A metroisation proposal for the Great Eastern Main Line

[PTR 444]

With the continuing trend towards metroisation of train services on the UK’s major railways, I’ve been musing about recasting the Great Eastern Main Line, which is a linear route with several branches but lots of irregular stopping patterns. It looks a relatively straightforward route to metroise, hence I have a proposal to standardise stopping patterns so that each station is served by at least 2tph at half-hourly intervals, while prioritising quality connections where direct trains are not possible.

All of my proposed services have a frequency of 2tph, unless otherwise stated:

• London - Norwich express, calling at Stratford, Chelmsford, Colchester, Manningtree (1tph), Ipswich, Stowmarket (1tph) and Diss
• London - Clacton semifast, calling at Stratford, Shenfield, Chelmsford, Beaulieu Park, Witham, Colchester, Colchester Town, then all stations to Clacton-on-Sea
• London - Ipswich stopper, calling at Stratford, Shenfield, then all stations to Ipswich
• London - Southend Victoria turn up and go service, calling at Stratford, Romford, Shenfield, then all stations to Southend (4tph)
• Wickford - Southminster shuttle
• Witham - Braintree shuttle (pending passing loop at Cressing)
• Marks Tey - Sudbury shuttle (1tph)
• Thorpe-le-Soken - Walton-on-the-Naze shuttle
• Manningtree - Harwich Town shuttle

This provides a much simplified service pattern for the Great Eastern region, although there will be some winners and losers. Braintree loses its direct London service, although the doubled frequency should make up for it, especially when tied in with faster connecting London trains at Witham. The big question is whether my proposed London - Clacton service will be workable with 2tph in each direction reversing at Colchester Town, and an end to the long standing cross-platform interchange arrangement at Thorpe-le-Soken to provide for a self-contained, albeit doubled frequency Walton branch.

Even with my metroisation proposal, I respect that there is likely still be demand for direct trains from the branches at peak times, so a separate timetable could account for this period with more emphasis on commuter-style “stopping then fast” service patterns.

 

[JonathanH]

Have you in any way thought about how that would fit on the two track line? I suspect it wouldn't. An all stations stopper between Shenfield and Ipswich would seriously hinder the faster services, and there must be a reason why Norwich services don't now stop at Chelmsford.

Indeed, you only have to look at the down timing of the xx02 to Ipswich, xx18 to Clacton, xx36 to Colchester Town and the xx47 to Braintree to see why those 'turn off' where they do relative to the Norwich services. Would a timetable flighted at xx00 Norwich, xx02 Clacton, xx05 Ipswich then only two Southend departures in between in any way be an improvement on the spacing now, or do you intend looping Ipswich services at Witham?

 

[Magdalia]

With the continuing trend towards metroisation of train services on the UK’s major railways, I’ve been musing about recasting the Great Eastern Main Lin

Metroisation has already been done where it is appropriate, which is London side of Shenfield, and it is called the Elizabeth Line.

It looks a relatively straightforward route to metroise

You haven't looked very carefully. The route beyond Shenfield is not straightforward because you have completely forgotten about freight. The Great Eastern Main Line is one of only two routes for intermodal trains out of Felixstowe. The timetable has to be a compromise between the passenger and freight requirements.

 

[RS465]

Having Clacton services loop into Colchester Town and serving all the shacks after there is such a bad idea. There would be lengthened journey times not only to Clacton, but Hythe for the University of Essex and Wivenhoe.

There would also be a breaking of links from Walton to any major town / city centre. The current set-up works well, with the smaller station between Thorpe-le-Soken and Wivenhoe gets an adequate level of service, albeit with lengthy journeys times to London, while those who want faster journey times from Walton to the GEML can take advantage of the guaranteed cross platform connection at Thorpe-le-Soken, where the trains pull in at the same time.

I also wouldn’t break links from Braintree to Chelmsford and London.

 

[PTR 444]

Have you in any way thought about how that would fit on the two track line? I suspect it wouldn't. An all stations stopper between Shenfield and Ipswich would seriously hinder the faster services, and there must be a reason why Norwich services don't now stop at Chelmsford.

Indeed, you only have to look at the down timing of the xx02 to Ipswich, xx18 to Clacton, xx36 to Colchester Town and the xx47 to Braintree to see why those 'turn off' where they do relative to the Norwich services. Would a timetable flighted at xx00 Norwich, xx02 Clacton, xx05 Ipswich then only two Southend departures in between in any way be an improvement on the spacing now, or do you intend looping Ipswich services at Witham?

