EWR Co’s Appendix F to the Technical Report contains two tables comparing the northern approach into Cambridge with the southern approach using a variety of parameters. They include such factors as length of viaducts, impact on residential areas, number of bridges required and impacts on environmental sites such as SSSIs and scheduled monuments. Cambridge Approaches has carried out a similar exercise months before East West Rail and presented the conclusions to the press, to EWR and to the rail minister. The tables from EWR Co are in response to our work. Now that we have confirmation of the route and the results of EWR Co analysis we have updated our assessment as shown in this post to show what we believe is a fairer comparison between the routes.
EWR Co presented their comparison tables to local councillors on the opening day of the of the consultation with a table entitled “actual facts”. We are not sure if this is a reference to a belief that CA analysis is wrong or whether they mean that the rest of their consultation does not contain “actual facts”. Perhaps they can clarify.
Our results very clearly contradict EWR Co claims of an advantage for the southern route. In most cases the total reverse is true. For the few remaining counts, the result is broadly balanced. The main reasons for the difference in conclusions are what factors EWR Co have decided to measure, the assumptions they have made and how they have chosen to measure their figures.
Assumptions and Measurement Points
One important assumption that EWR Co have used to underpin their case is that the West Anglia Main Line (WAML) would require to be 4-tracked (increasing the 2 existing tracks to 4) from where a northern approach would join the WAML at Milton and Cambridge. We believe that this would not need be carried out and we will explain our thinking on this in another post. As a result, we have, for some items, provided two counts – one with the 4-tracking (for direct comparison with EWR Co’s own figures) and one without 4-tracking (which we believe is more realistic).
We have also, in some cases, used two measuring points to gain a more accurate assessment of the factors. EWR Co have consistently used only Cambridge station as the basis for comparison between approaches. This may be reasonable for passenger trains but for freight trains, Coldham’s Common is more appropriate since that is the point where freight trains from the two approaches diverge. A freight train is generally accepted to be noisier than an electrified passenger train and just because EWR Co. will not be operating the freight train themselves, it does not mean that the noise will not wake residents in the middle of the night. A map of the area is shown in Figure 1.
EWR Co have said that they have combined the two northern approach options (i.e. freight passing via a new chord just south of Ely and freight passing via a new chord on Coldham’s Common). They have, notably, omitted to mention any of the advantages of the former option in their comparison of factual data. In particular, there would be no impact of freight on Cambridge residents if our first option were adopted and much less overall. For clarity in comparison of numbers, we have used the Coldham’s Common chord option for measurements.
EWR Co recognise that there is little difference (1.1km) between the track lengths of the two approaches for passenger trains measured to Cambridge station. However, the northern approach is over 3km shorter for freight using the Coldham’s Common chord.
Length of infrastructure
While the northern route passes through a greater length of flood zone, it plays this to its advantage by adoption of a trench solution which utilises the buoyancy effect in the waterlogged ground. This results in no viaducts and minimal embankments. It passes beneath roads and the guided busway and could be constructed while keeping the road traffic and guided buses operational. Oddly, when making the comparison, EWR Co have used a similar route to CBRR but, instead of using the CBRR trench construction methodology, they have taken an embankment solution and then proceeded to criticise it. The southern approach has a combined length of over 5km of embankment exceeding 8m in height. The trench approach has been presented on the CBRR website since 2018, so it is strange that EWR Co. do not even comment on it. Did they just miss it? Do they disagree with this widely used approach or are they just looking for reasons to justify a political decision made in favour of the southern approach and find this to be an inconvenient truth?
Impact on residents
This is one of the most important factors between a northern and southern approach, particularly in respect of noise. Night-time noise is clearly more problematic than day-time noise, so we believe that measures appropriate for freight services are more relevant than for passenger services. Although EWR Co have used a variety of assessments, including the length of railway in Cambridge wards, the most direct measure of this is the count of residential properties within 200m either side of the track. The length of track in Cambridge wards is not a very meaningful measurement because in some places the line passes through residential areas and in other places it does not. They have used Cambridge station as the basis for measurements: this is only appropriate for passenger services. We have also considered Coldham’s Common as a basis – see section above on ‘Assumptions and measuring points’. Our figures (which have been assessed by three separate people) are considerably less than those obtained by EWR. However, the absolute numbers are not critical for a comparison – it is the relative numbers between the northern and southern approach that matters. For passenger services the count is similar (slightly in favour of a southern approach) but the critical night-time freight measurement is massively in favour of a northern approach by a factor of over 8:1 (i.e. there are more than 8 times the number of residential properties within 200m of the track on a southern approach than a northern approach).
