Playing Trains

While a lot of work was done today on landscaping, electrical, viaduct and general tidying up, I also spent some time unashamedly playing trains.

37406 on the viaduct.

37406 "The Saltire Society" on the viaduct with a ballast train.

37406 emerges from the tunnel

60163 "Tornado" bursts out of the tunnel.

Tornado passes 37406.

37406 from Tornado's train

L&Y "Pug" 0-4-0ST

GWR 0-4-2T

Single-coach diesel unit with Hen Day headboard.

Hen Day special behind 75073.

Hen Day special behind Percy.

... and just to show we run freight trains too...

A rather grimy Stanier 8F leaves the tunnel on a short freight.

A freight train climbs past the quarry towards the tunnel.

A freshly-repainted Jinty banks a train into the tunnel.

The Tunnel

Today, work started in earnest on construction of the tunnel. The site was dug out, hardcore tamped in, and a level bed of conctrete laid. This will provide support for two rows of two building blocks, with a space beween them for the tunnel lining. The blocks will support removable paving slabs at the surface of the path.

On emerging from  the tunnel, the line will curve round to the left.

The tunnel construction site.

Having started tunnel construction, there is a need to get it finished as soon as possible to allow the path to be re-opened. Hence, today the removable treads and their supports were installed, and made good for tomorrow's predicted rain. With the engine in front of it it appears much bigger than necessary, but it will be better when it is landscaped and the portals fitted.

A short construction train simmers by the tunnel entrance, while a mechanical digger prepares the site.

The tunnel trackbed was in place today, and temporary track was again laid to ensure levels and gradients appeared correct. 9F no 92203 had the honour of heading the test train, with the portal (part detailed and unpainted) and a retaining wall in place. These are based on the south portal of Combe Down tunnel, Bath. The change of gradient from 1 in 50 to about 1 in 100 in the tunnel is clearly visible in the picture. It's perhaps rather sudden and will be smoothed in in the final trackwork.

A 9F emerges from the tunnel with a train.

(Sunday 21/8) The track is now laid through the tunnel, the tunnel liner is in place and the cavities filled with foam, and some outside landscaping is complete.

A 4F takes a train into the tunnel.

Penny assists with load-testing of the path over the tunnel.

Extending up the hill

The trackbed running up the hill from the viaduct to the tunnel was pretty well ready for tracklaying, so I thought I'd better get on with it while the weather was good. As I intended to include a turnout for a possible future quarry siding, I decided to firstly check that the layout of the siding is feasible. This I did with a few old bits of track, laid temporarily in place.
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Trying out a potential layout for a quarry siding.

By close of play, I had about three metres of track laid and ballasted, including a turnout for the quarry, and with electrical feeds soldered in place where necessary. Between the viaduct and the turnout will be a station platform long enough for 3 or 4 coach local trains, and for this reason the gradient eases to almost level for a short distance above the viaduct.

The new section of track, waiting to be tidied up.

Next day, the ballasting and wiring was completed on the new section. The first train through after the engineering work was a local train pulled by "Tangmere", seen here arriving at the station.

"Tangmere" slows for the station.

"Tangmere" continues up the hill towards the tunnel.

A further 2 metres of track have now been laid, right up to the site of the tunnel entrance. A BR standard 4MT 4-6-0 no. 75073 takes a local train up the new section.

4MT 4-6-0 75073 approaches the tunnel.

Meanwhile, the civil engineers are busy preparing for the tunnel. It will be built under a path using the cut-and-cover technique, with the top removable for maintenance. The portals will be based on Combe Down tunnel. The picture shows the initial stage of construction of the lower entrance, based on Combe Down south portal.

The basic structure of the tunnel entrance, based on Combe Down south portal.

Good news & Bad news

The good news is that I have done a lot more testing, run trains over the viaduct (on the final trackbed but with temporary track), and extended the trackbed up to the tunnel entrance.

One of the tests involved running a train up the steepest section, with increasing numbers of coaches, with and without a pilot. Without a pilot, the best it could do was 4 before it started losing traction on the rails.With a pilot, they managed 8, still with some slipping from Tangmere. I stopped at 8, when smoke started coming out of the pilot engine! (...and it wasn't the paintshop smoke seen in the pictures below.)

34067 "Tangmere" piloted by 2P 40579 (still in LMS livery) on a heavy cross-country train.

40579 and 34067 approach the viaduct, working hard up the gradient.
The troublesome increase in gradient can be seen between the green and red/cream coaches.

4F 44417 on the viaduct with an anachronistic ballast train.

View from a 00 microlight above the viaduct, looking along the trackbed towards the site of the tunnel mouth.

And the bad news? Well, the poor performance of the locos on the steepest gradient is the clue. I re-checked the gradient and found I had been somewhat over-optimistic in the measurements during construction, and instead of 1 in 50 with a short stretch of 1 in 40, I had about 2 metres of 1 in 40 with a short stretch of 1 in 33. This makes a big difference to the length of trains that can be handled.

What am I going to do about it? For now, I'll leave the track in place but won't extend it to double track. This will allow trains to be run and the weather-resistance of the track to be tested. Any new track further down-hill will have the trackbed raised so that eventually the existing track can be replaced with a maximum gradient of 1 in 50, as originally intended. The viaduct and the stretch up to the tunnel do not exceed 1 in 50.

Tracklaying at last!

I spent this afternoon laying the first permanent track for the garden railway. The first three metres went well, then I found an uneven bit of trackbed and had to do some rework. Before locking up, I ran a couple of trial trains on the first three metres (gradient about 1 in 40). Note the prototypical superelevation on the curve.

A Railway in the Garden

After watching James May's second (this time successful) attempt at running a Hornby train to Barnstaple, the idea formed for a railway in the remoter parts of our garden. An initial survey showed that a gradient would be necessary, and after tests with several engines and up to 12 coaches, 1 in 50 was chosen as the ruling maximum, with short stretches of 1 in 40. The first picture shows the gradient trials under way, with a 9F pulling 8 coaches up 1 in 40.

It wasn't long before a brick embankment had appeared.  A removable section is required, in front of the gate, achieved with a plywood viaduct.

To check out the basic construction techniques, a short section of temporary track was laid.

... followed by a test with the part-completed viaduct, to assess whether a sound-deadening underlay is needed.