Bridge Investment Act of 20 21 This bill establishes a bridge investment program to award competitive grants to certain governmental entities for projects that improve (1) the condition of bridges; and (2) the safety, efficiency, and reliability of the movement of people and freight over bridges. Among other things, the bill requires grant awards for large projects (projects with total costs of greater than $100 million) to be at least $50 million, and for any other projects not less than $2.5 million; directs the Department of Transportation (DOT) to consider a number of factors in awarding grants, including the extent to which a project demonstrates cost savings by bundling multiple bridge projects; requires DOT to prioritize projects that are located within states for which at least two project applications were submitted in the current fiscal year and an average of two were submitted in prior fiscal years, and fewer than two grants have been awarded for projects within the state; and limits funding for projects that consist solely of culvert replacement or rehabilitation.