Trimble Alignment Planning: Bauhina Mine Regional Rail Project

"The project planners demonstrated that there is significant benefit to applying the Trimble Alignment Planning system to mine haul/access roads, and have stated that the earlier Trimble Alignment Planning is applied, the greater the benefits."
MIM Holdings

MIM Holdings (now Xstrata PLC) commissioned the Trimble Alignment Planning system for application by their appointed consultant, Parsons Brinkerhoff, on a 92km section of the Bauhinia Regional Mine Rail Project.The major objective of MIM was to find the most cost effective rail alignment, which ensured the minimum operating costs over the 20 year mine life cycle, whilst limiting the community, environmental, and heritage impact.

Considerable alignment work had been undertaken prior to the application of the Trimble Alignment Planning system. The original CAD derived alignment did not consistently meet the maximum defined grade, and multiple crossings were below the defined minimum clearance. Using the Trimble Alignment Planning system, the project planners were able to define the corridor, zones and rules to deliver an alignment construction cost reduction despite the extremely restricted corridor and rolling terrain through much of the study area.

Project specific benefits included:

• Improvement on the alignment quality, both horizontally and vertically;
• Met many of the crossing constraints defined by the designers that were not met by the CAD derived alignment;
• Allowed the planners to deliver substantial comparative alignment construction cost savings:
• 23% when Trimble Alignment Planning applied to meet similar constraints as CAD alignment;
• 11.7% when the additional constraints and features were included.

The project commenced with conversion of the digital terrain model into Trimble Alignment Planning format. The project planners then defined the design standards, constraints, features (with associated crossing rules), geology and unit costs.

The corridor width and alignment options were tightly constrained by land acquisition issues and a corridor boundary was created by MIM to limit the scope of investigation.

The anticipated dump and borrow pits were replicated by first determining a preferred alignment and then optimizing within four sections. Note: the capability to define borrow pits, dump sites and barriers to earthworks haulage has now been integrated into the system.

The Trimble Alignment Planning System identified and costed approximately 12 million alignment options with each run and delivered a range of low-cost alignments to the project planners for review within one working day.

Figure 2 shows a profile comparison of the CAD alignment, highlighting the crossing, grade, horizontal curve and vertical curve constraints violated, and the Trimble Alignment Planning derived alignment, which had no violations.

To enable full project comparison, the costs for the four sections were combined for both the CAD derived alignments and the Trimble Alignment Planning derived ones. On a direct comparison with CAD using the same constraints, the project team achieved an alignment construction cost savings of 23% with the Trimble Alignment Planning system.

When the additional constraints that the project needed to comply with were added, the planners were able to deliver improved quality alignments that met all of the constraints violated by the CAD alignment, and still delivered an alignment construction cost saving of up to $14.13m (or 11.7%). The study also demonstrated that Trimble Alignment Planning has the capability to rapidly generate alignments for each scenario defined, enabling the planner to:

• Identify low-cost alignments that meet the defined constraints;
• Consider changes to constraints, engineering specifications or start points in a fraction of the time required by the conventional approach;
• Demonstrate respect for the community and the environment;
• Evaluate (audit) alignments derived using the conventional planning approach;
• Carry out sensitivity analysis to determine the alignment and cost impacts of changes to design standards and costs, and the addition/amendment of constraints; and
• Produce reports and displays that can support the consultation process.

This document consists of extracts from "Bauhinia Mine Regional Rail Project: Applying the Trimble Alignment Planning system on mine rail haulage infrastructure" paper.