Track Testing

Track Checking Equipment

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To promote safety the track must be regularly checked for several parameters.

  • Standard of ballast bed - Sleepers must be well supported without voids in the ballast under the sleeper/rail junctions.
  • Sufficient and correctly placed ballast.
  • Rails must be firmly secured to the sleepers.
  • Any fastenings must be checked for condition and tightness.
  • Correct rail gauge.
  • Good line on straight and bends alike.
  • Correct superelevation on curves.
  • Wear of components, particularly railheads.
  • Drainage.

This is a formidable list, but to it must be added examination of switches, signalling equipment and the like.

When I was working with Matisa machines on-track, there were 'lengthmen', who walked their own length of track and reported back on any track faults that they couldn't repair themselves. By all accounts there are no such jobs today, and more's the pity. Experienced men such as the lengthman could catch a problem before it became dangerous or, indeed, expensive.

There is a wide variety of specialised equipment for checking track

"Small tools"

The cross-level gauge is used universally for checking track. The model shown has spring-loaded lugs that contact the inside faces of the rail heads, showing the distance between the heads. It also has a spirit level bubble to check whether the track is level and to determine the superelevation on curves.

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The curve corrector was a push-along tool used for assessing and improving curve alignment. The apparatus gives a continuous recoding of versines over a chord of 10 metres (33ft) to an accuracy of half a millimetre (it says in the manual)

 

Detail of the recording head

In use, the trolley was pushed around a curve taking a recording on a chart that could be saved as a record. Alternatively the track could be processed there and then if needed. In this case a line was drawn through the points on the chart to represent a fair curve after which the instrument was taken backwards through the curve and at each point the track could be slewed to the correct line The Corrector remained in position to check and regulate the operation, but could be instantly offtracked as it was very light. It could be folded to reduce its length for transporting.

"Telescope and Target"

 

The telescope and target could be used in several ways for checking track. The sets were made in two different heights The same telescope was used during remote operation of lifting tamping machines

"Track recording Trolley Matisa PV6 Circa 1960"

The PV6 was a self-propelled vehicle carrying equipment for measuring and recording the parameters of any track it travelled over. It could measure track under load to an accuracy of 1mm.

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View of the recording head of the PV6 recording trolley showing the pens and a chart being traced

The trolley could travel at up to 37mph, with a recording speed of 18mph.

The parameters measured were:-

  • Gauge
  • Skew
  • Cant (Superelevation)
  • Versines over a chord of 10 metres, measured for both rails
  • High and low points for each rail.

The trolley could run in either direction; the chart always ran the same way. Three scales of recording were available depending on the job in hand. The PV6 could be fitted with Ultrasonic Rail Flaw Detection Equipment to detect cracks in the rail. These are not always visible from outside the rail.

 "Electronic Track Recording Coach circa 1960"

This coach, 77ft long, could be linked up to any train and was capable of making geometric and dynamic records of track parameters under realistic loads. It weighed 60 tons and could record at speeds up to 75m.p.h In its day it was probably the height of recording technology. Is it being beaten today?