**3. Merging behavior at on-ramps and off-ramps for CAVs**

In transportation networks, overall highway system efficiency can be severely reduced due to delays caused at on-ramps and off-ramps. If the merge process is incorrectly handled, merging lanes can have an overflow effect which causes the entire highway to become congested. This effect is caused by slower moving vehicles facing congestion in outer lanes near the merge junction deciding to switch into inner lanes in order to move faster. Therefore, even vehicles in the inner high speed lanes have to slow down. Overtime with continuing merge lane congestion, the entire freeway can become blocked.

In fact, in human-driven vehicles, this issue is further compounded due to the lack of cooperation and limited visibility for decision making. However, the introduction of CAVs has led to a lot more information becoming available for improving this overall merging process. In addition to the improved local sensing on-board modern CAVs such as 360<sup>∘</sup> radar and vision based sensors, most of the increased information comes from improvements in Vehicle to Vehicle (V2V) and Vehicle to Infrastructure (V2I) communication methods. These communication protocols enable individual vehicles to broadcast their intent and status, receive command velocities to enable optimal flow and also collaborate with each other to self-organize in such a way that freeway traffic flow is optimized.

Effectively managing the highway merge problem has multiple benefits, both to the end users and the entire transportation system as well. Reduced time in traffic at merge junctions means that overall throughput of the highway is increased, individual waiting time is reduced and the wastage of fuel (energy) in idling vehicles stuck in traffic is also reduced. Therefore, it is evident that improvements to intelligent highways will have an impact on the economy as well as helping combat environmental issues caused by excessive fuel consumption.
