Pavement design is determine of the type and pavement construction thicknesse to accomodate traffic for along design life. estimation of traffic is very importance to the pavement design result. Lane with is one from several problems wich impluence to estimation of design traffic, and lane width of road in Indonesia was varies and very different with foreign. Lane width of road can affect to riding confort and for road user safety, so road user behaviour will different depend on lane width of road is used. This paper discusses correction factos to design traffic effect of lane width, especially for road with two lanes two way. Activities undetaken are included literature reiview, canalization survey or vehicle wheel path on several road links with two way with different lane width and data analysis. Based on the analyisis result, found that for road with two lane two way and lane width is less than minimum lane width of 3.5 metres, so wheel path of vehicle wich use wheel path on design lan eis more increase. Thus for estimation of traffic in design lane is required correction factor. especially for roads with fairly heavy volume, regional corners, climbs or descendants , then the amount of lane width correction factor (fw) should be based on the survey results directly in the field.