Metroisation has already been done where it is appropriate, which is London side of Shenfield, and it is called the Elizabeth Line.


You haven't looked very carefully. The route beyond Shenfield is not straightforward because you have completely forgotten about freight. The Great Eastern Main Line is one of only two routes for intermodal trains out of Felixstowe. The timetable has to be a compromise between the passenger and freight requirements.

These are very good points. Perhaps an alternative could be to keep the skip-stopping patterns to Colchester, but metroise them in the sense that each stopping pattern is roughly 15 minutes apart, and flight the fast Norwich trains in between.

For example:

2tph to Norwich. Fast to Colchester then Ipswich, Stowmarket (1tph), Diss and Norwich.

2tph to Ipswich. Fast to Chelmsford then all stations to Ipswich.

2tph to Clacton. Semi-fast calling at Shenfield, Ingatestone, Chelmsford, Beaulieu Park, Witham, Colchester, Colchester Town (reverse), then all stations to Clacton-on-Sea.

All trains also call at Stratford (London).

 

[47421]

Another important consideration is whether a new timetable works in both the up and down direction. Other contributors have flagged before that a TT might work well in one direction but terminus platform capacity & turnaround times & unit & staff diagrams mean it cannot in practice be implemented in the other direction in the same way

 

[Magdalia]

metroise them in the sense that each stopping pattern is roughly 15 minutes apart, and flight the fast Norwich trains in between.

For example:

2tph to Norwich. Fast to Colchester then Ipswich, Stowmarket (1tph), Diss and Norwich.

2tph to Ipswich. Fast to Chelmsford then all stations to Ipswich.

2tph to Clacton. Semi-fast calling at Shenfield, Ingatestone, Chelmsford, Beaulieu Park, Witham, Colchester, Colchester Town (reverse), then all stations to Clacton-on-Sea.

It is hard to see how this improves on the current timetable, apart from looking neat and tidy for someone a long way away.

It is important to remember that Chelmsford is the third busiest station in the East of England, after Cambridge and Stansted Airport, and that, of station to station flows with one station outside London, Chelmsford-Liverpool Street is 9th in the ranking, just behind Cambridge-Kings Cross.

The current timetable cleverly delivers that 4tph turn up and go service between Chelmsford and Liverpool Street, that you think is so important, on the route's biggest traffic flow. Ignoring the Norwich trains, Chelmsford has off peak departures for Liverpool Street at xx11 ex Colchester Town, xx25 ex Braintree, xx41 ex Ipswich and xx55 ex Clacton. Going the other way are xx02 to Ipswich arr xx34, xx18 to Clacton arr xx52, xx36 to Colchester Town arr xx08 and xx48 to Braintree arr xx23.

I know all of this because I use it about once a month.

So you start by wrecking the Chelmsford 4tph turn up and go service. You cut the Braintree branch off not just from Liverpool Street and Stratford but Chelmsford too. You add 10 minutes onto the Clacton journey time. It really is hard to see anything to like here.

 

[Technologist]

Metroisation has already been done where it is appropriate, which is London side of Shenfield, and it is called the Elizabeth Line.


You haven't looked very carefully. The route beyond Shenfield is not straightforward because you have completely forgotten about freight. The Great Eastern Main Line is one of only two routes for intermodal trains out of Felixstowe. The timetable has to be a compromise between the passenger and freight requirements.

Pretty simple do an economic assessment of freight trains vs passenger trains and chuck the one that loses off the tracks.

A passenger train can take hundreds of cars off the roads a freight train takes 30 lorries off, an HGV is only worth 2 cars from a congestion stand point.

 

[Jaydubya]

It is hard to see what problem this is trying to solve. Greater Anglia has been doing well in terms of demand recovery. There is still potential to lengthen services with all the rolling stock ordered.

The Southend Victoria 4tph off peak was in the Abellio bid so presumably this could be delivered with the rolling stock available. Would require a tweak to Southminster services to every 45mins which already happens when they run this service during engineering work on the line via Chelmsford.

Shenfield, Billericay and Wickford already see a turn up and go at peak times.

 

[Magdalia]

A passenger train can take hundreds of cars off the roads a freight train takes 30 lorries off, an HGV is only worth 2 cars from a congestion stand point.

