Optimal time for contractors to enter infrastructure projects

involvement (ECI) is a project delivery method where the goal is to include construction knowledge into the design phase. This isdone by procuring the contractor during the design phase of a project. There are different approaches to which time the contractoris introduced. This research paper aims to investigate the optimal time for contractors to enter infrastructure projects. In order todo this, an empirical study was conducted, where interviews were held with nine representatives from an ongoing ECI project inSweden. The studied project was procured by the Swedish Transport Administration, and the contractor entered the project at thebeginning of the design phase, before a land acquisition plan had been developed. This is the first time in Sweden that a contractorhas been procured this early in a road project. The findings from the interviews show that responsibility, understanding, innovation,risk management, relationship-building and implementation are the aspects that have been affected due to ECI. By analyzing anddiscussing the results, it was concluded that involving the contractor as early as in the studied case has been beneficial, and thatinvolving the contractor as early as possible in infrastructure project is favorable