This paper describes the architecture, functionality, and field demonstration results of a newly developed dedicated short-range communication–based vehicle-to-infrastructure work zone traffic information system with vehicle-to-vehicle assistance. The new system is portable and can automatically acquire important work zone travel information such as the travel time and the starting location of congestion and then relay this information to drivers approaching the congestion site. Such information can help drivers make informed decisions on route choice, prepare for upcoming congestion, or both. The authors had designed a similar system earlier; that system had limited congestion coverage and message broadcast ranges, but the new system can achieve a much longer broadcast range (up to a few tens of kilometers) and can handle much longer congestion coverage (up to a few kilometers) by incorporating vehicle-to-infrastructure communication assisted by vehicle-to-vehicle communication. The system requires only a single roadside unit to acquire traffic data by engaging the vehicles traveling on the road whether within or outside of its direct wireless access range. From the traffic data, the system estimates important traffic parameters such as travel time and starting location of congestion and periodically broadcasts this information back to the vehicles approaching the congestion well before they enter the congested area. The results from the field demonstration show that the new system can adapt to a dynamically changing work zone traffic environment and can handle much longer congestion lengths as compared with the previous system, which used only vehicle-to-infrastructure communication without vehicle-to-vehicle assistance.