Only if the trains are full. Most intermodals that I see when I go to Chelmsford are fully loaded, most off peak passenger trains that I travel on have loads of spare capacity. The passenger trains are only full in the peaks.

 

[CMS1]

IMO Greater Anglia is a well run TOC with few delays. There is often congestion and slow running between LST and Shenfield but this is built into the timetable.

Even if the suggestion could fit, it will upset a lot of people. As we know the British want direct trains, and that's not going to change however much its disagreed with on the forum. Effectively people view it as 2 journeys and if the 1st part is more effective by car, they'll drive that part. Some might try the Witham shuttle for a few days, until they miss shuttle home and spend 45 mins getting from Witham to Braintree. The Clacton branch would also be stuffed. Take Wivenhoe for example, the morning train is already 1hr15 compared to 50 mins from Colchester North. Add on an extra 11 mins for a Colchester Town reversal, a lot of Wivenhoe people will drive 5 miles to Colchester instead. Walton folk can't even get to Colchester without changing. Consequently it will just take people from the railway onto the roads, not something anyone wants.

 

[Technologist]

Only if the trains are full. Most intermodals that I see when I go to Chelmsford are fully loaded, most off peak passenger trains that I travel on have loads of spare capacity. The passenger trains are only full in the peaks.

Reasonable, however as a approximation a freight path tends to take two or more passenger paths off so in that circumstances we probably only need 10's of passengers on a train to make passenger path more valuable from a capacity stand point. Also with relaxed planning requirements passenger traffic has in the long term greater potential to induce demand than freight paths.

I suspect that once you include induced demand and the potential to run many more paths on a non mixed railway line the gross value add for a passenger train will be much higher than for a freight train. We certainly should move to a point where freight vs passengers is addressed using this metric.

This is some work done by Centre for Cities looking at stations which are 45 minutes from a major city terminal which could be surrounded by dense developments which would allow for far more new homes to be built where people want them. The property value uplift can then be captured and put into metroising the service.

It can be seen on the Great Eastern line that the stations that could be metroised go out to nearly Colchester, though if the line was metroised and we used battery EMU's we could move that commuting radius out even further due to faster accelerating trains and line speed improvements.

The question would then be if the service level was increased to metro like levels would we get enough service all the way out to Ipswich to justify the metro and once we started to induce demand and thus building would we start to see more trips between stations on the line and to some of the other centres like Colchester and Ipswich.

 

[Magdalia]

Reasonable, however as a approximation a freight path tends to take two or more passenger paths off so in that circumstances we probably only need 10's of passengers on a train to make passenger path more valuable from a capacity stand point. Also with relaxed planning requirements passenger traffic has in the long term greater potential to induce demand than freight paths.

I have some sympathy with this view, but we can only start from where we are now.

Where we are now is that the UK imports lots of manufactured goods, Felixstowe is the most important point of entry, and 29% of containers at Felixstowe move by rail, either via the GEML or cross country.

Rail Freight at Port of Felixstowe | Three Dedicated Rail Terminals

Port of felixstowe is Britain’s biggest and busiest rail freight port. A million TEU of container traffic are moved annually.

www.portoffelixstowe.co.uk

A million TEU of container traffic are moved annually through the three rail terminals at Felixstowe. This saves over 100 million HGV miles each year, reducing road congestion and improving environmental performance.

Rail volumes account for around 29% of the port’s total UK domestic throughput, rising to 50% of traffic to the North and West Midlands.

Turfing the freight off the GEML would be hugely damaging to supply chains and the UK economy.

It can be seen on the Great Eastern line that the stations that could be metroised go out to nearly Colchester, though if the line was metroised and we used battery EMU's we could move that commuting radius out even further due to faster accelerating trains and line speed improvements.

The most important stations, Chelmsford and Colchester, already have 4tph services off peak, as does Witham, and more trains in the peak. The existing peak time flows to London are well below pre-pandemic levels, and new trains mean that there is spare capacity. The new station at Beaulieu Park opens soon. The impact of more passenger trains is going to be marginal, given the existing provision.

Battery EMUs are irrelevant in this instance because all relevant lines are electrified.

This is some work done by Centre for Cities looking at stations which are 45 minutes from a major city terminal which could be surrounded by dense developments which would allow for far more new homes to be built where people want them. The property value uplift can then be captured and put into metroising the service.

