Raiway PW question: double slips

[drivin_me_nuts]

Perhaps someone here can answer my question on PW.

Are double slips still installed on mainline routes and if so, do they have moveable frogs and mainline speed limits?

Cheers

[Ross1988]

I work on the railway, but only as a surveyor, so not massively up to date on the P-way stuff, Sorry.
Although I have little to no idea what your asking, can someone explain as a matter or interest?

Cheers!

[Pigeon]

There are certainly still some in existence but I very much doubt any new ones are being installed.

[ymwoods]

Pigeon said:

I very much doubt any new ones are being installed.

Something wrong with them?

[Pigeon]

Complex, harder to maintain, larger component inventory required; greater risk of derailments than "conventional" simple turnouts, and harder to adapt for high speeds.

The same routing functionality is provided by two simple turnouts placed toe-to-toe, but without those disadvantages.

Simple turnout:




Pretty well the only advantage a double slip has over two turnouts toe-to-toe is that it is shorter, so they are only really useful in confined spaces where speeds are low, such as yards and station approaches.

[ymwoods]

Ah ok thanks!

A few of the older stations near me have these so I was just wondering as I use them now and again

[useyourdellusion]

Pigeon said:

There are certainly still some in existence but I very much doubt any new ones are being installed.

I've never heard them called that before tbh. We know them as 'switch diamonds'.

They are very tricky to tamp. The sleepers/bearers are all at odd angles to eachother, making it difficult to lift the rail and get the tines in the ground effectively without striking anything we shouldn't.

They normally end up being jacked and packed with Kango's filling in where the tamper had to miss.

Hardly ideal really. I'm not surprised they're being phased out.

[spitfire-ian]

There were quite a few at Newcastle



Although not anymore it seems...

[mrmaggit]

Well I can see two in that picture!

[jackregan]

a few years back there was a double slip at stourbridge juntion, just next to the chiltern sidings! nearly as rare now as three way points!

[Ross1988]

Ah switch diamonds. Still use them in republic of Ireland. But don't know if there being phased out.

I did know, just never referred to them as 'double slips' although I do only see them on old infrastructure.

[sniff diesel]

Still a lot of them at New Street station.