Concrete Re-Sleepering on the Main West line at Gemalla

The Challenge:

Located along the Main West line at Gemalla, between Lithgow and Bathurst in NSW, the rail project being conducted by John Holland required the surveying expertise of Hanlons.

Through survey and track design, the longevity of this crucial section of transport infrastructure would be extended. Hanlons were chosen for our reliability, deep knowledge of rail and sound performance on similar projects conducted with the client.

The Solution:

Through a combination of experienced and well trained surveyors and designers, efficient surveying techniques and modern equipment, sufficient surveying resources were used to execute the project.

Beginning with pre-planning to coordinate detail survey teams to match rail traffic windows and ensure the design delivery permitted sufficient time for review, five surveyors and two drafters from Hanlons were assigned the project. There was extensive liaison between the team and the CRN project managers regarding timelines. 

Various tools and instruments were used to conduct work on the project. Leica survey equipment was used to collect initial site data and set out the rail works, and again to survey the final built railway for the purpose of comparison to the design. CompNet statistical survey adjustment software enabled the analysis of blocks of observation data sets to ensure survey stations had accurate coordinates, right down to the millimetre. The importance of accuracy comes down to a track needing to be built to +/- 5mm, requiring the point from which the track is laid in to have a more accurate coordinate, guaranteeing that 5mm can be achieved. 

Downloading raw survey data, i.e the location of the existing track, ballast, signals and level crossings, along with the generation of the final rail design was conducted using Magnet survey and design software. Knowledge of existing features and their locations allows them to be avoided or incorporated into the design. For example, concrete sleepers are thicker than most existing steel sleepers by approximately 100mm, requiring considerations such as lifting the track, causing it to “dip”, or dropping the track, removing critical ballast to stop movement in the sleepers, highlighting the importance of survey and design. Design is presented using Autocad technology, showing the design intent in a form that can be understood by all stakeholders. In the case of this project with John Holland, the review team, construction team, maintenance team and asset owner were presented with the design. 

Hanlons aim to keep the big yellow machines moving, so more time spent checking levels during construction means less available time to do their thing. It’s important as surveyors to make the client’s life as easy as possible by providing continuous innovation and constant communication.