This bill proposes an amendment to section 133 of title 23, United States Code, to expand the scope of projects eligible for funding under the surface transportation block grant program. Its primary provision is to specifically include the construction of roundabouts as an eligible activity. By designating roundabouts as eligible projects, the legislation intends to enable states and local governments to utilize federal surface transportation block grant funds for their development. This initiative aims to encourage the implementation of roundabouts, which are often recognized for their potential to improve traffic flow and enhance safety at intersections.