die belebende Bedenkung

HS2 speed and capacity loss

with 5 comments

On 23 February 2017 the HS2 London West Midlands bill gained royal assent after ‘3 years of Parliamentary scrutiny’.

But how effectual was the ‘scrutiny’?

And how competent are HS2’s senior officers – such as the chairman?

On 17 November 2014, HS2 Ltd’s David Higgins told the House of Commons transport committee that “a railway line where trains travel at 220 miles an hour as opposed to 120 miles an hour clearly has nearly twice the capacity because you can have twice as many trains on it. Once we started talking about capacity, then people started to get it.

Extract from David Higgins' comments about high speed rail capacity to the Commons transport committee, November 2014

David Higgins’ claim was utter nonsense. But no-one on the transport committee challenged him about it. And unlike the Beleben blog, the ‘technical’ railway press has never challenged or debunked the claim.

On 13 January 2015, Mr Higgins again paraded his technical illiteracy, this time before the House of Lords economic affairs committee.

Extract from David Higgins' comments about high speed rail capacity to the Lords economic affairs committee, January 2015

Someone at HS2 Ltd must have known that David Higgins was giving misleading and inaccurate information to Parliamentary committees. Because Bombardier’s 2011 high speed rail capacity report was written for the company.

'Figure 3: Headway as a function of block section length on level track', Bombardier Transportation capacity report for HS2 Ltd, 2011

‘Figure 3: Headway as a function of block section length on level track’, Bombardier Transportation capacity report for HS2 Ltd, 2011

According to Bombardier’s diagram, the capacity loss from running at 360 km/h compared to 200 km/h, could be thought of as (Z – Y), with 400 metre signalling blocks. Plainly, with other block lengths, capacity is also lower at 360 km/h than at 200 km/h.

With 400 km/h operation, the capacity loss is exacerbated further.

Written by beleben

February 28, 2017 at 12:15 pm

Posted in HS2

5 Responses

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  1. If you consider capacity as the number of trains simultaneously on the line at any given moment then any increase in speed will lower the capacity. If, on the other hand you consider the capacity to be the number of passengers that can be delivered from one end of HS2 to the other, then capacity will increase with speed until you reach a crossover point where signalling system capability, braking capability, and passenger comfort under braking, limit further increases. This assumes that passenger capacity of the train doesn’t change.

    John Beaulieu

    March 6, 2017 at 12:13 am

  2. […] 2016 letter supposedly written by HS2 then-chief executive Simon Kirby, aimed at explaining away misinformation given to parliamentary committees and a railway […]

  3. Dr Paul Thornton

    March 29, 2017 at 11:16 am

  4. […] Affairs team hold any correspondence between HS2 Ltd and DfT that references or relates to the statements made by David Higgins in relation to speed and capacity at parliamentary select select committees […]

  5. […] the blog HS2 speed and capacity loss, Beleben website, […]

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