A systematic procedure is developed to estimate additional highway costs associated with rail branch line abandonment. The procedure is tested in an area in south-central Kansas where three Missouri Pacific (MP) branch lines were recently placed in the Interstate Commerce Commission's Category I abandonment classification. Results suggest that the procedure can be used to estimate additional damages to county, municipal or city, and state road systems resulting from branch line abandonment. Abandoning the three MP branch lines in south-central Kansas will result in an estimated additional annual truck damage to Kansas rural highways amounting to $138,274 for farm-to-elevator movements of grain. Incremental road damage cost caused by rail abandonment is estimated at $55,961 per year for intercity grain traffic. The procedure also reflects the abilities of intercity and farm-to-elevator road systems to absorb additional grain traffic resulting from branch line abandonments. An additional bushel of grain moved 1 mi by truck is estimated to cause additional damage to roads amounting to 0.90 cent for farm-to-elevator routes while costing only 0.17 cent for intercity routes. A combination of local roads, collectors, and minor arterials generally composes a farm-to-elevator route, whereas a combination of minor and major arterials and Interstates composes an intercity route. The same procedure can be used to estimate incremental road maintenance costs of rail abandonment for other types of traffic.