Emerging in-car communication technologies continually offer new communication capabilities between vehicles and infrastructure that, together with more accurate positioning systems, can be used to improve the use of current infrastructure. The aim of this paper is to present a novel merging assistant strategy that exploits cooperative systems to reduce congestion at motorway junctions. This new system, called Cooperative Merging Assistant, groups main carriageway vehicles together and collects the intervehicle spaces into gaps that are usable by merging traffic. These gaps will facilitate the coordinated entry of platoons of vehicles released by an on-ramp traffic signal. The performance of this new system is evaluated using microscopic simulation. Results show the reduction of late-merging vehicles, decrease in congestion and increase of merging capacity. This study shows how the use of cooperative systems can improve the merging maneuver and thus lead to a reduction of congestion on motorways. © 2000-2011 IEEE.