Saturday, May 24, 2014

How I constructed a small wooden trestle bridge

The bridge leading to the mill siding (see How I constructed the mill siding) was, like the swing bridge (see How I constructed the swing bridge) and two of the locomotives (see How I constructed an 0-6-2T locomotive and How I constructed a 2-4-2T locomotive), inspired by a similar structure on the Southwold Railway. The Southwold original was adjacent to a water mill and so seemed appropriate for my mill siding.
GER drawing of the wooden trestle bridge on the Southwold Railway
The raw material for the bridge was purchased from Wood Supplies, who specialise in supplying wood sections for model makers. Initially, I calculated the scale dimensions of all the timber sections but realised this was making the order far more complicated (and expensive) than was necessary and so I eventually adopted my key principle of over-engineering structures and opted for two sizes of oak timber section -  ½" x ½" and  ½" x ¼" - which were supplied in 18" (450mm) lengths.

Two of the  ½" x ½" timbers were marked out with the positions of the supports. These were chosen quite arbitrarily to coincide with suitable rocky locations on the stream banks for the support footings.

The beams were then positioned beneath the rails and the lengths of the supports marked-out on another piece of ½" x ½" timber.

The sandstone beneath the footings for some of the supports was chiselled out to improve their seating.

The length of each support timber was then shortened by ¼" (the thickness of the narrower timbers which will act as sleepers across the bridge), and sawn off.

 The supports were checked again, in situ and slight adjustments made to ensure they were the right length and shape to fit their locations.

The supports were then glued to the longitudinal beams with exterior grade PVA and held in place with clamps until the glue had entirely set.

The assembly was then placed in position to check clearances.

The central cross-members were then cut to length (85mm) and glued in place. Their location was dictated by the length of the shortest central support timber - the reasoning being that the diagonal bracing timbers would sit at an angle of 45 degrees and hence the horizontal distance along the beam would be the same as the vertical distance for which the brace would provide the hypotenuse (see photo below: X = Y )

Isn't it amazing how many academic disciplines are involved in garden railway modelling? Weights were placed on the timbers while the glue set.

When the glue had set, the length of the diagonals were marked out, using the shortest vertical as the datum .......

..... and the four diagonal braces were cut out from a piece of ½" x ½" timber .....

..... before being glued into placed between the central supports and the cross-members. A further piece of ½" x ½" timber was cut to fit between the cross members and glued into place.

Seven short lengths of ½" x ½" timber were cut out 35mm in length, tapering to 25mm .......

...... and glued behind each of the vertical supports just beneath the longitudinal beams. The eighth was omitted because there was insufficient clearance between the beam and the rock.

Twenty sleepers, 90mm in length, were then marked-out on the ½" x ¼" timber .......

.... and were cut-out. Initially, these were marked at 49mm centres for the track, but later I realised that, as the track over the bridge was slightly curved, I would have to mark the track centres when the bridge was in situ beneath the track.

 These were then glued into place on the longitudinal beams, one sleeper width apart.

 Two sleepers were then trimmed down to 85mm and glued to the central supports, behind the diagonals and beneath the beams.

Once the glue had dried ........

..... the bridge was slotted into place .......

...... and tested, with rolling stock .......

..... and with running water.

At present, the rails have not been fixed to the bridge and the bridge has not been cemented or glued into place in the stream as I want it to remain removable until I have decided whether to add further details. These could take the form of cosmetic brass pins at the joints in the timbers, track spikes and sealing the bridge with stained wood preservative.

Although the original bridge on the Southwold Railway did not include check-rails, I am considering adding them to my bridge as I feel they would add to the bridge's appearance.

Sunday, May 11, 2014

A Day in the Life of Peckforton Station

As this is the first season I am using battery power and radio control, I decided to record a full operating session through a trackside view of movements at the main intermediate station on the railway - Peckforton.

Peckforton Station has a passing loop, two sidings (facing the Up direction) and a single platform on the Down side of the loop. Regular trains to and from the copper mine further Down the line at Bulkeley not only give a rationale for the railway's continuing existence in the 1930s when others have closed, it also creates the need for an operational signalling system. There is a passenger timetable for six passenger trains in each direction on weekdays (based on a timetable from the Southwold Railway), at least one of which is a mixed train (usually the late afternoon train), and there is still sufficient freight traffic to justify a pick-up goods on most days. In between these services, the copper mine ore trains run, usually four in each direction per day (though this varies according to the day's output). This account outlines a typical day's activity at Peckforton Station. It does not include special trains such as excursions, market day specials and special deliveries which I sometimes run during other operating sessions.

