REGISTER

David Scott BSc. Elec Eng., C.Eng., M.I.E.T., F.I.R.S.E.

Senior Signal Engineer – Lead, Calibre Rail

The rapid growth in the Western Australian iron ore industry during the past decade has facilitated rail expansion programs that have schedules of implementation beyond 2015.
Preliminary engineering studies have been completed and procurement contracts initiated for long lead signalling materials effectively freezing the design model.

The main line signalling design concept has been structured around the provision of standardised distributed interlockings controlling turnouts within the limitation of its solar based power supply and acceptable voltage drop along point machine or coded track cables. Adjacent interlockings are vitally connected by track code or failsafe data communications using a lineside transmission medium.

A similar approach has been applied to yards that have equally expanded and justification exists to motorising turnouts resulting in the traditional reflectorised Mechanical Point Indicator (MPI) being replaced by Light Emitting Diode (LED) units with the objective of improving approach visibility and defining Limit of Authority (LOA) or track clearance positions.

The temporary disruption to iron ore production due to the 2008/09 economy downturn has delayed expansion project activities and provided the opportunity to assess the performance of completed portions.

Unfortunately the application of LED technology to yard turnouts has not had any significant impact to reducing yard LOA incidents, with one upgraded yard recording several LOA breaches in the last year.

This paper tracks the changes and developments to yard point indicators to provide an understanding of the issues that complicate their application and draws an observation that the cut and paste design approach used to signal large expansion schemes may need to be reviewed from a different perspective otherwise their limitations may contribute to additional operating risks during their 10 year service life.