This argument is frequently wheeled out with reference to Cambridge. I'm sceptical that property value uplift can be captured, and suspicious that its proponents spend the supposed bounty many times over. Public transport won't be the only claimants on that bounty, and, in the East of England they won't be top of the pile, because water comes first.

 

[JCO1406]

Sorry to be that guy, but Chelmsford gets 5tph off peak, 1tph Norwich stops there, however it does not call at Stratford. The other Norwich train stops at Stratford and skips Chelmsford. During peak, most Norwich trains skip Chelmsford. I know this as I used to live on the GEML, and I still do travel often on it.

 

[Magdalia]

Sorry to be that guy, but Chelmsford gets 5tph off peak, 1tph Norwich stops there

I deliberately left the Norwich trains out because they don't add to service frequency. On the up road the other 4tph are all 14-16 minutes apart, on the down road the other 4tph are all 12-18 minutes apart.

 

[Class15]

Only if the trains are full. Most intermodals that I see when I go to Chelmsford are fully loaded, most off peak passenger trains that I travel on have loads of spare capacity. The passenger trains are only full in the peaks.

Did you see these Felixstowe trains before or after the end of March?

Since Maersk pulled out most of the intermodals, particularly Freightliner, to/from Felixstowe have been very poorly loaded, even accounting for the reduction in number.

 

[Farigiraf]

With the continuing trend towards metroisation of train services on the UK’s major railways, I’ve been musing about recasting the Great Eastern Main Line, which is a linear route with several branches but lots of irregular stopping patterns. It looks a relatively straightforward route to metroise, hence I have a proposal to standardise stopping patterns so that each station is served by at least 2tph at half-hourly intervals, while prioritising quality connections where direct trains are not possible.

All of my proposed services have a frequency of 2tph, unless otherwise stated:

• London - Norwich express, calling at Stratford, Chelmsford, Colchester, Manningtree (1tph), Ipswich, Stowmarket (1tph) and Diss
• London - Ipswich stopper, calling at Stratford, Shenfield, then all stations to Ipswich

Manningtree always has a healthy load get on/off the Norwich service, partly because there are good connections to Mistley and Harwich. Halving the fast service to London, even if it's a net gain of 1tph, would likely result in most people effectively treating Manningtree station as having 1tph, aiming for the fast service rather than the slow all shacks service (and a 745 is much better than a 720 for a journey of over an hour to London). Arguably curtailing the Ipswich stopper at Colchester or Colchester Town may even be more useful overall.

Marks Tey - Sudbury shuttle (1tph)

This could go to Colchester (the South facing bay platform) if there is capacity, or to Town to make it a turn up and go service between Colchester Town and Colchester (North). Considering that it uses Bi-modes, I wonder why it doesn't do this all day nowadays.

Thorpe-le-Soken - Walton-on-the-Naze shuttle

This is effectively what it is at the moment for passengers from the Walton branch to anywhere past Wivenhoe, due to an excellent cross-platform connection. While your proposed doubled frequency service is great, it would come at the expense of the connecting service (from Clacton) becoming at least 20 minutes slower to Colchester. Additionally, 2tph is probably overkill for Weeley and maybe Great Bentley/Alresford unless new housing is built nearby.

 

[NCT]

Whatever for? For an outer suburban railway the GEML has a reasonably good timetable, at least in the off-peak. The peak timetable is a bit messy and could do with a bit of standardisation, and perhaps expanding of the peak service pattern to be more than just the high peak hour, but that would be about it.

It don't see what's to be gained by depriving Braintree of its direct London service. East of Witham doesn't need that many trains and the Braintree service provides a capacity boost to west of Witham which has a bit more civilisation.

The Norwich services don't really want to have different stopping patterns east of Colchester. A perfectly half-hourly service provides a good basis for an Anglia taktfarhplan. I can accept the current practice of one stopping at Stratford and one stopping at Chelmsford because there are sufficient other services providing clockface services (so the odd Stratford and Chelmsford calls in the Norwich services are a bonus on top).

Then that leaves a 4tph pattern all calling at Shenfield, Chelmsford, Witham and Colchester giving them all a roughly every 15-minute service, which is a good off-peak service level.

