Changes

The cab side On 1 July 1905 the GWR introduced a system for denoting the haulage capabilities and weight restrictions applicable to the various classes of GWR their locomotives. From mid-1919 this information began to be displayed on the locomotives from themselves, enabling railway staff to make a quick assessment of a locomotive's capabilities without the need to refer to tables of data. The display took the 1920s onwards carried form of a coloured disc bearing a letter. The colour of the disc showed the locomotive’s locomotive's axle weight classification, which determined which routes the locomotive could work on. The letter showed the locomotive’s locomotive's power classification, which was used to determine the maximum load it could haul on each route. The disks were initially placed high on the cab side but were moved to a position just above the cab number plate during the Second World War to make them easier to see during blackout conditions.<ref>Wikipedia</ref>

GWR locomotives currently or formerly resident on the SVR were classed as follows:{| class="wikitablesortable mw-collapsible"

|[[GWR 1450|1450]]||1400 class||Unclassified||1P|| Unclassified

|[[GWR Pannier 5786|5786]]||5700 class||C||4F by BR(W)||Blue (Yellow from 1950)|-|[[GWR 5600 class 6634|6634]]||5600 class|| D ||5MT ||Red |-|[[GWR 6960 Raveningham Hall|6960]]||6959 Modified Hall class||D||5MT||Red

Certain routes could be modified as “dotted”"dotted", for example "Dotted Blue" meant a route could be worked by "Blue" locomotives but subject to a 25mph speed restriction. Locomotives in the lower "Yellow" and "Uncoloured" classes could work the route without this additional speed restriction.  The axle weight was the main factor used in determining route colour, but this could be varied where it was considered appropriate. An example of this was the 5700 class pannier tanks, which were reclassified from "Blue" to "Yellow" by BR(W) in 1950. The reason given was the low 'hammer blow' that the class produced, which reduced the wear on the track.

During the Second World War, in order to meet wartime requirements, the line was raised from a yellow to a blue route (although restricted to engines with a maximum axle loading of 17&frac12; tons), before eventually becoming a dotted blue route.<ref>[[Bibliography#Books|Smith (1968)]] pp. 24-25.</ref><ref group="note">Marshall refers to the line as 'dotted blue' without stating that it was a 'yellow' route pre-War, however the absence of evidence of blue rated locomotives prior to that time suggests this was the case.</ref> The post-War classification and rules for working the Severn Valley Railway were set out in Section 15 of the 1948 Working Timetable as follows:

After nationalisation, BR adopted During the Second World War the LNER developed a somewhat more refined sophisticated version of the GWR's route availability classification systemwhich was adopted by BR after nationalisation. Route Availability was based on classes RA 1 to RA 10, while and took into account the weight per foot length of a locomotive rather than just the simple axle loading used by the GWR. BR also adopted the LMS classification system for locomotive power was based on classes 0 to 9 with distinctions made for Passenger, Freight and Mixed Traffic. <ref>[https://www.devboats.co.uk/gwdrawings/weightrestrictions.php devboats.co.uk]</ref><ref>Wikipedia</ref> However in BR's Western Region, the old GWR system continued to be used on ex-in use until after the Severn Valley Branch closed in 1963, with BR locomotive classes being allocated the relevant GWR locomotives on route colours. For example a BR Standard Class 4 tank engine such as [[80079]] was given the general BR Western Regionclassification of axle load class RA5 and power class 4MT. Within BR(W) the route availability became "''Class 4 (2-6-4T) (80XXX): Prohibited on 'Yellow' and 'Uncoloured' routes. Restrictions – as for 'Blue' engines.''"<ref>Wikipedia[http://www.michaelclemensrailways.co.uk/?atk=559 ''British Railways Western Region, Locomotive Route Availability, June 1963'' via Michael Clemens]</ref>. One result of BR's new method of assessing weight restrictions without solely relying on axle weight was that the 5700 class pannier tanks were reclassified from "Blue" to "Yellow" by BR(W) in 1950. The reason given was the low 'hammer blow' that the class produced, which reduced the wear on the track.

When the SVR began operations in 1970, the line was still subject to the 17 tons 12 cwt axle weight restriction. This meant that large locomotives such as [[61994 The Great Marquess]] could not be used until a program of upgrading the line had been undertaken. The successful completion of this means that the SVR has since hosted a GWR 'King' class locomotive, as well as similar classes of locomotives from other companies. However sections of the line such as [[Victoria Bridge]] remains remain subject to operating procedures which restrict the double-heading of locomotives. The Light Railway Order under which the SVR operates specifies a maximum speed of 25mph for normal services. [[High speed testing|Operation up to 50mph]] may be carried out between Kidderminster and Bewdley when the railway is closed to the public; a recent example being the testing of Metropolitan Railway 0-4-4T No 1 in 2012 prior to its participating in the London Underground events in 2013. ==Notes==<references group="note"/>

The Light Railway Order under which ==See also==*[[Steam Locomotives]]*[[Locomotives used on the SVR operates specifies a maximum speed of 25mph for normal services. Operation up to 50mph may be carried out between Kidderminster and Bewdley when the railway is closed to the public; a recent example being the testing of Metropolitan Severn Valley Branch in commercial service]]*[[Great Western Railway 0-4-4T No 1 in 2012 prior to its participating in the London Underground events in 2013.]]