Sometimes when they dig into the ground they find something unpredictable e.g. contaminated soil which can result in a major cost blowout, a legal fight between government and contractor and then unplanned delays which further increases costs.
Sometimes when they dig into the ground they find something unpredictable e.g. contaminated soil which can result in a major cost blowout, a legal fight between government and contractor and then unplanned delays which further increases costs.