  Vehicle platooning is an automated driving technology that enables a group of
vehicles to travel very closely together as a single unit to improve fuel
efficiency and driver safety and reduces CO2 emission. The significant benefits
of platooning attracted huge interests from academia and industry, especially
from logistics companies for utilizing platoons of "long-body" trailer trucks
because of the huge cost savings. In this paper, we demonstrate that existing
DSRC-based platooning solutions, however, fail to support formation of such
"long" platoons consisting of typical trailer trucks because of the limited
communication range of DSRC. To address this problem, we propose L-Platooning,
the first platooning protocol that enables seamless, reliable, and rapid
formation of a long platoon. We introduce a novel concept called Virtual Leader
that refers to a vehicle that acts like a platoon leader to extend the coverage
of the original platoon leader. A virtual leader election algorithm is
developed to effectively designate a virtual leader based on the novel metric
called the Virtual Leader Quality Index (VLQI) which quantifies the
effectiveness of a vehicle serving as a platoon leader. We also develop
mechanisms for L-Platooning to support the vehicle join and leave maneuvers
specifically for a long platoon. Through extensive simulations using the
combination of Veins (Plexe) and SUMO, we demonstrate that L-Platooning enables
long-body trailer trucks to form a long platoon effectively and maintain the
desired inter-vehicle distance precisely. We also show that L-Platooning
handles seamlessly the vehicle join and leave maneuvers for a long platoon.
