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Route availability
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<h2 id="line-calculations">Line calculations</h2> <p>The route availability for a line is calculated by taking into account bridge strength, track condition, structural issues and so on. A route availability of one (RA1) is the most restricted line, open to possibly one type of locomotive specially designed for it. A route availability of 10 is the most open, usable by any locomotive that fits within the GB <a href="/facts/Loading_gauge/DWdNjFXB">loading gauge</a> that has been 'passed' for it (checked for conflicts with infrastructure such as platforms). </p> <h2 id="vehicle-calculations">Vehicle calculations</h2> <p>Route availability for a vehicle (<a href="/facts/Locomotive/C9YV7wrQ">locomotive</a> or <a href="/facts/Wagon/RUVs11Yb">wagon</a>) is generally based upon its <a href="/facts/Axle_load/Hgaw2aAv">axle loading</a>. That is, how much of the laden weight of the vehicle is distributed on each axle. The more weight on each axle, the higher the RA number, and the more restricted the vehicle is. For wagons it is normal to have different RAs when running empty and full. </p><p>The RA of a locomotive must not exceed the RA of the track except under strictly controlled circumstances.<a class="footnote-ref" id="fnref:1" href="#fn:1"><sup>1</sup></a> </p><p>Thus a locomotive with RA 1 is able to work on any line, although it will have a very light axle loading. An RA 10 locomotive could only run on RA 10 lines, placing severe restrictions on where it can be used. </p><p>If a vehicle has wheels that require significant balance weights, often found on steam locomotives, the dynamic loading resulting in what is termed the <a href="/facts/Hammer_blow/sGdbv41U">hammer blow</a> action may affect the RA of the vehicle. </p><p><a href="/facts/Network_Rail/B7RcLTwY">Network Rail</a> currently gives the allowed axle loadings as follows:<a class="footnote-ref" id="fnref:2" href="#fn:2"><sup>2</sup></a><a class="footnote-ref" id="fnref:3" href="#fn:3"><sup>3</sup></a> </p> Axle loading by Route Availability<table><tbody><tr><th>Route Availability</th><th>Axle Load</th></tr><tr><td>RA3</td><td>≤16.5 tonnes</td></tr><tr><td>RA5</td><td>≤19.0 tonnes</td></tr><tr><td>RA6</td><td>≤20.3 tonnes</td></tr><tr><td>RA8</td><td>≤22.8 tonnes</td></tr><tr><td>RA9</td><td>≤24.1 tonnes</td></tr><tr><td>RA10</td><td>≤25.4 tonnes</td></tr><tr><td><i>EU average</i></td><td>≈22.5 tonnes</td></tr></tbody></table> <h2 id="historical-notes">Historical notes</h2> <p>Before <a href="/facts/Nationalisation/cQcRubNU">nationalisation</a> the <a href="/facts/Big_Four_British_railway_companies/1Vy8sA5G">Big Four</a> railway companies had their own classification systems. </p><p><a href="/facts/Great_Western_Railway_Power_and_Weight_Classification/A2f9PIAA">GWR's system for classification</a> featured a coloured disc painted on the locomotive cab side to indicate its route availability: </p> GWR Route Availability<a class="footnote-ref" id="fnref:4" href="#fn:4"><sup>4</sup></a><table><tbody><tr><th>Disc colour</th><th>Axle load (long tons & cwt)</th><th>Axle load (lb)</th><th>Axle load (t)</th><th>Notes</th></tr><tr><td>(no disc)</td><td>up to 14 long tons 0 cwt</td><td>31,400 lb</td><td>14.2 t</td><td></td></tr><tr><td>Yellow disc</td><td>14 long tons 0 cwt up to 16 long tons 0 cwt</td><td>31,400–35,800 lb</td><td>14.2–16.2 t</td><td></td></tr><tr><td>Blue disc</td><td>over 16 long tons 0 cwt, up to 17 long tons 12 cwt</td><td>35,800–39,400 lb</td><td>16.2–17.9 t</td><td></td></tr><tr><td>Red disc</td><td>over 17 long tons 12 cwt</td><td>39,400 lb</td><td>17.9 t</td><td></td></tr><tr><td>Double red disc</td><td>22 long tons 10 cwt</td><td>50,400 lb</td><td>22.9 t</td><td><a href="/facts/GWR_6000_Class/mABluKqf">"King" class</a> only</td></tr></tbody></table> <h2 id="see-also">See also</h2> <ul><li><a href="/facts/Rail_speed_limits_in_the_United_States/3sqA4qdF">Rail speed limits in the United States#Track classes</a></li></ul> <ul><li>Ransome-Wallis, P. (1966). <i>The Last Steam Locomotives of British Railways</i>. Ian Allan Limited.</li></ul> <h2 id="external-links">External links</h2> <ul><li><a href="http://www.rgsonline.co.uk/docushare/dsweb/Get/Rail-30389/TT0138.PDF">British Railways Board Group Standard for Route Availability</a> (historical)</li> <li><a href="http://www.networkrail.co.uk/aspx/2230.aspx">Network Rail infrastructure capacity</a></li> <li><a href="http://www.2d53.co.uk/RA/RA1.htm">2D53 Introduction to Route Availability and tables</a></li> <li><a href="http://www.networkrail.co.uk/aspx/4996.aspx">Network Rail Information</a></li> <li><a href="http://www.rgsonline.co.uk/Pages/searchresults.aspx?Type=Adv&dStatus=2&dName=GERT8006">GE/RT8006 Assessment of Compatibility of Rail Vehicle Weights and Underline Bridges</a> (live issues) at RGS Online</li></ul> <h2 id="references">References</h2> <ol> <li id="fn:1"><p>Safety & Standards Directorate, Railtrack PLC (December 2000). "Interface between Rail Vehicle Weights and Underline Bridges - Appendix C - Flow chart of Procedure for Permitting a Train to Run" (PDF). Archived from the original (pdf) on 11 December 2007. Retrieved 17 August 2008. <a href="https://web.archive.org/web/20071211225925/http://www.rgsonline.co.uk/docushare/dsweb/Get/Rail-41549/GERT8006.pdf" target="_blank">https://web.archive.org/web/20071211225925/http://www.rgsonline.co.uk/docushare/dsweb/Get/Rail-41549/GERT8006.pdf</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li> <li id="fn:2"><p>Network Rail Loading Gauge documentation <a href="https://web.archive.org/web/20070812111543/http://www.networkrail.co.uk/aspx/2230.aspx" target="_blank">https://web.archive.org/web/20070812111543/http://www.networkrail.co.uk/aspx/2230.aspx</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li> <li id="fn:3"><p>Network Rail Route Availability <a href="http://www.networkrail.co.uk/aspx/10551.aspx" target="_blank">http://www.networkrail.co.uk/aspx/10551.aspx</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li> <li id="fn:4"><p>Ransome-Wallis (1966) p.181 <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li> </ol>