Various road traffic signs are placed on the shoulder to inform drivers of the work situation ahead, speed limits, and lane changes in highway work zones. In this study, we analyze the effectiveness of a portable lane-change assistance system (PLCS) that can replace existing traffic signs from the perspectives of driver visibility and lane-change behavior. The existing highway work zone traffic management guidelines were regarded as a scenario without PLCS, and the case of replacing the existing traffic signs proposed by the manual with PLCS was set as a scenario with PLCS. For each analysis scenario, we analyzed the change in subjective awareness of traffic signs, perception accuracy of PLCS, advance lane-change rate, and lane-change location. The subjective perception analysis showed that the subjective perception change rate increased by 13.85% for two-lane highways and 5.29% for three-lane highways when PLCS was applied compared to that without PLCS. Regarding PLCS perception accuracy, all drivers correctly recognized the lane closure information for the two-lane case. Two PLCS are used in the three-lane case to provide lane-closure information. Regarding the first PLCS, all drivers correctly recognized lane closure information for the first lane sign, and 31 drivers correctly recognized lane closure information for the second and third lane signs. Regarding the second PLCS, all drivers correctly recognized lane closure information for the first and third lane signs, and 30 drivers correctly recognized lane closure information for the second lane sign in the second PLCS. Analysis of lane-change behavior showed that the proportion of advance lane changes increased by 31.25% in the two-lane case and 59.38% in the three-lane case with PLCS compared to that without PLCS. Additionally, lane-change locations where drivers performed lane changes from the starting point of the work zone area were analyzed. Drivers changed lanes at 653.68 m without PLCS and at 919.66 m with PLCS resulting in a 265.98 m increase in lane change location for the two-lane case. The drivers changed lanes twice in the three-lane scenario. Drivers changed lanes at 1014.41 m and 743.64 m without PLCS and at 1137.05 m and 868.24 m with PLCS, resulting in a 122.64 m and 124.60 m increase in the lane change location for the three-lane case. The proposed PLCS demonstrated a greater recognition capability than existing traffic signs and was effectively encouraged. This can be useful for replacing existing traffic signs in highway work zones.