On　the　basis　of　exploring　the　significance　of　research　on　the　vehicular　operating　speeds　on　long　tangent　expressway　sections,　this　study　collected　the　continuous　and　undisturbed　operating　speed　data　of　passenger　cars　on　long　tangent　sections　by　advanced　(vehicle-based)　GPS　devices　and　analyzed　the　vehicular　operation　speeds　on　the　sampled　long　tangent　expressway　sections.　Then,　in　consideration　of　the　variations　of　vehicular　operating　speed　on　long　tangent　sections　and　drivers＇　characteristics　on　the　sections　such　as　tendency　toward　speeding,　lagging　responses,　etc,　a　model　of　continuous　vehicular　operating　speeds　on　long　tangent　sections　was　developed　in　the　form　of　a　second　order　differential　equation.　©　2010　ASCE.