with a statistical basis
This project concerns the study of several transport routes (roadways and railways) linking different key-points part of the industrial unit which Portucel is implementing in the provinces of Zambézia and Manica (Mozambique).
The main goal of the project meant to grant the client thorough cost estimation for each of the several sceneries under study, including the costs associated to the construction itself (CAPEX) and to the operation for a 40-year period (OPEX).
The financial estimation of the different sceneries was supported by a risk assessment study that incorporated statistical methods for variable analysis (costs and quantities). In the course of the project, GEG has implemented «Value Engineering» methodology in order to get the best results and reduce, at the same time, the uncertainty associated with the solutions under study.
Two different studies have been produced: one in the provinces of Manica and Sofala, and another one in the province of Zambézia. For each one of the studies, different options for the accesses have been studied, either building or rehabilitating railway lines and roads, linking the forest areas (raw material) to the industrial unit (cellulose pulp factory) and to the area of the seaport.
with a statistical basis
~ 100 km
~ 1500 km
The first stage consisted in gathering and analyzing the available information, including the data supplied by the customer, geological and hydrogeological studies, topography and other data resulting from the consult of the appropriately available bibliography.
In this stage, where the main features of roads, railway lines and other project constraints are defined, the Customer’s goals should be well addressed, serving as a basis for the whole project.
In order to prepare the visit and inspection to the site, the main corridors and key points of each scenario have been specified, defining the existing roads and railway lines to be inspected, and preparing at the same time the inspection application forms to speed up the gathering of information on the scene.
Road and railway inspections were undertaken in the course of the visit, including inspections to some specific special structures and drainage works, in each one of the targeted scenarios. From the inspection of a total of about 1500 km of communication routes, the highlights go the inspection of a 100 km railway line in the provinces of Manica and Sofala (Machipanda Line) and the inspection of 111 special engineering structures – bridges and viaducts – in the province of Zambézia.
In this stage, it was undertaken a Preliminary design for each studied scenario encompassing layout, pavement, earthwork, drainage new special structures and the rehabilitation of the existing roads and railway lines. There were also outlined the settings to be considered in the maintenance operations throughout a 40-year life cycle. Using this information there was produced the first estimation of construction costs (CAPEX) and the maintenance costs (OPEX).
In order to define the construction solutions to be implemented, the unit costs to be used and their variability, it was used the Delphi Methodology. This one characterizes itself as a scientific methodology, suitable to the gathering of information, collected from multiple experts, in a particular operation area. At this stage, the probabilities of the events related to quantities and cost variables were established.
All the settings were then combined for each scenario, in order to determine the associated costs and risks with the due changes, correlations and risks.
The quantities and risks template that was employed was based on a stochastic simulation, using the Monte Carlo Method. In the Monte Carlo simulation, every input variable has an associated function of probability distribution. In this simulation, the input distributions are randomly sampled, repeating the process a several number of times in order to obtain an effective distribution.
The Monte Carlo Method generates probabilistic and graphic results, the production of sensitivity analyses and the possibility of creating different scenarios. It is, therefore, the most appropriate method of including uncertainty in the variables of one given study, providing at the same time an effective support for the customer’s decision making.
The conclusion of the studies meant the submission of the projects, together with the correspondent detailed report with the information related to the used methods, the total costs of each scenario, presented as distribution functions, the risk analysis of the undertaken studies and suggestions for future study developments.