In　this　study,　an　experimentally　validated　spatial　analysis　method　for　the　vehicle-bridge　interaction　system　was　modified　to　include　the　features　of　vehicle　braking　and　accelerating.　The　effect　of　braking　or　accelerating　was　considered　as　external　force　acting　on　the　vehicular　center　of　gravity　and　was　quasi-statically　distributed　to　every　tandem,　for　which　the　formulae　of　load　redistribution　were　derived.　The　effect　of　centrifugal　force　was　also　incorporated　in　the　model.　Based　on　the　modified　spatial　analysis　method,　the　dynamic　responses　of　a　three-span　continuous　concrete　box　girder　bridge　due　to　vehicle　braking　and　accelerating　were　studied.　Impact　factors,　including　deflection,　bending　moment,　torsional　moment　and　shear　force,　were　examined.　The　results　show　that　vehicle　braking　has　considerable　effect　on　dynamic　responses　and　the　impact　factors　are　related　to　braking　rise　time　and　braking　position,　but　cases　of　vehicle　braking　do　not　always　cause　larger　effects.　While　the　increase　in　initial　speed　can　produce　higher　maximum　dynamic　responses　and　corresponding　impact　factors,　the　dynamic　responses　in　the　first　span　of　a　multi-span　bridge　are　smaller　than　those　in　other　spans　due　to　vehicle　accelerating.