The Anonymous Widower

More On Discontinuous Electrification In South Wales

In the July 2018 Edition of Modern Railways, there is an article entitled KeolisAmey Wins Welsh Franchise.

This is said about the electrification on the South Wales Metro.

KeolisAmey has opted to use continuous overhead line equipment but discontinuous power on the Core Valley Lnes (CVL), meaning isolated OLE will be installed under bridges. On reaching a permanently earthed section, trains will automatically switch from 25 KVAC overhead to on-board battery supply, but the pantograph will remain in contact with the overhead cable, ready to collect power after the section. The company believes this method of reducing costly and disruptive engineering works could revive the business cases of cancelled electrification schemes. Hopes of having money left over for other schemes rest partly on this choice of technology.

Other points made include.

• A total of 172 km. of track will be electrified.
• The system is used elsewhere, but not in the UK.
• Disruptive engineering works will be avoided on fifty-five structures.
• Between Radyr and Ninian Park stations is also proposed for electrification.

Nothing is said about only electrifying the uphill track, which surely could be a way of reducing costs.

Ystrad Mynach To Rhymney

The article also states that on the Rhymney Line, the section between Ystrad Mynach and Rhymney stations will be run on batteries.

• The distance is about ten miles.
• The altitude difference is is about 125 metres.
• The station area at Rhymney station will be electrified.
• Rhymney will be an overnight stabling point.
• Trains will change between overhead and battery power in Ystrad Mynach station.
• Trains could charge the batteries at Rhymney if required.

Effectively, there is a avoidance of at least fourteen miles of electrification.

• Four miles of double track between Ystrad Mynach and Bargoed.
• Six miles of single track between Bargoed and Rhymney.

But as Rhymney to Ystrad Mynach currently takes about fourteen minutes, there will have to be some extra double-track, so that the required frequency of four trains per hour (tph) can be achieved.

None of this extra track will need electrification.

As the trains working the Rhymney Line will be tri-mode Stadler Flirts, with the capability of running on electricity, diesel or battery, I don’t think that KeolisAmey are taking any risks.

The Merthyr Line

The Merthyr Line splits North of Abercynon station into two branches to Aberdare and Merthyr Tydfil stations.

• South of Abercynon the branch is double-track.
• Both branches are single track.
• The Aberdare branch is about eight miles long.
• Aberdare is around 40 metres higher than Abercynon.
• Trains take 27 minutes to climb between Abercynon and Aberdare stations and 21 minutes to come down.
• The Merthyr Tydfil branch is about ten miles long
• Merthyr Tydfil is around 80 metres higher than Abercynon.
• Trains take 27 minutes to climb between Abercynon and Merthyr Tydfil stations and 21 minutes to come down.

If the proposed four tph are to be run on these branches, there would need to be some double-tracking North of Abercynon.

Will both tracks be electrified, or will it be possible with just electrifying the uphill track?

The Rhondda Line

The Rhondda Line splits from the Merthyr Line to the North of Pontypridd station and goes North to Treherbert station.

• South of Porth station, the line is double-track.
• North of Porth station, the line is single-track with a passing loop at Ystrad Rhondda station.
• Treherbert is 90 metres higher than Porth..
• Trains take 28 minutes to climb between Porth and Treherbert and 20 minutes to come down.

If the proposed four tph are to be run on this branch, there may need to be some double-tracking North of Porth.

Will both tracks be electrified, or will it be possible with just electrifying the uphill track?

Conclusion

I suspect there’ll be more savings, as the engineers get to grips with the capabilities of battery trains and discontinuous electrification.

As I said, will it be necessary to electrify downhill tracks?

The tri-mode Stadler Flirts and the Stadler Citylink Metro vehicles could use regenerative braking to their batteries.

The use of gravity in this way to charge the batteries, would increase the efficiency of the South Wales Metro.

June 28, 2018 - Posted by AnonW | Transport/Travel | Discontinuous Electrification, Electrification, Rhondda Line, Rhymney Line, South Wales Metro, Stadler Citylink Metro Vehicle, Tri-Mode Stadler Flirt