Leaves On The Line
It's that time of year again. Everyone has heard the apologies for delays due to "leaves on the line" - but what does that mean? How can a small thing like leaves affect a big heavy train.
How leaves on the line affect train services
The leaf fall in autumn often causes poor rail head conditions and can affect train performance and punctuality in a number of ways.
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 between wheel and rail - hence the phrase "low rail adhesion". The leaf mulch can also affect the operation of track circuits.
Therefore, 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.
See how BBC's Bang Goes The Theory demonstrated the effect.
How we tackle low rail adhesion
We constantly work to reduce the impact of low rail adhesion through a range of measures:
- Vegetation management: Removing trees from our property, and making sure other vegetation is cut back and managed. Unfortunately, we can't remove trees from bordering properties.
- Sandite machine: We have machinery to address this problem, which operates overnight on key sections of the network, water-jetting and spreading “Sandite” on the line to improve the grip between wheel and rail.
- Traction Gel Applicators: Iarnród Éireann has also invested in Traction Gel Applicators – 110 of these units are installed across the network in known areas of low rail adhesion. When a train passes over the unit, it dispenses traction gel which improves the grip between the wheel and rail interface.
- Manual application: Hand held applicators and rail-head scrubbers are also stored in strategic locations to allow line maintenance staff provide a rapid response to other areas of slipping.
- On-board sanding: Iarnród Éireann has also equipped its passenger trains with on board sanding systems which will dispense sand when wheel slip is detected.
Michael Danaher our Infrastructure Manager in the East Region tells us more:
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.
For daily updates on service impacts from LRA and for the latest service information and news from Iarnród Éireann, follow us on Twitter.
Check out our Autumn Leafometer for how many leaves are left on the trees which we will keep updated throughout the season;