An Elevated Line -
Track deck straight sections were up to 8 ft. long supported by 2" by 1" underframes (j). Joins in the supporting frame were sited as far as possible from any join in the track deck - 3ft. to 4ft. away where possible.
If left with just longitudinal subframes and no lateral cross bracing the straight track deck sections would have been prone to warping. A 2" by 1" cross piece fitted between the supporting frames would have been only 3" long and liable to split. Diagram 3 shows how I dealt with this potential weakness.
I extended the width of the track deck (k) to accommodate much longer cross pieces giving more effective bracing against warping. The result above track deck level was to provide an accessories bay (l) for trackside items such as huts and signs. These bays are finished off by fixing ballast retaining walls around them.
Another advantage of an elevated line is that it is relatively easy to make changes later. The side walls can be prized away with a chisel to make way for work to extend the width of the track deck or to add new decking for a junction. This enabled me to start with a simple but viable continuous run within my budget and then extend the line in stages. However, being constructed of timber, it will require annual inspection and maintenance work.
|The diagram and text on this page are copyright (c) Paul Backhouse 1999 and may not be reproduced or distributed without the owner's permission.|