Track at Heuston Station.

Bored while waiting for the next train and looking at the track layout.
What are those "third rails" located at some of the platforms (2-5) for?
Are they some sort of last chance braking system or something similar.

The_Wanderer

Deleted User wrote: »

Bored while waiting for the next train and looking at the track layout.
What are those "third rails" located at some of the platforms (2-5) for?
Are they some sort of last chance braking system or something similar.

They are called Check Rails.
http://www.thewandererphotos.com/2014Photos/November-2014/i-HkvNLZH/A

There purpose is to contain a train should it derail. The risk here being it would collide with the station canopy columns and cause a roof collapse. The check rail would gather the train towards the centre of the track. See example at http://www.thewandererphotos.com/2010photos/September-2010/i-H47cgS6/A towards the lower left of the picture.

You also find check rails over or under certain bridges, embankments and sharp curves.

The Wanderer.

Thanks for the response.
I was wondering whether that was what they were for, but thought as the track was straight derailment would be unlikely.
As you say if it did happen the risks are high,

Captain Chaos

I believe a train did derail just outside the platform area of Heuston about 10 years during the morning rush. From memory I think it was loco 210 with Mk2AB stock. Caused all sorts of problems that morning.

h.gricer

Captain Chaos wrote: »

I believe a train did derail just outside the platform area of Heuston about 10 years during the morning rush. From memory I think it was loco 210 with Mk2AB stock. Caused all sorts of problems that morning.

I remember that, the loco was actually 215 had been shunting the MK2 AB stock Captain Chaos, it was Wednesday 9th April 2003, it was pandemonium to say the least, it took 2 big Mc Nally road cranes to stabilize 215, a photo spread was in the following day's newspapers.
Regards
hg

Jamie2k9

There is a huge lack of consistency in where check rails are placed, how do IE decide where they go.

One example they are located over over/under Motorway bridges in Dublin (M50) however since the motorway network was completed across the country not a single check rail has being put in place. Would think the M7 in Kildare is as impotent as the M50!

Another place is the river at Monasterevin, for lines at 100mph, yet they are located over a river at Mallow around same height from ground with trains barly doing 25 mph.

goingnowhere

It depends on clearances

The M50 bridge is below standard for current clearances, so a mechanism is required to contain the train as to avoid striking the bridge

GM228

goingnowhere wrote: »

It depends on clearances

The M50 bridge is below standard for current clearances, so a mechanism is required to contain the train as to avoid striking the bridge

If the bridges are straight they usually don't require a check rail, but curved bridges do.

GM228

BoatMad

My understanding of check rails, is that they are used to prevent flange climb on sharp curves. They are not specifically of use after a derailment to " contain anything"

IN normal running the 1:20 offset of the rail and the cone profile of the rail wheel, mean that the wheel flanges never normally comes in contract with the rail, even on normal corners. However on tight corners, there is a risk that the geometry pushes the flange into contact with the rail ( opposite to the check rail ) and a risk that the flange would climb the track. The check rail prevents this by constraining the lateral movement of the axle. Its exactly the same as the check rails at points in that regard


in modern installations at terminus stations, a check rail on a straight length of rail greater then the longest carriage is installed so that any trains colliding with the buffer stop does so perpendicular to the stop and the check rail is to prevent wheel jump.

BoatMad

goingnowhere wrote: »

It depends on clearances

The M50 bridge is below standard for current clearances, so a mechanism is required to contain the train as to avoid striking the bridge

I cannot see what a check rail would do in those circumstances. Historically check rails were added once a rail track radius went below a certain measurement.

Captain Chaos

There is more less a check rail on everything south of Connolly station to the north end of Pearse to protect the loopline. Not a hope of a train ever derailing on that section as they are big thick check rails.

I always found the ones on the line out to Greystones odd as they are placed in the middle of the ties and not up beside the running rails. I'm sure they is a reason for it but I can't figure the advantage of placing them there compared to "normal" check rails.

BoatMad

Captain Chaos wrote: »

There is more less a check rail on everything south of Connolly station to the north end of Pearse to protect the loopline. Not a hope of a train ever derailing on that section as they are big thick check rails.
[

again sharp curves

I always found the ones on the line out to Greystones odd as they are placed in the middle of the ties and not up beside the running rails. I'm sure they is a reason for it but I can't figure the advantage of placing them there compared to "normal" check rails.

I think you may be looking at replacement rails, they are often dropped into the centre of the track

Jamie2k9

I think you may be looking at replacement rails, they are often dropped into the centre of the track

They are no, they are welded down as they are at Park West (M50) and BlackWater in Mallow to name a few.

BoatMad

Jamie2k9 wrote: »

They are no, they are welded down as they are at Park West (M50) and BlackWater in Mallow to name a few.

Pics ?

Maybe I'm showing my age, but for me check rails always looked like this.

Jamie2k9

BoatMad wrote: »

Pics ?

http://www.irishrail.ie/media/may_timetable_24042015.pdf?v=8rhurqe

BoatMad

Jamie2k9 wrote: »

They are no, they are welded down as they are at Park West (M50) and BlackWater in Mallow to name a few.

I am told , that these types of rails are installed to try and contain derailments as opposed to normal check rails ( where " trivial " derailments might lead to severe consequences, like along the bray head area for example )

101sean

I've just started ploughing my way through 450 pages of 'The Railway, British Track Since 1804', I'll let you know what it says on check rails in about 3 months time!

BonkeyDonker

101sean wrote: »

I've just started ploughing my way through 450 pages of 'The Railway, British Track Since 1804', I'll let you know what it says on check rails in about 3 months time!

get an electronic version and CTRL-F