauge requires a height of 60mm from top of track, to bot­tom of base­board above.  With a baseboard+track thick­ness of 10mm this means to cross one track over anoth­er will require a rel­at­ive height dif­fer­ence of at least 70mm.  Achiev­ing this in the shortest dis­tance can be achieved by 1 track sink­ing 35mm and the oth­er rising by 35mm.

With a real­ist­ic incline of 1.25% this requires a length of 2.8m!

Unless you have a lot of space it will be hard to build a lay­out with a cross over that sticks to real­ist­ic real world inclines.  So the next ques­tion is — what is the steep­est incline that can be oper­ated suc­cess­fully with typ­ic­al 00 gauge locos, and is there any­thing that can be done to improve this.

Users on the hornby for­um sug­gest that around 1 in 75 seems to be the lim­it for a 6‑coach train. Anoth­er recom­mend­a­tion is around 1 in 60. This can be pushed to 1 in 50 with short­er trains, but with full length (8−10 car­riage) trains pulled by steam locos any­thing steep­er than 1 in 50 is unlikely to work. Using the same for­mula as above the length required it still 1.75m. Anoth­er good sum­mary is Mod­elRail­way­En­gin­eer.

Can we improve this

One way mod­el­lers have improved loco grip in the past has been to increase loco weight. This has the obvi­ous down­side of increas­ing the weight that the motor has to pull up any incline, and there is often lim­ited space inside locos to fit weights. I recently wondered if it would be pos­sible to improve the grip of locos by pla­cing a mag­net­ic mater­i­al under the track and using super-strong mod­ern mag­nets (cheaply avail­able from ebay) in locos to improve grip. Well — it turns out it is — and there is already spe­cially designed kit called Powerbase being sold for exactly this pur­pose. DCC con­cepts guar­an­tee that Powerbase will double the pulling power of locos up 1 in 30 gradi­ents, but what will your locos pull up those gradi­ents to start with, and how much will powerbase help with a 1 in 50 incline?

One test of powerbase found a 2−6−0 loco on a 1 in 35 gradi­ent improved from pulling 8 wag­ons to pulling 29 wag­ons and could have done more.

Anoth­er example of the improve­ments avail­able was recently in the Hornby magas­ine. On a 1.5% incline (1 in 66) almost every loco tested doubled what it could pull, with smal­ler 0−6−0 and 4−4−0 locos able to pull 6 or 7 car­riages, and lar­ger 2−6−0 and 4−6−0 locos able to pull 12+ carriages.

Using Powerbase it seems that inclines of 1 in 30 are pos­sible with good length trains, tak­ing the length required for such an incline to only 1m.

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gravatarTony Hill

Very clear present­a­tions and use­ful links to my favour­ite soft­ware- ‘Any­rail’ (now on Any­rail 6)