What is the ruling on the owner of a construction company paying bribes to government engineers to facilitate his work, and is the money earned from these dealings unlawful?

If the company adheres to specifications and does not violate them, and pays money to corrupt engineers to obtain its rights and دفع الظلم (ward off injustice), then there is no harm in that, and the company's money is lawful. This is because it is not among the forbidden bribes that invalidate a right or uphold a falsehood; the sin falls upon the engineers. However, if the company compromises the quality of work and pays engineers to cover up its defects, then this is a forbidden bribe, and all profits the company earns from such activities are unlawful.