Route Alignments

A Comparison of Option E and CBRR Part 1 : Length and Capital Cost

Cambridge North Station

In this post we discuss just two of the parameters for a comparison: route length and capital cost. We conclude that the CBRR route is shorter and arguably has a lower capital cost than Option E. We end with some more questions for EWR Co.

This is actually good news. There is potentially a better option available for Cambridge, we just need EWR Co. to look at it again.

The references below set out some of the discussion so far on this topic.

The exact route alignment in the Option E area is still fluid at the moment and in order to make a comparison with the CBRR route, we need to make some assumptions:

  1. There is a station to the north of Cambourne near the junction with the A428, this has widespread support in the area and should facilitate the development of Cambourne, EWR Co. say they are looking at this.
  2. The option E route tries to maximise re-use of existing track and hence joins the Cambridge (or King’s Cross) line just south of Harston.
  3. The EWR Eastern Section connects to Cambridge via the single-track line to Newmarket at Coldhams Common

The routes are shown diagrammatically in figure 1

Figure 1 Diagram of CBRR and Southern Option E Route. Overall distances are measured from point A to point B.

Drawing out both these routes on a detailed map has allowed us to measure the distances shown in Figure 1.

CBRR Route is Shorter than Option E

Figure 2 Track Lengths between points A and B in Figure 1

We can see from the total distances in Figure 2 that the CBRR route is shorter than option E overall by 2.3km. This means that the transit time through Cambridge from west to east (or vice versa will likely be less than for option E. 

CBRR reached a similar conclusion comparing the 24km from Cambourne South to Cambridge South with the 23 km from Cambourne North to Cambridge North.

EWR Co. state that improved journey times are an important consideration. CBRR is better than option E in that respect.

Is CBRR Actually Cheaper than Option E?

Capital Costs £BnTechnical Report 2010 PricesOption Report 2010 Prices2019 Prices
CBRR 4.5
Route B2.23.43.9
Route E2.83.2?5.0
Table 1 Capital Cost Comparisons
Figure 3 Option B and CBRR taken from the Option Report

As pointed out in our earlier post about unexplained cost increases, route B had a much lower capital cost than route E at the time of the consultation, but the situation changed in the option report without much explanation. EWR Co. have so far declined to answer our questions about this huge change. 

Route B approaches Bedford from the north while Route E goes through a Bedford South station (Wixams). Their approach to Cambridge is the same. It seems sometime between the consultation and the option E decision, EWR Co. decided that approaching Bedford from the north was cheaper than from the south. We cannot accept this change without further explanation.

EWR Co. claim that CBRR is £0.6Bn more expensive than option B in 2019 prices. 

CBRR point out that if you take the cost ratios in the 2019 Technical Report we see that Route E’s capex is 27% (2.8/2.2) higher than Route B. Applying this 27% increase to the £3.9Bn given for option B would lead to an option E capex of £5.0Bn.  See Table 1 for the numbers.

It seems that option E is more expensive than CBRR using EWR Co.’s own figures given at the time of the consultation. As pointed out before, the mystery is why the ratio of Option B and E capex costs changed so much in the option report.

EWR Co. go on the say that comparing CBRR with option B is similar to comparing it with option E (option Report §16.30) There is a £200m capex difference even with their own figures in the Option Report and £600m capex difference in the Technical Report. Not small differences.

As previously noted, Route B and Route E are different at the Bedford end of the link. To compare apples with apples we really need to see what is happening between Cambourne and Cambridge. As EWRCo. have indicated, we can do this by comparing CBRR with option B, since they are the same at the Bedford end.

Cambourne to Cambridge Costs

EWR Co.’s Option Report states in $16.29 that the CBRR route will cost £600M more than some unspecified option B route in 2019 prices

Where could this £600M come from?

Figure 2 indicates that there is 3.3km of additional new track with the CBRR route compared with our assumed Option B/E route. 

If we take the approximately 50km route from Bedford to Cambridge and divide that into the £3.4Bn estimated capital cost for option B we find a cost of £ 68 Million /km in 2010 prices – this of course includes stations, road and river crossings etc.  It’s surprising that 3.3km of track could cost anything like £600M. Even £68M/km x 3.3km = £224.4M. That’s around £259.5M in 2019 prices.

These prices are all very high. In order to reduce noise CBRR proposed that the line be put in a sunken concrete trench. Have EWR Co. made allowance for that in their costings? If so it needs to be there for option E as well. We need an apples for apples comparison.

Part of this may be due to EWR Co. using a Cambourne South station for Option B/E rather than the Cambourne North one assumed here. However, as stated earlier, there is now a consensus that Cambourne North Station is the way to go. If so this analysis needs to be updated by EWR Co.

European Commission Report is the Taxpayer getting Value for Money?

While the Capex/km figures from EWR Co. do seem to be consistent with the much criticised HS2 costings, it is interesting to compare then with a survey of build costs around Europe published by the European Commission in 2017. In Figure 4 of this report we find that their model derived from actual builds gives a construction cost of 7.2MEuros/km for conventional track. Why are the costs here around 10 times as much? Is the taxpayer getting value for money?