Before the first train of the day, farmers start bringing their milk churns for collection by train.

Then, at around 6.45, a Down train of empty skips plus the workmen's coach, hauled by 0-4-0DM loco No. 8, Wynford, arrives to pick up workers for the copper mine. Fortunately, the rich seam of copper provides sufficient employment for the local community and justifies the continuing running of the railway in the straitened times of the early 1930s when the railway is set.

William (Willy) Shaw, the station-master/head porter/signalman arrives to open up the booking office/waiting room/parcels office and catch up with the day's local news before the arrival of the first public train of the day ......

..... the 7:49am Down passenger. This train is hauled by Barclay 2-4-0T loco No. 2, Beeston and includes a flat wagon for transporting milk churns from stations and lineside halts along the line.

After departure, passengers begin arriving for the Up train ........

...... the 9:02 am, which connects with services to Chester and Crewe at Beeston & Tarporley mainline station. The train arrives at around 8:50 am and, while the train takes on passengers and more milk churns,........

...... it is passed by an Up mineral train taking copper ore and spoil from the copper mines to Beeston Market where it will be transferred to standard gauge mineral wagons.

At the rear of the train is the explosives van, used to transport gunpowder to the mine. It is also used occasionally to transport silver ingots from the mine to the end of the line - from time to time silver is found among the seams of copper ore. However, for obvious reasons, there is a tendency to keep these traffic movements low key. So whether the van contains any silver on this train is known to only a few.

At 9:02 precisely, the whistle goes and the Up passenger departs. At around 9:30 am, the Down pick-up goods passes through the station, hauled by ex-Southwold Railway Manning Wardle 0-6-2T loco No. 4, Bulkeley.

At around 10:00am, the Down passenger arrives, which then departs at 10:04 am.

There is a lull, while workers at the timber yard busily offload their raw material from stake wagons and load open wagons with pit-props and sawn timber.

Just before 11:00am, the Up passenger arrives and departs as the 11:07 am.

The next arrival is just after midday, which then departs as the 12:19pm.

At around 12:30pm, the Up pick-up goods steams into the station, having dropped-off and picked-up wagons at Peckforton Mill (see Progress Report 51), then at Bickerton and Bulkeley. Wagon movements are dictated on a weighted random basis by a computer program based on a relational database which I have clumsily programmed myself (see Freight Management on the Railway).

The loco busily shunts wagons in the two sidings while passengers await the arrival of .....

.....the 1:22pm Up passengers service.

 After the passenger train departs, .......

....... there is a little more shunting then the goods train gets the All Clear, and departs.

Just after 2:00pm, a Down train of empty skips passes through, heading for the copper mine.

At 2:39pm, the Down afternoon passenger leaves on its way to Bulkeley.

It returns later as the 4:07 Up passenger.

While awaiting the All Clear, the railway's permanent way trolley passes through on its way down the line.

At around 5:30pm, the Down afternoon mixed train arrives hauled by ex Southwold Railway Sharp Stewart 2-4-2T loco No. 5, Gallantry Bank.  While setting down and picking up passengers .........

....... it is passed by an Up copper ore train.

The mixed departs promptly at 5:42pm. After dropping off and picking up wagons at Bickerton, it returns at around 6.30pm and engages in some shunting, leaving the coaches and their passengers waiting patiently at the platform.

At 6:59pm, it departs for Beeston Castle and Beeston Market stations.

At around 7:20pm, a train of empty skips passes on its way back to the copper mine.

And then, at around 7:40pm, the last Down passenger of the day rolls into the station in the form of the line's Ford(ish) railmotor.

After a pause, the last Up ore train passes through, stopping briefly to deposit local workmen.

The railmotor departs at 7:45pm and returns again at around 8:20pm as the final Up passenger. While waiting it is overtaken by the permanent way trolley and then departs at 8:34pm.

The station then shuts down for the day - awaiting the onslaught of tomorrow's services.