HS2 Questions

Examining the issues around the proposed High Speed 2 route

Are DfT’s new rail demand forecasts really ‘conservative’?

leave a comment »

DfT claim that their new forecasts (that still represent a doubling in demand) are for an annual rate of growth of less than 2% (1.4%), while over the past 15 years it has averaged 5%, hence they claim their forecasts are conservative.  However, DfT’s forecasts for the long distance routes at issue (WCML, MML and ECML) are all 2% or more.  The 1.4% is misleading as its not really for long distance journeys[1]. The reduction (from 3.4% in their March 2010 business case) is the result of using the latest [2]economic growth forecasts and the impact of three years of pricing at RPI+3%. 

In fact DfT’s forecasts remain excessive because:

  • To obtain a doubling in demand, they project demand growth for an unreasonably long period (35 years to 2043, 10 years longer than before) – despite their model being most suited to short term forecasting[3]
  • DfT use an out of date version of the forecasting model[4] that is now known to systematically overestimate growth in the longer rail journeys which are crucial to the demand needed for HS2 – and recent research for DfT confirms this
  • DfT also expect a major uplift in demand (on top of the doubling in background growth) as a result of the journey time reductions – but mobile technology is already making time on-board trains useful, so the uplift would be much smaller.

Overall domestic travel shows signs of saturation, for both total and long distance journeys[5].  Within this, rail’s share has increased since privatisation from the improved services, increased subsidy, and airline style pricing.  While rail’s share has not stopped growing yet, DfT accept it is unreasonable to project past trends forward indefinitely.

The effect of these erroneous assumptions can be calculated. Forecasting ‘background’ growth for only 25 years (2008 to 2033), as was done for the 2010 White Paper, and adopting the approach to demand income elasticities of the latest version of the forecasting model, at least halves the net benefit ratio (NBR) of HS2.  Economic and social benefits do not cover, or barely cover, the subsidy ie costs:

  • Phase 1: NBR drops to 0.6 (from 1.8), and with wider economic impacts to 1.0 (from 2.0)
  • Full ‘Y’ network: NBR is 1.0 (from 2.2), and with wider economic impacts 1.2 (from 2.6)

A reduction in the demand uplift with the introduction of HS2 would further diminish the NBRs.

Demand forecasts for rail schemes are notoriously overestimated.  More than 9 out of 10 rail projects have demand overestimated, on average by a factor of two[6].


[1]  1.4%/a is for all ‘strategic trips’ in their model and does not conform to normal over 50 mile definition of long distance (FOI 3 February 2011)

[2]  June 2010 economic growth forecasts by Office of Budget Responsibility

[3] DfT rail model (Passenger Demand Forecasting Handbook, PDFH) is a fixed elasticity model that over long periods predicts unbelievable increases in the proportion of income spent on long distance rail

[4] DfT use PDFHV4.1 not the latest Aug 2009 version 5.0. V4.1 income elasticity includes a ‘distance term’ that DfT sponsored research by Arup & Oxera says no longer applies. V5.0 has no distance term

[5] Section 1.1 of the ‘Review of the Business Case for HS2’, HS2AA, Feb 2011

[6] ‘Inaccuracies in Traffic Forecasting’ B Flyvbjerg, M Skamris Holm and S Buhl. Transport Reviews, January 2006.


Written by hs2questions

March 31, 2011 at 10:09 am

Posted in Uncategorized

Tagged with , ,

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )


Connecting to %s

%d bloggers like this: