  Reducing the response time of Emergency Vehicles (EVs) has an undoubted
advantage in saving life and property. Implementing pre-emption can aid in
achieving it. EVs get unobstructed movement via pre-emption, usually by
altering traffic signals and giving a green wave throughout the route. This
approach of absolute pre-emption effects adversely on regular traffic by
imposing unnecessary waiting. In this paper, we propose a novel emergency
vehicle pre-emption (EVP) algorithm implemented in the Vehicular Ad-hoc Network
(VANET) that can reduce the imposed undesirable waiting time, but still
ascertains EVs meet target response time. We introduce mixed-criticality
real-time system scheduling concept where different level of emergencies is
mapped with different criticality levels and assign certain success assurance
level to respective criticality. We implemented the EVP algorithm for an
arterial traffic network and leveraged the use of valuable information that
gets transmitted via VANET to make critical decisions. The proposed algorithm
can significantly reduce the average waiting time of regular traffic. It also
ascertains all EVs with different level of criticality meet target response
time respective to their assurance level.
