Mass haul movement planning for large-scale infrastructure projects
Challenge
Mass haul is the process of transporting material from where it has been cut to where it will be needed or disposed of for construction projects. The aim of mass haul movement planning is to minimise resources usage by redistributing earthworks materials in an efficient manner. Material is excavated from the existing terrain at cut locations and then used to create fill sections. Factors such as material grade and construction schedules must be considered when planning earthwork movements.
For HS2 Phase 2B, this was being undertaken on a nationwide scale, hence the need to automate and expedite the planning process. The existing process was completed by hand and took several weeks to manually complete. The costs associated with planning, excavating, processing, transporting, purchasing and disposing of materials needed to be minimised.
Solution
We created a tool that processes construction schedules to build a mathematical model that then uses mixed integer linear programming techniques to optimise the model. The model considers the following factors:
- Material volume
- Material grades
- Time constraints
- Transportation
- Stockpiling
The weightings of the model can also be adjusted to reflect the different types of scenarios that could happen during earthworks. This enables planners to quickly gain deeper understanding of the impact of prioritising different design goals and the knock-on effects of different decisions.
The tool produces a series of outputs including detailed schedule of hauls, collated schedule of hauls, traffic reporting, chainage diagram and a stockpile occupancy plot, providing further information for better decision making.
Impact
The tool reduced the time taken to produce a viable plan from several weeks to under an hour. This is a significant acceleration of the design process which enables rapid iteration of different designs, leading to improved plans. It also removed the vast majority of manual work, reducing the likelihood of errors in plans. Given the magnitude of decisions this process resulted in, such as adding new motorway junctions or laying new railway lines, having the ability to consider different possibilities was critical for determining the best plan. Furthermore, this process had to be executed several times sequentially, therefore the overall time saving within this project from this innovation was of the order of years.
