MANY railways suffer from slippery rails in the autumn, and Netherlands Railways is no exception. During a storm over the weekend of October 27-28 2002 NS was hit exceptionally badly, and rolling stock availability fell in the following weeks as many wheelsets had been damaged. A predictable public outcry ensued, and NS Reizigers decided that this should never happen again. An ambitious programme was therefore launched to prepare for the leaf-fall problems in autumn 2003.

Several actions were instigated by NS Reizigers and infrastructure manager ProRail with the immediate target of a significant improvement in autumn 2003. Preventive actions included improvement and replacement of wheelslide prevention systems, the application of Sandite to the rail head, the setting up of a low adhesion warning system, and the fitting of sanders to EMUs. A sixth underfloor wheel lathe was installed at Onnen, and a broad communications programme was set up to ensure that the public was kept informed.

AEA Technology Rail helped NS in several ways, in particular with the on-board sanding equipment and with the low adhesion warning system. The SmartSander (below left) is an automatic variable-dose sanding device that applies small amounts of sand to the rail head when the train slips during acceleration or slides when braking. Numerous EMUs have been fitted with the SmartSander in the UK, but in the Netherlands sanders have never been used on EMUs on a large scale before.

Based on the positive UK experience, NS decided to trial the SmartSander, and the challenge was to have the equipment accepted at short notice by both the national railway safety board and ProRail. Among tests carried out were measurements to demonstrate that pointwork is not harmed by the sand, that track circuits are not affected, and that braking distances are reduced on slippery track.

By October 2003 a nationwide low adhesion warning system known as GWS had been put in place. This automatically sends a warning of low adhesion conditions to the drivers of precisely those trains that may be affected. The system is based on 15 service trains that are equipped with the AEA Technology’s Low Adhesion Warning System¨. This logs events of traction slip and brake slide and relays this data to the IChex¨-based Low Adhesion Centre, using GSM and GPS technology. From there the location of the adhesion occurrences is sent by SMS to the trains that are to pass that location within the next 2 h. All this happens within 15min of the low adhesion conditions being detected.

Independent research centre TNO has evaluated GWS as highly effective, and initial reactions from train drivers were highly positive in that they can now adjust their driving technique to suit the adhesion conditions.

AEA Technology Rail was turnkey contractor for both projects. The SmartSander and GWS programmes were completed in four months from initial design to full acceptance and operational systems - in time for the low-adhesion season in early October 2003. NS Reizigers reports that although there were problems in autumn 2003, the low-adhesion conditions were managed more effectively than in previous years, with significantly fewer cancellations. n