Roads and other crossings
The number of road and other crossings significantly impacts the overall construction cost of a railway. The greater the span of a bridge, the greater the cost so major road crossings affect the cost more than those for minor roads and farm-tracks. Assuming that 4-tracking will not be undertaken for whichever option is chosen, the overall result is in favour of a northern approach with slightly fewer A- and minor road crossings required. A more significant difference between the approaches is that because the northern approach would pass beneath existing roads, this would result in less temporary traffic disruption during construction and lower noise and visual impacts because of the trench technology.
Measuring distances to environmental sites cannot reveal the whole picture of the impact of the railway on a site. This would partly depend on the wildlife or ecology that the site is trying to protect. For example, the railway following a southern approach can cause a lot of damage to the Wimpole and Eversden Woods SAC but this is not revealed by the measure EWR Co use to show the impact. Although we have compared the approaches using the same measures as EWR Co, they still need to be considered with some degree of caution.
There are 4 SSSIs within a 2km buffer of the southern approach but none on the northern approach. EWR Co have mistakenly measured the northern approach as having 1 within this distance. The one they counted was probably Madingley Woods which is about 2.3km from the northern route.
There are no Special Areas of Conservation (SACs) within any of the buffers used by EWR Co. This does not demonstrate the impact of the Southern Approach on the SAC at Wimpole and Eversden Wood in which a colony of Barbastelle bats roost. The bats forage for around 5-7km from the roosting site and would not be affected by the Northern route. See our previous post on this subject, the Wimpole/Eversdens SAC is one of only Barbastelle SACs in the UK and it is in great danger from EWR Co.’s cavalier assertions about mitigation techniques that have failed in the past and would fail here again
The southern route impacts directly (within about 10m) on 3 scheduled monuments whereas there would be no direct impact with a northern approach. Even using a 2km buffer, the southern route fares worse.
As for other environmental counts, EWR Co have measured two distances from listed buildings to assess the impact of each approach: 10m and 2km, and only using Cambridge station as the measuring point. We consider this to be misleading and have counted listed buildings within three different bands, 10m, 200m and 500m for both passenger trains and freight trains. While EWR Co’s assessment shows broadly similar impacts of both approaches (with a slight disadvantage for the northern route for grade 1 & 2* buildings), our more nuanced and thorough evaluation shows a clear and significant advantage for a northern route, even when considering passenger trains. As mentioned earlier, using Coldham’s Common as a basis for assessment is appropriate for freight trains which cause by far the bulk of noise and air pollution impact on all types of residential property. On this basis, our figures demonstrate that there are more than double the number of grade 1 and 2* properties within 500m of the track on a southern route than on a northern route. The difference is even more stark for grade 2 properties with over 4 times the number within 500m.
EWR Co have counted the number of priority habitats within 10m and 2km of the alignments. This presentation fails to take account of the size of each habitat. To address this omission, we have considered the length of a 200m zone passing through each site[WH1] , as shown schematically below.
Figure 2 Measurement of priority habitats
Although imperfect, it is considered more accurate than EWR Co’s measure. EWR Co’s assessment results in broadly similar outcomes. However, our measure shows the southern route has about a 2.5 times greater impact than the northern route.
Wildlife Trust sites
There is an advantage of the northern route over a southern route (1 site compared to 2 sites within 2km of the routes) but, because the total numbers are low and the 2km distance is great, this is not a differentiating measure.
Local Nature reserves
Our figures are much lower than EWR Co’s figures for both alternatives so it is likely we have not been able to access all the data that EWR Co have used. But taking EWR Co’s numbers at face value, there is a nominal difference slightly in favour of a southern option (12 sites for a northern approach and 10 sites for a southern approach). Again, this is not a differentiating measure.
EWR Co include commercial as well as residential properties in their assessment, whereas we have considered only residential properties. As previously mentioned, they have also assumed that the West Anglia Main Line (Cambridge to Ely line) will be 4-tracked but without providing any supporting evidence. We dispute this assumption and consider that it could be left as a twin track line. Putting this argument to one side, we have looked in detail at EWR Co’s figures. We count 33 residential properties within 10m of the line that could be impacted by a northern approach with 4 tracks between Milton and Cambridge. This compares to 39 for a southern approach. EWR Co, on the other hand, count 40-85 residential and commercial properties close to the line for a northern route and just 5 for a southern route. We have measured to the boundary of a property. While we do not correlate these figures directly with the requirement for demolition, we consider that EWR Co have made some errors in their assessment. For example, there would be about 11 properties that would be directly impacted on just one site at Highfields Caldecote (the Linden development) on a southern approach.
The overwhelming message from our analysis is that on the vast majority of measures, the northern approach is superior to the southern approach, including embankments, residential impact, road crossings and environmental aspects. For the remaining factors, there is a broad similarity between approaches. The measure that EWR Co have ‘afforded particular weight in the back-check undertaken’, the impacts on residential properties, is broadly similar in our assessment even using the doubtful assumption that the northern route will need some 4-tracking.