Analysis and Case Study of Polymer Coatings as an Alternative to Galvanized and Bituminous Coated Steel Liner Plate Supports in Railroad Tunnels and other Railroad Crossing Tunnels

摘要

Steel liner plates have been an essential component of initial underground support systems since the mid-19th century. In many modern railroad applications, steel liner plates have been galvanized for corrosion protection and oftentimes bituminous coated for an additional measure of protection. It is generally accepted that a galvanized and bituminous coated liner plate placed in nominal underground conditions has a service life of about 75 years. Steady advances in molecular chemistry and development of long chained polyamides have brought forth the potential use of polymer coated liner plates in railroad tunnels and other railroad crossing tunnels. The use of galvanized and bituminous coated liner plates utilizes both products and processes that are difficult to manage in an era of increased environmental oversight and corporate environmental conscience. Utilization of galvanized and bituminous coated liner plates also presents unnecessary effort during construction as they are heavier and more difficult to handle while mining is taking place. Additionally, storage of the coated plates prior to installation is further complicated in hot and cold environments with bitumen flowing or cracking during storage. Lastly, shipping costs are escalated by increased weight. Conversely, polymer coated liner plates consume fewer raw materials and provide comparable durability while lowering installation costs due to improved handling and lower component weight. Additionally, hardware, namely nuts and bolts, can be polymer coated, if necessary for extended and uniform use. This paper will review the coating processes and environmental costs in production of both products and compare the advantages and disadvantages of each. Polymer coated liner plates are a value added substitute for galvanized and bituminous coated liner plates that provide an equal service life for less financial cost and a reduced environmental impact.