British Rail Class 42: Encyclopedia II - British Rail Class 42 - Service

British Rail Class 42 - Service

The D800s were originally intended for the Paddington-Birmingham route and tests proved that their extra weight and power allowed them to run to a two hour schedule with 368 tons in tow: one coach more than a Class 40 could manage. These plans were put back when Paddington became the temporary London terminus of choice for Birmingham during the early 1960s, whilst BR's preferred route from Euston via Rugby was electrified. Loads of greater than 370 tons would be required and the service remained steam-hauled until the advent of the more powerful "Western" diesel-hydraulic locomotives. The first service route for the class therefore became Paddington-Penzance both via Bristol and the "Berks and Hants" route via Westbury. This allowed for elimination of steam on the difficult-to-operate railway west of Newton Abbot. In October 1958 D800 became the first locomotive to take up the class' new diagram of the up Cornish Riviera Express (Penzance to Paddington), the 18:30 Paddington-Britsol and the 21:05 Bristol-Plymouth - the last part of the diagram allowing the locomotive to return to the brand new depot at Laira in Plymouth once this was fully operational in 1961.

The maximum speed of the D800 class was officially 90mph but this could not be rigidly enforced because the transmissions could not be precisely governed. 102mph was recorded by D801 in private tests during 1959, albeit on a downgrade. The summer of 1959 saw 100mph service trains diagrammed for D800s with the Paddington-Bristol "Bristolian" set a schedule of 100 minutes. The outward journey was via Bath and required an average speed of 71mph and the return journey via Badminton averaged at 70.6mph. For a very brief period the D800s achieved both the schedule and more with D804 exceeding 100mph three times on one early run from Bristol. This was soon ended when the Western Region's civil engineers imposed a blanket 90mph maximum speed on all the Region's main lines, where for five years there had, uniquely to BR at the time, been no restrictions at all. The root cause of this worry was the effect of small-diameter powered wheels carrying far more weight per inch of tread than those of a steam locomotive. These concerns arose particularly from experiences in the United States of America although the significant rail damage reported there was mostly caused by wheel sliding under braking with heavy tailing loads which were very unlikely to occur on BR. With the benefit of modern hindsight it is possible that, even though the full US experience would not be replicated, "gauge corner cracking" (the formation of microscopic cracks in the rails that was the primary cause of the Hatfield rail crash of 17 October 2000 in the UK) could have been a possibility if the schedules had been adhered to.

In the event, several D800 drivers began reporting uncomfortable lurching over points or on poorly-maintained track at high speeds around this time. The problem was eventually traced to the novel design of the bogies and their means of attachment to the locomotive bodyshell: it had given the German V200s no trouble because of the system-wide 75mph speed limit on the German Federal Railway at the time. High speed running magnified the effect of the almost rigid link between body and bogie and oscillations created in the entire locomotive structure when the wheels hit pointwork or indifferent track made derailment a very real risk as the tyres on the wheels wore down. The D800s were subject to a maximum speed of 80mph until all class members could be modified - this was not achieved until 1963. The "Bristolian" was decelerated by 5 minutes but an extra stop at Chippenham was inserted so that the drivers practically had no choice but to exceed 80mph in order to keep to time. All speed running ceased after autumn 1960, when BR's timetabling methodology as a whole changed towards making all inter-city services more regular interval with standardised train formations and more intermediate stops. No longer would crack expresses such as the "Bristolian" be given such priority: the hope (largely successful) was to increase locomotive and coaching stock productivity and also increase passenger numbers in an attempt to curb BR's still-increasing monetary losses.

By 1964, the influx of both more powerful "Western" diesel-hydraulics and Class 47s drafted into the WR by BR's higher management, meant that some D800s were spared for use on the Waterloo-Exeter route. At this time, the Western Region (formed upon Nationalisation in 1948 largely from the Great Western Railway) had just assumed control of this line west of Salisbury from the Southern Region of British Railways and conveniently used the "no more crack expresses" edict to get revenge on its pre-Nationalisation rival the Southern Railway by withdrawing altogether the SR's "Atlantic Coast Express", which worked beyond Exeter, and replacing it with a semi-fast Waterloo-Exeter service hauled by D800s. The WR also took the opportunity to reduce its former rival's main line to single track for long stretches west of Salisbury and to sell off the "surplus" land - a move that is widely regretted today.

The late 1960s saw a brief revival in the fortunes of the D800s. By this stage they had been moved to duties such as Paddington-Birmingham (drastically reduced in importance since the 1966 opening of the electrified London Euston-Birmingham route, and re-routed to Birmingham New Street station following the closure of Birmingham Snow Hill), and Paddington-Hereford. Rising traffic levels on the Paddington-Plymouth axis meant the WR aspired to an hourly service interval for this route with standard 10 and 12 coach passenger rakes. The maximum schedule was to be 4 hours 15 minutes for the 225.5 miles, but the "Cornish Riviera Express" would be retimed for 3 hours 45 minutes with stops at Taunton and Exeter only. The Westerns could only cope with these timings on 7 coach sets. The answer was to assemble pairs of D800s and reinstate the multiple working equipment on them, to allow the pair to be controlled by one driver. This was done with D819/22/23/24/27/28/29/31/32 and D866-69 and the acceleration in schedules did bring a further 7% increase in traffic levels. It was not, however, without its problems: a fault on one locomotive in a multiple-unit pair effectively disabled both and one alone could not keep to the schedules. By 1969 only two services were booked for a pair of D800s, albeit losing a further 15 minutes off the schedule, and the timetable was largely recast into separate Torbay and Plymouth trains, instead of being split en-route. This allowed the formations to revert to 8 or 9 coaches that a single Western could handle alone.

Adapted from the Wikipedia article "Service", under the G.N U Free Docmentation License. Please also see http://en.wikipedia.org/wiki