High Speed Rail - Transport Committee Contents

Annex 2: Capacity calculations

Briefing note on capacity issues by Richard Goldson and Bob Linnard, Specialist Advisers to the Transport Committee, October 2011.

West Coast Mainline - Supply and Demand

1. A key reason cited by the Government for building HS2 is the extra passenger and track capacity it would provide. Some critics argue that upgrading the existing WCML would provide sufficient capacity for the foreseeable future. This note examines the supply of extra capacity under different options and the demand for capacity (the latter based on information provided by DfT and HS2 Ltd).[343]


2. The table below summarises the extra capacity that would be provided on WCML under three options - HS2 London-Birmingham, the conventional upgrade modelled by DfT (Rail Package 2 - RP2) and the variant to that proposed by 51m.[344] It also shows the percentage capacity increases relative to the HS2 reference case date (2008).

3. It shows that the recent upgrade and high-frequency timetable have already increased capacity from 90,000 seats per day in 2008 to 120,000 seats in 2011.

4. The RP2 and 51m proposals would both increase that 2011 figure by a further 80% to 90% to around 220,000 seats. Either could probably be implemented by 2016. Both these proposals would provide a rather smaller increase in the seats available in the peak - around 60% (relative to 2011) in the case of 51m.

5. HS2 would provide significantly more additional capacity than RP2 or 51m. It would increase the daily capacity (relative to 2011) by some 145% to nearly 300,000 seats, and the peak capacity by a similar percentage, albeit not until 2026.


6. HS2 Ltd has provided information on current and forecast long-distance (100 miles and more) trips on WCML, though only on the franchise currently operated by Virgin.[345] That proviso means that the figures for demand are not directly comparable with those above for supply. The important thing is the relative rate at which supply and demand increase.

7. In 2008 there were 50,000 long-distance trips per day over the southern end of Virgin West Coast. By 2011 this had risen to about 65,000. DfT's standard model for forecasting rail passenger demand shows growth of 2% per year, well below the 10% per year actual growth from 2008 to 2011 on WCML. This means that the forecast of 57,000 trips by 2021 has already been exceeded. Similarly, it means that the forecast of 101,000 trips by 2043 - about 50% more than today - is probably too low.

8. But if the model is right and demand quickly drops back to 2% per year, then RP2 or 51m would provide enough capacity for perhaps 20 years, at least on an all-day basis.

9. HS2 Ltd says that HS2 would of itself increase demand - by an extra 37%.

Load Factors

10. The load factor is the rail industry measure of crowding. A load factor of 100% means that all seats are occupied. (If the journey is less than 20 minutes it would also assume standing within the design limits of the rolling stock.)

11. DfT's figures show load factors on Virgin West Coast between London and the West Midlands (the busiest stretch) at 56% in 2008, dropping to 42% in 2021. That reduction reflects the extra capacity created by the recent upgrade running ahead of the 2% per year modelled demand growth. But as with the demand figures in paragraph 8 above, the 2021 forecast does not reflect the actual 2008-11 surge in demand.

12. By 2043, without HS2 or any alternative, the load factor is forecast to have risen to 76%. That reflects a forecast doubling of 2008 demand. But RP2 or 51m would broadly double today's supply of capacity. So why might we need the much bigger increase in capacity offered by HS2 (which, even allowing for the 37% increase in demand that the new line would generate, would by 2026 give a much lower average load factor than any alternative)? The answer lies in the way demand is concentrated at peak periods.

Peak Demand

13. DfT/HS2 Ltd acknowledge two limitations in their figures. First, as noted, they ignore the actual demand growth over the past 3 years. Second, the load factors are all day averages which will mask much higher demand in the morning and evening peaks. The question of whether these peaks can be spread is crucial.

14. The McNulty report on rail value for money urges a move from predict and provide to predict, manage and provide, i.e. using different pricing structures to make better use of capacity. DfT have largely dismissed the scope for this on WCML, arguing that 9-5 commuting is here to stay for the foreseeable future.[346] If they are right then even a (probably understated) 76% all-day average load factor would lead to unacceptable peak crowding, reinforcing the case for the step change in capacity provided by HS2.

15. As an aside, if DfT are right that demand cannot be spread and the 10% annual growth of the past three years were to continue, even pressing ahead with HS2 would mean severe overcrowding for commuters post-2020, given that HS2 cannot be in operation before 2026.


16. HS2 is needed for capacity reasons if the growth of the last 3 years continues or if peak demand cannot be spread.

17. If the growth rate were to fall back quickly to 2% per year (or less) RP2 or 51m would suffice, but only if an answer could be found to the problem of peak demand.

Table 1
Interventions  Daily Trains Daily Standard Class Seats

(Increase over 2008 Base)  

Daily Seats (Std + 1st)

( Increase over 2008 Base)  

Peak Standard Seats (one hour, one way)

( Increase over 2008 Base)  

Peak Seats Std + 1st (One hour, one way)

( Increase over 2008 Base)  

Train investment with no/little infrastructure investment         
HS2 2008 Base (Reference case)   59,298  90,000 2,289  3,482 Gross figure obtained from HS2 Strategic Alternatives Study. Peak hour figures estimated.  
Current timetable 286  81,924








Includes Voyager services (30 daily).  
Evergreen 3 (2011 Chilterns line upgrade)  [68] [28,900]




  Committed scheme, complete in 2011, but excluded by 51m and here as it is unclear how much of the capacity is actually available to WM passengers after allowing for intermediate usage to Bucks, Oxon and Warks.  
Committed train lengthening project  286 105,924








Committed scheme - implemented from 2012.  
December 2013 additional services  306 113,679








Additional hourly off-peak train each way. Note off-peak only.  
First class reconfiguration as proposed by 51m  306 134,379








One car converted from first to standard class.  
12 car sets as proposed by 51m (except Liverpool)  306 166,908








Major physical constraints at Liverpool.

Infrastructure investment, proposed by 51m to relieve pinchpoints         
30 additional services enabled  336 186,648








Total envisaged by 51m  336 186,648








Increase over Current  50 104,724








RP2    224,600


  Estimated from Strategic Alternatives Paper and calculations re Evergreen  
RP2 Increase over Current    104,366


HS2 (West Mids) Proposal

(All New Capacity)  

336   174,900

(194% over base)

(145% over current)  


(205% over base)

(154% over current)  

Assumes 15 hour day with 3 hour peaks; all trains 550 capacity, except 50% of Birminghams will be 1100  
HS2+Y Proposal (West Mids & NW only)

(All New Capacity)  

312   184,800   8,800 Assumes 15 hour day with 3 hour peaks; all trains 550 capacity, except 50% of Manchesters and Birminghams will be 1100  
HS2+Y Proposal (All destinations)

(All New Capacity)  

492   283,800   12,100 Assumes 15 hour day with 3 hour peaks; all trains 550 capacity, except 50% of Manchesters and Birminghams will be 1100  

343   Ev 267 Back

344   Ev 154 Back

345   Ev 267 Back

346   Ev 254 Back


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Prepared 8 November 2011