Leaves On The Railway 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, which is a key element of train signalling. The contamination is very difficult to remove from both wheels and rails and is often compared to Teflon, being very difficult to remove and very slippery.

In order to comply with safety requirements Train Drivers adopt defensive driving techniques. This includes reducing speed to prevent slipping or over running platforms or signals, and as braking can be affected, braking distances are extended.

If you’re a regular rail traveller, you can probably sense the wheel “slipping” on a train if you’re travelling through an affected area. This is usually why 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

Iarnród Éireann have adopted proactive and reactionary measures to reduce the adverse impact LRA can have on Safety and Performance:

• 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, and we are constrained by environmental controls such as avoiding bird nesting periods
• Specialised water-jetting and gel application machine: We have a train which has specialised machinery to tackle railhead contamination. The train operates prior to early morning services on key sections of the network. It tackles the problem by cleaning the railhead with a high powered water jet at the front of the train and then applying a special ‘gel’ substance to the rail. The specially formulated gel consists of material that improves adhesion between train wheels and the railhead
• Traction gel applicators: Iarnród Éireann has also invested in Traction Gel Applicators – 116 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 gel application: Hand held gel applicators, and specialised rail-head scrubbers are positioned at strategic locations, near junctions etc. and are utilised by specially trained maintenance staff in order to provide a rapid response when necessary
• Regular train on-board sanding equipment: Most of our rolling stock has been equipped with on board sanding systems which will dispense sand when wheel slip is detected. During 2016, sanding systems were installed on 2600 railcar sets. During 2017, sanding systems were installed on locomotives which will assist traction effort on MKIV Cork services and De Dietrich Belfast services.
• Best practice: Low rail adhesion affects many countries with a temperate climate and Iarnród Éireann are a member of a group consisting of UK Train Operating Companies, which meet on a regular basis to tackle the problem
• Data Collection: We have a dedicated team of people which continuously work on ways of tackling the various components that come together and cause the problems described above. Low rail adhesion has been causing difficulties for many years. Continuous monitoring has allowed us build up a valuable database. This allows us focus on specific low rail adhesion contributory elements, such as known hotspots which we target specially
• Frontline Staff: Tackling low rail adhesion can be a difficult task. Iarnród Éireann staff work tirelessly to ensure our rail system operates safely in these conditions. This often involves frontline staff members from each of different departments working at all hours in all weather conditions. The dedication of these people means that the difficulties experienced at this time of year are kept to a minimum
  

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 low rail adhesion 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;