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The unbearable lightness of beam

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Network Rail’s multi-billion pound modernisation of the Great Western route includes extension of 25kV ac overhead electrification from Greater London to Newbury, Oxford, and South Wales, using Furrer+Frey‘s new “Series 1” kit.

 Series 1 and Mk3 overhead comparison, for individual lines

Network Rail 21st century Series 1 and British Rail 1970s Mk3 overhead line comparison

Series 1 is (supposedly) quicker to install than previous designs, but the programme is running around two years late, and massively over budget. Network Rail is now prioritising completion of a section between Reading and Didcot – encompassing the Goring Gap, and two areas of outstanding natural beauty – for testing Hitachi IEP trains.

But the “huge metal goalposts” intended for installation on multi-track sections have been criticised for their visual impact. Some Goring Gap residents have proposed the use of Mk3-style headspan, instead of the goalposts, but Network Rail have refused to consider the idea.

 Goring Gap 'ugly scar' railway gantries removal call , BBC News, 20 October 2015

BBC News, 20 October 2015

What isn’t clear, is why Network Rail are using huge castellated and Vierendeel-type beams, instead of less intrusive designs. At present, aesthetics do not seem to figure very highly in the company’s way of thinking.

Woodhead with Liverpool - Hull express geograph-2842190-by-Ben-Brooksbank (Creative Commons Attribution Share-alike license 2.0)

Steam train under the Woodhead 1500 V dc multi-track electrification, 1953 (Ben Brooksbank)

Even the 1940s / 1950s LNER Woodhead portals – designed for heavier 1500 V dc cabling – seem to have a lower visual impact than those newly-installed in Oxfordshire.

Woodhead route in the 1950s, electric intercity train

Woodhead route, electric intercity train

Network Rail environmental statement cover featuring a lattice-type gantry (which is not being used on the Great Western electrification)

Network Rail environmental statement, featuring a lattice-type gantry (which is not being used on the Great Western electrification)

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Written by beleben

November 3, 2015 at 11:37 am

Posted in Railways

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  1. The “Why Series 1” photo shows single track supports, not a gantry or headspan such as would be used where there are more than two tracks. I can understand that headspans may be problematical but their visual footprint is minimal compared to any of the other offerings shown. It is hard to believe that the Series 1 is the best way of eliminating the “nearly 100 known faults” with the Mk3 and that it will not introduce some of its own.

    Surely 65 years of technical progress in steel should be able to reduce the amount of steel needed. Perhaps the Woodhead electrification gantries were made with Sheffield steel and the GWR ones use cheap Chinese steel. The GWR gantries remind me of the ghastly UK motorway gantries which seem to be equally over-the-top compared with the much lighter ones used throughout Europe.

    The GWR OHLE only has to power Hitachi’s 260m (max) IEP (Incredibly Expensive Procurement) trains capable of 125-140mph. Wikipedia suggests the IEP has a traction power of 4 Megawatts but that sounds rather low as the quoted power of a similar length Pendolino is 6 Megawatts. What sort of gantries will be required for HS2 where a 400m train will need well over 24 Megawatts to run at speeds up to 250mph? With 18 trains proposed each way in an hour how big will the OHLE cables and supports need to be?

    johnma

    November 4, 2015 at 7:09 pm


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