As　China　feverishly　builds　one　of　the　largest　freeway　systems　in　the　world　to　meet　its　ever-increasing　demand　for　highway　transportation-stimulated　by　the　unprecedented　economic　boom-traffic　safety　has　become　a　serious　concern.　The　problem　of　more　than　100,000　annual　traffic　fatalities　is　threatening　the　country＇s　sustainable　economic　development.　The　significant　differences　in　road　user　behavior,　level　of　motorization,　traffic　enforcement　practice,　roadside　design　criteria,　and　economic　development　stage　make　the　characteristics　of　traffic　crashes　in　China　somewhat　different　from　those　in　developed　countries.　To　reduce　traffic　crashes　it　is　important　to　investigate　what,　when,　how,　and　why　those　crashes　occurred.　This　paper　introduces　a　highway　safety　project　conducted　on　Jingjintang　Expressway,　one　of　the　first　freeways　built　in　China.　Results　of　the　study　show　that,　among　other　factors,　the　speed　differential　between　cars　and　large　vehicles　is　a　main　cause　of　high　crash　fatalities,　particularly　for　rear-end　collisions.　The　lack　of　real-time　enforcement,　problematic　driver　behavior,　and　substandard　roadside　design,　as　well　as　overloaded　trucks　all　contribute　heavily　to　traffic　crashes　on　China＇s　freeways.