The Imaginary Rowing Lake

In section §16.30 of their Option Report EWR Co. make allowance for the railway crossing a new rowing lake north of Cambridge. 

However, this rowing lake plan was abandoned and is therefore not an obstacle for the EWR link north of Cambridge. As a matter of fact, given that the news article is dated from the middle of 2018 and the EWR Co. option report is dated January 2020, this allowance was already out of date at the time that the option report was published.

Northstowe Station

The CBRR route has an additional station at Northstowe. This will form part of the additional cost for the CBRR route.  We know that the four tracked Cambridge South Station was estimated by Network Rail to cost £200m, but looking at this news article it seems reasonable to assume that a much simpler station at Northstowe should not cost more than £100m. A simple station at Harston was recently estimated to cost £20m, maybe that is a more appropriate figure.

Furthermore, as EWR Co. have said, they have not included any land value increase benefits around stations, (Option Report §15.16) which means that much of the potential benefit of Northstowe station is not included in the assessment. Such benefits can be very significant. The NIC report p.68 talks about a Milton Keynes case study with a tax of £18,500 per home for a new development. That would be £185M for the 10,000 homes mentioned in §16 of the Option Report. According to the same NIC report land values in the Cambridge area are twice what they are in Milton Keynes so this £185M is an under-estimate. 

The response to a recent FOI request to EWR Co. about land value increases, stated that they cannot share such information as it is commercially confidential. How can the public assess the value of various routes if even estimates of such information are kept confidential? In particular, as CBRR have pointed out and EWR Co. agree the land value increases for a northern approach to Cambridge will be higher than for the South. The difference is in the amount.

Are Upgrades to Existing Track Included?

Although they all only have two tracks at the moment, due to the high demand for commuter trains to London, the tracks south of Cambridge are much busier than those similar ones to the north. This is indicated in Figure 1 by the thicker lines on tracks south of Cambridge.

Looking at for the weekday busy hour timetable from Cambridge to King’s Cross we find 6 trains per hour (tph). We understand from EWR Co. that they want to start with a 4 tph service into Cambridge and to increase it to 6 tph if there is demand. As we have seen there is also a need to run freight trains, but we do not expect these to run during the passenger busy hour and so perhaps they will not affect capacity calculations.

It seems that the traffic into Cambridge from the south with the addition of the EWR link will likely double in terms of trains per hour. This will trigger the need to move from two tracks to four tracks certainly on the line from Gt. Shelford into Cambridge (according to EWR Co.) where there is also the traffic to Liverpool Street and maybe from Harston to Great Shelford as well. There may also be a need to replace level crossings e.g. in Great Shelford with some kind of road bridge.

The proposed upgrades around the Cambridge South station do not cover 4 tracking of much of the line.

So, the cost impact of the option B/E solution should include these improvements to the existing lines. Even if they are paid for by Network Rail rather than EWR Co. both are ultimately funded by the same taxpayers.


The CBRR route will be shorter than Option E. 

The CBRR route may well have a lower capex than Option E, especially when the full impact is considered.

The EWR Co. assessment of the CBRR route has some mistakes and several unanswered questions.

Question for EWR Co.

  1. Please can you acknowledge that a northern approach to Cambridge should lead to a shorter route to Cambridge from Cambourne North than a southern route?
  2. Do the costings for option E include any allowance for capacity upgrades to existing track required due to the additional EWR link traffic? If not why not?
  3. Do you agree that lines into the north of Cambridge are less busy than those into the south?
  4. Why did option B capex become higher than option E in the Option Report when this was far from the case in the technical report?
  5. What allowance was made for the rowing lake in the capital cost estimate for the CBRR route given in §16.30? Will you re-issue the comparison with this corrected?
  6. Please can you explain where the additional £600M for CBRR over Option B comes from?
  7. What assumption are you making for the cost of new track for capex/km?
  8. Why are the implied capital costs ten times as much as reported by this European Commission Report in Figure 4?

4 replies on “A Comparison of Option E and CBRR Part 1 : Length and Capital Cost”

Have you seen Anthony Browne’s Facebook post from earlier today publishing his correspondence from EWR in October/November?

My reading:

– Southern approach is done and dusted. It’s signficantly cheaper and there are severe technical challenges (eg reversing through Cambridge to continue eastwards).
– Diesel is likely.
– Freight is likely.


Excellent work Cambridge Approaches. This certainly makes you question how EWR have the come to their conclusions.
I had a reply from my email to Anthony Browne MP supporting a case for a station north of Cambourne and hope this is fully evaluated in future EWR analysis.

Thank you Cambridge Approaches, for such a thorough analysis of the comparative costs. EWR should not be allowed to tell us that it is cheaper to come South without clearly explaining every detail of their finding, and disproving the challenges that you have made. This is taxpayers money they are using, they must be held to account.

Please see the letter to Anthony Browne from the EWR Chief. They are sticking to the Option E as it “benefits the residents between Bedford and Cambridge” and Is the cheapest option as far as they are concerned.

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