Maintenance

Inspector's train

We recently took delivery of a modified Planet and carriage so that our "track inspector" can drive around and "inspect" the track. The order was complicated by the fact we needed the train to suit the 134mm gauge track. Roger Jones delivered the train and we did a test to make sure the modifications were correct.

After the handover and a demonstration of preparing and driving the train our track inspector took the train for an extended run around the track. These new Planets have regenerative braking and improved electronics.

The amazing thing is that this tiny loco can pull two people around the track. This is amazing because the loco weighs little and the driving truck is heavy due to the 120AH battery under the seat. For extra comfort the Planet even manages an extra carriage sometimes and runs in reverse.

Yard clearing

Back in 2016 most of the property was covered in privet and dead branches and leaf litter. Most of this was cleared after the bamboo was felled. This effort took months and many hours with a small mulcher.

One outstanding issue was some tall trees that were too close to the house. These trees have accelerated the rotting of the barge boards and blocked access between the house and the bridges. Recently (Nov 2017) I spoke to a tree man who said he could remove one of the trees. I accepted his quote for the job. He also offered to fell two dead trees but rather than paying him I decided to fell them myself. The first one had to come down across the track so I protected the track panel before cutting the trunk and using the winch to fell the tree. The second tree was a large palm tree which just required notching and winching to fell it.

The next week a tree climber visited and cut and dropped the tree near the crossing sign. I'd covered the nearby track with planks in case any bits fell on the track but this was unnecessary as all pieces fell in the small drop zone between the tree and the trestle bridge. There was some damage to the large camellia next to this tree so we had to cut one of its branches.

While the climber was here I asked about removing some trees on the south side of the house. Two trees were very close to the house and two more were a little farther away. One was more than 3 metres away but it was dead and okay to remove without council permission. There were also four dead palm trees. The climber removed three of the four trees and then we felled the dead one. The next day I cut the four palm trees and pulled them down with the winch.

The final task here was to get the stumps ground and then level the area so I can get cars and other vehicles through the area to access the front yard. The cleared area still needs more levelling and packing and hopefully grass will grow here in the future. I can just drive a small car through the passage and around the front yard. This is probably the first time in a long while that a car has been in the front yard.

2020 landslip

2020 was the first China Virus year and in March we started a lockdown and the only way people could visit was to walk here as part of their allowed daily exercise. So railway operations and maintenance declined severely.

On May 27th we had a landslip next to the driveway bridge. Luckily the bridge is supported by trestle bents and was unaffected. The embankment wall here had collapsed years ago and I'd patched it up using rocks and dirt back in 2016. Later patching also used tree trunk offcuts. The parlous nature of this section of the embankment was well known. I took this latest landslip as a warning that a more serious repair was necessary.

The embankments are dry stone walls (mainly basalt) and filled with clay and whatever dirt was available at the time (1960s ?). The issue with this approach is that the clay expands with water and can bulge the walls. This is more pronounced in the bridge area due to the height of the embankments here. The height and weight of the embankments means that maintenance is difficult. Also, the inward lean on the outer wall means it will probably collapse inward if the rest of the embankment is removed. This meant that removing the collapsed area for a total rebuild was not an option unless the outer wall was also brought down.

I decided to reduce the height of the embankment here to a stable level. One difficult task was removing the concrete pad (estimated 270kg) that supported the bridge before the trestle bents were installed. For safety I had to support the bridge mid span and remove the adjacent trestle bent in case the end wall of the embankment collapsed. Luckily I did manage to get this mass of concrete down to ground level.

Track alignment

The track near the driveway bridge was always a worry because it is so high and there were sharp curves before and after this bridge. Since one approach was now missing it seemed the perfect time to re-align the track and also even out the gradient in this area. When leaving the main yard the track used to drop slightly to the driveway bridge then rise up to the triple bridge. I calculated this could be changed to a constant 1 in 148 rise from the yard exit turnout to the triple bridge. This required raising the driveway bridge 76mm which was easily done.

I realised that having a curved path across the bridge would improve the curves on the approaches. The minimum radius on the bridge is defined by the allowable track offset from the longitudinal centre line. I set this to 75mm to maintain sufficient clearance from the bridge trusses. This gave me a 15699mm radius.

With this 15699mm radius on the bridge I needed a 12903mm radius on the western approach. This extended to very close to the yard exit turnout. At this stage I had the alignment decided to the centre of the bridge and work began in this area. The embankment was lowered slightly and plastic laid to reduce the water ingress to the clay filling. The track bed was then made using recycled road base. The bridge beams were rotted at each end and had to be truncated and then spliced so extensions could be installed. After adding a short extension to the bridge the track was laid up to the middle of the bridge.

The calculated radius east of the bridge was about 20m so the decsion was to start this at the centre of the bridge and this resulted in a 18083mm radius.

Bridge extension

The bridge beams are 7" by 3" hardwood and probably impossible to get now. The eastern extension for this bridge had to be 2.7m long to meet the stable portion of the embankment. I used two 3m lengths of 8" by 3" treated pine for this extension. To support footways here this extension has 3" by 1.5" channel iron. The embankment end is supported on half-stirrups.

Embankment rebuild

After installing the bridge extension over the partially dismantled embankment the area was cleared as much as could be safely done and the wall rebuilt using the stones and dirt. The top was lowered and plastic added to deflect the water and finally the track bed and track were installed.

More levelling

The gradient from the triple bridge to the crest was uneven so after purchasing another 2 tonnes of road base the track was rasied (mostly) and lowered in parts to provide a constant 1 in 92 gradient. The run from the yard to the crest is now 1 in 148 to the triple bridge, 1 in 200 across this bridge, and then 1 in 92 to the crest.