This　paper　studies　commuters＇　departure　time　choice　behavior　along　a　bottleneck　constrained　highway　connecting　a　resident　area　and　a　workplace.　Commuters　are　differentiated　by　their　value　of　time,　and　the　bottleneck　capacity　is　assumed　to　follow　a　uniform　distribution　within　a　range.　The　equilibrium　properties　of　the　proposed　model　are　derived　and　individual　travel　cost　is　obtained.　It　is　found　that　at　equilibrium,　the　increase　of　capacity　variability　would　change　the　commuters＇　travel　behavior　by　increasing　the　expected　equivalent　travel　time　and　lengthening　the　peak　period.　Every　commuter　is　better　off　by　reducing　the　individual　travel　cost　if　the　stochasticity　of　the　capacity　decrease,　and　commuters　with　high　value　of　time　benefit　more　than　those　with　low　values.　Numerical　results　are　presented　to　support　analytic　findings.　©,　2014,　Science　Press.　All　right　reserved.