The Tribal Roads Improvement Act removes federal restrictions that prevent tribal governments from using transportation program funding for road grading on tribal lands. Currently, approximately 160,000 miles of roads on or providing access to tribal lands exist, with about 65 percent in poor or failing condition, and federal funding covers less than 35 percent of identified maintenance needs. The bill allows tribes to allocate more of their transportation program funds toward grading work, which the legislation argues will improve access to healthcare, education, employment, and emergency services while supporting tribal economic development and self-determination. The Secretary of the Interior must conduct a study within three years to measure the impact of this change, examining factors like road condition improvements, miles graded, tribal employment generated, and effects on emergency response times and economic development. Within two years of completing the study, the Secretary must report findings and recommendations to Congress regarding ongoing tribal road grading needs.