This then leaves Ingatestone, Beaulieu Park, Hatfield Peverel, Kelvedon and Marks Tey, which don't need more than 2tph. If the Dec 25 timetable has room for further standardisation, then I would suggest

- One pair of services calling at Ingatestone, Beaulieu Park and Hatfield Peverel, and I would suggest the Braintree and Colchester Town
- One pair of services calling at Kelvedon and Marks Tey, which would be the Clacton and Ipswich.

Then some sort of takt plan at Colchester and Colchester town so that London - Colchester Town has an interchange opportunity in the other half hour, there's an hourly cross-platform interchange for Walton, and maybe there's an interchange opportunity in the other half hour for London - Clacton as well. I haven't quite worked out a service pattern that A) has convenient timings and B) doesn't represent an overprovision of trains.

If one is 'allowed' to entertain some moderate infrastructure enhancements for a nicer peak timetable, then I'd suggest
- 2tph Norwich first stop Colchester
Following all call at Stratford, Shenfield, Chelmsford and Colchester if they go through
- 2tph Braintree (needs a loop?) calling at Ingatestone, Beaulieu Park, Hatfield Peverel and Witham
- 2tph Clacton (or 1 each to Clacton and Walton), calling at Kelvedon and Marks Tey
- 2tph, 1tph each to Ipswich and Harwich

(Not sure if the above represent an upgrade or a downgrade from the Dec 2025 peak service level - if downgrade then some of my 1tph can be boosted to 2tph)

The above timetable may require some or all of the following in order to work - I'm describing the down pattern, the up pattern would be symmetrical
- Beaulieu Park with timetabled overtaking moves
- Braintree service departing Witham on platform 4 with the next Norwich service passing through on platform 3 just 2 minutes later
- Clacton / Walton service departing Colchester on platform 1 with the next Norwich service arriving on platform 2 just 2 minutes later

 

[BerkshireRails]

London - Southend Victoria turn up and go service, calling at Stratford, Romford, Shenfield, then all stations to Southend (4tph)

Just extend Elizabeth Line to Southend and use the freed up paths for other services. That I see as being most likely.
It is 3 paths an hour each way.

 

[NCT]

Just extend Elizabeth Line to Southend and use the freed up paths for other services. That I see as being most likely.

How is that benefiting anyone?

 

[BerkshireRails]

How is that benefiting anyone?

It is providing a turn up and go service for Southend as well as providing extra capacity on the GWML to Chelmsford and beyond as well as removing the every 20 minute service pattern when everything else seems to be every 30 or 60 minutes.

 

[CMS1]

It is providing a turn up and go service for Southend as well as providing extra capacity on the GWML to Chelmsford and beyond as well as removing the every 20 minute service pattern when everything else seems to be every 30 or 60 minutes.

I doubt the Southend branch commuter towns would appreciate their service being an all stops?

 

[NCT]

It is providing a turn up and go service for Southend as well as providing extra capacity on the GWML to Chelmsford and beyond as well as removing the every 20 minute service pattern when everything else seems to be every 30 or 60 minutes.

The every 20 minute pattern is only off-peak where there is spare track capacity.

Elizabeth line's Shenfield capacity is fixed at 12tph (plus up to 4tph peaks from high-level). Why would you compress 6tph worth of passengers (Southend is 6tph in the high peak) onto the already full-and-standing Elizabeth line? And adding 25 minutes to Southend journeys and a train with no bogs?

 

[CMS1]

One of the Norwiches could be replaced by 3 Flirts (which you sometimes see running), with 1 splitting at Ipswich for Lowestoft and 2 continuing to Gt Yarmouth. They would terminate and return at approx the same time. Plus a Saxmundham to Sizewell shuttle bus (there is now hundreds of cars daily to Sizewell, the A12 north of Ipswich is fairly chaotic, and the road improvements coming are pretty insufficient).

 

[Class15]

It is providing a turn up and go service for Southend as well as providing extra capacity on the GWML to Chelmsford and beyond as well as removing the every 20 minute service pattern when everything else seems to be every 30 or 60 minutes.

Why would Southend line commuters appreciate such a big increase in journey times?

 

[Bald Rick]

Just extend Elizabeth Line to Southend and use the freed up paths for other services. That I see as being most likely.
It is 3 paths an hour each way.

It’s not likely at all. Indeed it’s not going to happen.

