This　paper　deals　with　the　dynamic　routing　problem　of　traffic　flow　through　transportation　networks　by　using　variable　message　signs.　Comparing　with　some　previous　researches,　the　paper　considers　the　norm-bounded　exogenous　disturbance　in　the　traffic　model.　By　applying　the　MINIMAX　control　approach,　it　is　shown　that　the　resulting　control　law　is　of　the　bang-bang　type.　The　genetic　optimization　method　is　used　to　calculate　the　control　law.　Finally,　the　contrast　of　the　efficiency　between　MINIMAX　routing　control　and　optimal　routing　control　is　made,　and　it　is　shown　that　the　MINIMAX　robust　control　approach　is　preponderant.　©　2003　IEEE.