For about 12 months now I've been dabbling in O gauge. I've built a few locos and wagons so it's time to build a railway for them.   Scene:   Part of the internal railway system of a tar distillers/chemical works, somewhere in the West Riding, mid 1960s. A BR connection and more of the works is off-scene.   Traffic/Rolling stock:   Goods in - unspecified goods in covered vans, tar from NCB coke ovens in rectangular tanks.   Goods out - chemicals to industrial users in cylindrical tanks