 

[William3000]

With the continuing trend towards metroisation of train services on the UK’s major railways, I’ve been musing about recasting the Great Eastern Main Line, which is a linear route with several branches but lots of irregular stopping patterns. It looks a relatively straightforward route to metroise, hence I have a proposal to standardise stopping patterns so that each station is served by at least 2tph at half-hourly intervals, while prioritising quality connections where direct trains are not possible.

All of my proposed services have a frequency of 2tph, unless otherwise stated:

• London - Norwich express, calling at Stratford, Chelmsford, Colchester, Manningtree (1tph), Ipswich, Stowmarket (1tph) and Diss
• London - Clacton semifast, calling at Stratford, Shenfield, Chelmsford, Beaulieu Park, Witham, Colchester, Colchester Town, then all stations to Clacton-on-Sea
• London - Ipswich stopper, calling at Stratford, Shenfield, then all stations to Ipswich
• London - Southend Victoria turn up and go service, calling at Stratford, Romford, Shenfield, then all stations to Southend (4tph)
• Wickford - Southminster shuttle
• Witham - Braintree shuttle (pending passing loop at Cressing)
• Marks Tey - Sudbury shuttle (1tph)
• Thorpe-le-Soken - Walton-on-the-Naze shuttle
• Manningtree - Harwich Town shuttle

This provides a much simplified service pattern for the Great Eastern region, although there will be some winners and losers. Braintree loses its direct London service, although the doubled frequency should make up for it, especially when tied in with faster connecting London trains at Witham. The big question is whether my proposed London - Clacton service will be workable with 2tph in each direction reversing at Colchester Town, and an end to the long standing cross-platform interchange arrangement at Thorpe-le-Soken to provide for a self-contained, albeit doubled frequency Walton branch.

Even with my metroisation proposal, I respect that there is likely still be demand for direct trains from the branches at peak times, so a separate timetable could account for this period with more emphasis on commuter-style “stopping then

== Doublepost prevention - post automatically merged: 1 Sep 2025 ==

Interesting - but I don’t think the fastest trains to Norwich should stop at Stratford and Chelmsford, which have multiple stops.

I would have

London Liverpool Street, Colchester, Ipswich, Diss, Norwich


London Liverpool Street, Colchester, Manningtree, Ipswich, Stowmarket, Diss, Norwich


Long distance services shouldn’t be stopping at Chelmsford and Stratford. Midland Mainline trains to Nottingham - a similar distance don’t stop at places like St Albans and Luton Airport, and Luton.

 

[CMS1]

Although there is a difference in that Stratford is a major hub for connections in London, sometimes a good third of the train empties there, or at least the carriage I'm in!

 

[William3000]

It is hard to see how this improves on the current timetable, apart from looking neat and tidy for someone a long way away.

It is important to remember that Chelmsford is the third busiest station in the East of England, after Cambridge and Stansted Airport, and that, of station to station flows with one station outside London, Chelmsford-Liverpool Street is 9th in the ranking, just behind Cambridge-Kings Cross.

The current timetable cleverly delivers that 4tph turn up and go service between Chelmsford and Liverpool Street, that you think is so important, on the route's biggest traffic flow. Ignoring the Norwich trains, Chelmsford has off peak departures for Liverpool Street at xx11 ex Colchester Town, xx25 ex Braintree, xx41 ex Ipswich and xx55 ex Clacton. Going the other way are xx02 to Ipswich arr xx34, xx18 to Clacton arr xx52, xx36 to Colchester Town arr xx08 and xx48 to Braintree arr xx23.

I know all of this because I use it about once a month.

So you start by wrecking the Chelmsford 4tph turn up and go service. You cut the Braintree branch off not just from Liverpool Street and Stratford but Chelmsford too. You add 10 minutes onto the Clacton journey time. It really is hard to see anything to like here.

Chelmsford is busy but the main flows are towards London. St Albans City is a comparable station on the Midland Mainline - it’s busier than Leicester and Derby but nobody is suggesting fast trains to Nottingham (a similar distance from London as Norwich) should stop there. Chelmsford can be served very well by semi fast trains to Braintree, Ipswich, and Clacton giving it a good frequency. And for the fairly small numbers travelling north east to East Anglia, a straightforward change at Colchester should suffice

 

[BerkshireRails]

It’s not likely at all. Indeed it’s not going to happen.

That is the most likely option as it was proposed during the design phase of the Elizabeth Line. I say it probably has <5% chance of happening.