The New Zealand Railways Magazine, Volume 12, Issue 2 (May 1, 1937)
Improving the Permanent Way
Improving the Permanent Way.
The high-speed services in operation, and contemplated, at Home, make big demands upon permanent way and signalling. The majority of our trunk routes were constructed three-quarters of a century or so ago, when high speeds such as we now know them were unknown. Thus, one big task to be tackled has been the reduction of steep grades and the easing of curves. For main-line use, the four group lines employ 95 lb. British standard bullhead rails in 60 feet lengths, these resting on cast-iron chairs each weighing 46 lbs., with 24 sleepers to each rail length. On sharp curves additional sleepers are provided. On the Great Western, a through bolt is utilised for securing the chairs to the sleepers. On the other three groups, three screws are employed. In recent times, a limited mileage of track has been laid with 100 lb. rails, and steel sleepers also have been introduced here and there. The difficulty with these, however, is that they interfere with track-circuiting. Considering the age of most Home main-lines, and the difficulties to be faced in the way of overhead bridges with tight clearances, congested city tracks, and so on, it is really remarkable how well permanent-way engineers have met the new demands made by high-speed running.