[PR] Leaves on the line & low rail adhesion

[Colm Moore]

http://www.irishrail.ie/news_centre/news.asp?action=view&news_id=1218

Leaves on the line & low rail adhesion by Corporate Communications

“We apologise for the delay – this is due to slipping caused by leaves on the line.” It’s the announcement that causes eyes to roll, and heads to shake in disbelief.

But, come October, it’s a problem that this and every other railway has to face, and as the railway’s least favourite ‘season’ is underway, we thought it would be helpful for customers to explain how exactly ‘a few leaves’ can cause hundreds of tonnes of train to be delayed.

When leaves fall on to the line, particularly in damp or wet weather, the rolling action of passing wheels compresses them, causing a greasy ‘mulch’ to cover the rail.

This mulch is to rails what ice is to roads. It reduces the adhesion, or ‘co-efficient of friction’ to use the technical term, between wheel and rail. Acceleration must be reduced to prevent slipping, and braking distances extended. If you’re a regular customer, you can probably sense the wheel “slipping” on a train if you’re travelling through an area that’s affected. This is why minor delays are more prevalent at this time of year, particularly in the early morning and early evening.

The leaf mulch can also affect the operation of track circuits. Iarnród Éireann has machinery to address this problem, which operates overnight on key sections of the network, spreading “Sandite” on the line. However, this can only reduce the impact of leaf mulch rather than eliminate it. The mulch is Teflon-like, and even hand-scrubbing could not remove it. We’re not alone in this, as this article shows: http://en.wikipedia.org/wiki/Slippery_rail

The number of weeks this can continue for varies from year to year, depending on weather conditions. However, we will continue to work throughout the period affected to minimise delays on services, and apologise for the inconvenience caused.

[Mark Gleeson]

Usual excuses.

Over 50% of the network no longer relies on track circuits and proven technical solutions in in place to address that issue with track circuit assistance devices

Of course Irish Rail does not employ high pressure water cleaning so its like putting a plaster over a dirty wound.

[karlr42]

Originally Posted by Mark Gleeson

Over 50% of the network no longer relies on track circuits

True, but the parts that do, the DART line and Commuter lines to Maynooth and Drogheda, are the busiest lines in the country and most affected by delays due to the frequency and volume of passengers.

[Mark Gleeson]

Clontarf - Malahide/Howth go axle counter in a matter of weeks.

All non electric trains are fitted with proven devices to make the track circuits work in poor conditions. So failures are rare and could not explain the level of delay experienced on the ground

[Inniskeen]

The major issue with the leaf fall season is wheel slip on starting and wheel slide during braking rather than wrong side track circuit failure. Adhesion problems are componded by the demise of traditional clasp braking which when applied had the effect of cleaning the wheel surface.

While other railway operators also struggle with leafs, many deploy sand much more extensively than Irish Rail. Indeed in some countries it is a legal safety requirement for trains to have sanding equipment fitted and operational. Modern rolling stock often utilises sand as an integral part of the the traction and braking management systems. As I understand it such systems are typically disabled by Irish Rail.