Construction Simulation Model Tackling Increased Constraints on a Complex Earthmoving Project

Overview:




Consolidated Contractors Company (CCC) is the largest construction company in the Middle East and ranks #18 internationally. CCC has offices and projects in over 40 countries, and a workforce of more than 130,000 employees. Its portfolio includes oil and gas plants, refineries and petrochemical facilities, pipelines, power and desalination plants, light industries, water and sewage treatment plants, airports and seaports, heavy civil works, dams, reservoirs and distribution systems, road networks and skyscrapers.


CCT International (CCT) is the primary technology provider for CCC since 1998. CCT also develops and markets solutions for the construction industry with clients all over the world. CCT products include 3D BIM/project control environments, document and content management solutions, mobile construction management systems, asset management and fleet management systems, QA/QC systems, and construction process simulation & optimization tools. CCT has offices in Beirut, Dubai, Cairo, Athens, and Cyprus with a headcount of around 65+ engineers, software developers, and industry experts.


Problem:




Just after contract signature of a site preparation project (earthmoving scope of approximately four million cubic meters), the client and local authorities placed new, more restrictive constraints on the operation. These constraints included:

  • Trucks were now allowed to run at a maximum of 10kph within the construction project site instead of the original 20kph.
  • Trucks from/to dump location were instructed to follow a specific route full of traffic lights, intersections, roundabouts and security gates. Accordingly, the original assumption of an average of 40kmph truck speed on route from and to dump site could not be maintained.
  • Truck sizes/loads were brought down from a maximum allowable of 32m3 to 15m3.  
  • Number of truck trips restricted to a maximum of 100/hr.
  • Only one of the original four site access points was granted after contract signature thus restricting all traffic on site to one gate. 
  • Only one work shift (10hrs/day) was allowed for dumping at the dump site in contrast to the original two-shift (20hrs/day) schedule.

Construction Simulation Modeling

The newly placed constraints essentially meant that the project schedule will be severely impacted and with it the total cost to complete. The number and complexity of the constraints made it quite difficult to evaluate manually the impact of the constraints on time to complete and equipment requirements. As a result of the newly added complexity the simulation team was asked to help in quantifying the impact of the new constraints and substantiating a claim by CCC for an extension of time.


Construction Simulation Model

Truck Route Model Outputs Showing Route Visualization and Average Speeds

Solution:




CCC already had a well-established AnyLogic-based earthworks simulator used to forecast equipment and time requirements for earthworks operations. Using that simulator requires multiple parameter inputs including the assumed average speed the trucks will travel on their haul routes and back. With the new truck route imposed on the project, it was very difficult to estimate manually the average speed the trucks would run at.


As such, a simulation model was built in AnyLogic to mimic the trucks traversing the route segments while loaded and empty. In the construction simulation model, each route segment was modeled with a stochastic distribution for the total time to traverse the segment. Then the trucks were made to run 10,000 times each way in the simulator to arrive at an average speed for each route and loaded/empty combination. AnyLogic was specifically selected because it allowed CCT to:

  • Very quickly build a model of the route and its segments 
  • Add a map of the routes and superimpose an animation of the trucks traversing the routes to make it easier to explain the work visually to stakeholders.

The average speeds deduced from the truck route simulator were then fed into the earthworks construction simulation model along with the remainder of the new constraints. These included:


  • Truckload sizes and number of work shifts (working hours) per day to produce multiple scenarios showing the original forecast time and equipment requirements to complete the operations. 
  • The current forecast time and equipment requirements to complete the operations (impact quantification in time and resource requirements). 
  • Proposed mitigation scenario.

Outcome:




The results of the two-step process of using the truck route simulator to summarize the route and then feeding it into the earthworks simulator enabled CCT to quantify very quickly the impact of the new more restrictive constraints and to build mitigation scenarios to aid in the claim for extension of time.


Based on the construction simulation model results, the client agreed to extend the total duration of the earthworks operation by an additional 50% on top of the original schedule duration and to allow two work shifts per day. This essentially saved the project an estimated additional total cost equivalent to 18% of the original total contract value.

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