The story of the CSLR so far, 2011
Click on the pictures for larger images.
Over the winter of 2010/2011 the brickwork around the pond suffered badly, the snow and ice got in between the two layers holding the butyl liner and upon freezing, pushed them apart. Unfortunate as the CSLR rails were laid along the top. They had to come up.
Such a large operation prompted a change. I would construct a new bridge to cross the pond rather than go around it and whilst i was at it, ease the curves on that side of the garden. Spurred on by bridgework on the South Don and Flingel Railway in Lymmington, I decided that a model of a bridge from my home town of Sunderland would be good so undeterred by the fact that the original is now a road bridge I embarked on a model of the Wearmouth Bridge.
The span is a full 2m, the deck is constructed from a flat piece of aluminium with angle stiffeners, rivetted together; the arches are made from 12mm square section plastic piping welded together and the support wires are varying lengths of bicycle spokes.
Build was completed by constructing the four quarter arches to a full size plan drawn out using CAD onto A3 sheets, pinned to a board. The plastic tube was cut through all bar one side, bent and the resulting gap filled with a fillet piece, all welded with PVC Pipe glue. The cross pieces within the arches are sides of the tube, made by running the tube offcuts through a bandsaw.
The four quarters were bolted to the deck assembly and the
top hinge welded into place when all was square. The cross pieces were then
added.
To fit the support wires, pockets had been added to the
arches using more of the square tube. With the bridge inverted, the spokes were
dropped through pre-drilled holes in the deck and the spoke nipples sat in the
pockets.
The
pockets were then filled with epoxy, making sure the spokes could still be
unscrewed and the whole lot left to dry. When the epoxy had cured, the spokes
were unscrewed and cut to length. The innards of electrical connector blocks are
used to secure the lower ends whilst retaining a degree of adjustment.
Finally, the deck was primed with uPol Acid Etch #8 and
the plastic with Halfords Plastic Primer. Then the deck was given several coats
of satin black and the superstructure several coats of Rover Damask Red.
Meanwhile, the abutments were prepared.
The
level of water in the pond had been lowered to correct the problems with the
brickwork and lift the track. At the same time, the brickwork was replaced with
more natural looking stone and using breeze blocks, fast setting cement and a
cold chisel, the abutments were fashioned using a dummy bridge made from a spare
decking plank. This made sure the ends were level with each other and square.
The deck of the new bridge is
about 50mm higher than the old trackbed. This means that the trackbed leading to
and from the bridge needed lifting by the same amount to match.
Taking
advantage of this, the trackbed below this level was all raised to suit. This
meant that from before the end of the long straight was raised, the curve by the
water butt radius eased out to 6 feet at the same time and the track relaid.
On
the other side of the bridge, the trackbed was raised all the way to the tunnel
and through to the halt, easing the curves all the way
.
The
old blue bridge was refurbished, painted to match the new bridge and re set on
the approach to the new bridge.
The
gap it once spanned was filled with a granite sett cob.
