Statistical　data　shows　that　single-vehicle　crashes　account　for　half　of　all　traffic　crashes　on　expressways　in　China,　and　previous　research　has　indicated　that　main　contributing　factors　were　related　to　whether　and　how　the　inside　shoulder　was　paved.　The　inside　shoulder　provides　space　for　drivers　to　make　evasive　maneuvers　and　accommodate　driver　errors.　However,　lower-cost　construction　solutions　in　China　have　resulted　in　the　design　of　numerous　urban　expressway　segments　that　lack　inside　shoulders.　This　paper　has　two　objectives.　The　first　is　to　reveal　the　safety　impacts　of　inside　shoulders　on　urban　expressways　by　driving　simulator　experiment.　The　second　objective　is　to　propose　optimal　range　and　recommended　value　of　inside　shoulder　width　for　designing　inside　shoulders　of　urban　expressways.　The　empirical　data,　including　subjects＇　eye　movement　data,　heart　rate　(HR)　and　the　lateral　position　of　vehicles,　were　collected　in　a　driving　simulator.　The　data　were　analyzed　to　evaluate　the　safety　impacts　of　the　inside　shoulder.　The　results　have　revealed　that　the　inside　shoulder　has　an　impact　on　drivers＇　visual　perception,　behaviors,　and　psychology;　in　particular,　it　has　a　significant　effect　on　vehicle　operations.　In　addition,　this　paper　recommends　the　desired　and　optimal　inside　shoulder　widths　for　eight-lane,　two-way　divided　expressways.　(C)　2014　Elsevier　Ltd.　All　rights　reserved.