Baulk road

Baulk road is the name given to a type of railway track or 'rail road' that is formed using rails carried on continuous timber bearings, as opposed to the more familiar 'cross-sleeper' track that uses closely spaced sleepers or ties to give intermittent support to stronger rails.

[2] Early locomotive-powered railways had used short cast iron rails carried on stone blocks.

These rails were brittle and broke easily, and they gave a rough ride due to the difficulty of maintaining a smooth line between the blocks or sleepers.

[2] The longitudinal baulks, and therefore the rails, were kept to gauge by 'transoms' – transverse timber spacers – and iron tie-bars.

It was packed so firmly, in fact, that the track was forced upwards between the piles and thus gave an undulating ride, just the thing that Brunel had tried to address by using continuous bearings and firm packing; cutting the piles away from the transoms solved the problem.

Converting broad gauge baulk road to standard was done by cutting the transoms and slewing the longitudinal and its rail to its new position.

For baulk road this meant laying an additional longitudinal between the existing two (one rail was common to both gauges), but this significantly increased the cost and complexity of the track compared to cross-sleepers.

In its original form it was only about 4 inches (102 mm) deep and was used on baulk road interchangeably with bridge rail.

[2] Baulk road was used by John Coode for a number of 7 ft (2,134 mm) railways that he built as part of large construction schemes for harbour breakwaters at places such as Portland and Table Bay.

The design varies considerably, but in many cases longitudinal timbers are supported directly on the cross-girders, with transoms and tiebars to retain the gauge, and modern rails and base-plates or chairs laid on top.