Understanding Leaf Chemistry and Effects on Low Adhesion

点击翻译按钮获取中文摘要

Project summary:The rail network in the UK is responsible for 4 million journeys daily (1), with this number predicted to double over the next 25 years. As the global drive for more sustainable and environmentally friendly travel continues, rail companies and operators are being put under more pressure to improve safety and reliability, as well as encourage commuters to switch to rail for their commute. Leaves create a problematic "Teflon like" coating which adheres to the railhead while severely reducing friction to the wheels which roll/slide over it (2).Low adhesion in the wheel-rail interface can and does cause problems for braking and traction and significantly affects network performance in the Autumn period. The annual cost estimation of low adhesion to the whole of GB rail industry has been estimated to be in excess of £100 million (3). This cost is attributed to; refunds/compensation due to delays, incident investigation, maintenance repairs (wheelset re-profiling, replacing broken track), trackside vegetation management and more.The main aim of the project is to widen the understanding of low adhesion caused by leaves to include effects of different leaf chemistries, times that particular leaves fall and related weather conditions. This data will then be used with other fundamental knowledge of low adhesion (from RSSB projects on oxides and small amounts of water) to develop an improved adhesion index prediction. This improved adhesion prediction could reduce incidents and delays in the autumn period as well as improve reliability and appeal rail as a more environmentally friendly means of mass transportation.This work will expand the scope of the project currently under way by examining more leaves and bringing in the field side, i.e., friction assessment, effects of weather, information on leaf fall and entrainment of leaves and finally by helping to develop the prediction of adhesion problems.The aims proposed for this project include;Identify the main types of leaves present on UK rail track that cause low adhesion problems:Research current literature regarding leaf contamination in the wheel-rail interface.Investigate industry reports on railhead contamination, what are the more and less troublesome leaf species?.Research most common types of trees in the UK (deciduous only).To find operational data on the leaf problems and Key Performance Indicators (KPIs).Collect data about autumn weather conditions and leaf fall.Collect friction data throughout the autumn period to correlate with weather data.To investigate the chemical analysis techniques regarding leaves:Research the advantages and disadvantages of different chemical analysis techniques.Research the chemical analysis used in the literature.Find the ideal sample state for analysis techniques.Prepare the leaves for testing:Collect leaves and store safely until required.Prepare samples using the same method found in the literature.Carry out chemical analysis of the selected leaves:Contact relevant members of staff for training on required machines such as; FT-IR (Fourier Transform-Infrared Spectroscopy), XPS (X-ray Photoelectron Spectroscopy) and LRS (Laser Raman Spectroscopy).Carry out chemical analysis and collect data.Carry out tribological tests of the different leaves and leaf layers:Become trained on required rigs/machinery such as; SUROS (Sheffield University ROlling Sliding) rig, UMT (Universal Machine Tribometer), FSR (Full-Scale Rig) and Pendulum rig.Carry out tribological tests comparable to those in the literature.References;1.Passengers - Network Rail. [online]. [Accessed 12 February 2018]. Available from: https://www.networkrail.co.uk/communities/passengers/2.FULFORD, C. F. Review of low adhesion research. 2004.3.AWG, RSSB. Adhesion Manual Edition 6.0 [online]. 2018. [Accessed 29 May 2018]. Available from: https://www.rssb.co.uk/rgs/oodocs/rdg-awg ma