Most drivers have come to accept the regular and frequent maintenance and construction activity on motorways as a necessary nuisance, as the strain on this type of infrastructure is considerable, and damage frequent. However, aside of being just inconvenient, it has been repeatedly suggested that such motorway work zones might be associated with an increased crash risk. One of the factors that has the potential to contribute to work zone crashes is lane width. Goal of the present study was to investigate the effect of left lane width on driver behaviour in motorway work zones. Seventy two participants in two age groups (20-45 and 55-80 years) took part in a driving simulator experiment, in which they drove on the motorway and passed through multiple work zones with a left lane width of either 2.50 m, 2.75 m or 3.00 m. Once participants entered the work zone, they approached two platoons of vehicles, which they were allowed to overtake if they felt it was necessary and possible. Our results show that left lane width did not influence the participants’ willingness to overtake. At the same time, their reported ratings of stress and their assessment of work zone features clearly indicate that they perceived the differences in lane width. A narrower lane width was accompanied by a lower mean speed when travelling on the left lane. In addition, the recorded values indicate that the narrower the left lane, the further right of that lane’s centre the participants travelled (often crossing into the adjacent right lane). The findings suggest that differences in lane width are perceived by drivers, that they increase the drivers perceived stress level, and that some behavioural adaptation occurs. However, the fact that driver still opted to overtake most of the time is somewhat worrisome.