Daring to Loosen the Shackles of Traffic Control: A Link-Centric Manifesto

Traffic signal control has been done, for well over a century, with red and green signals and intersection
queuing, so as to avoid collisions among vehicles in crossing-conflict movements. Signal cycles of more than a
minute of typical length were required due to startup and clearance lost times, even when queuing delays in the
absence of lost times would essentially be (linearly) less with lower cycle lengths. Can new technologies help us
design signal control that does not force vehicles to stop but lets them go through conflicting streams without
accidents? In fact, should we even start with the presumption that crossing movements involve more safety risks
than car-following? Preliminary analysis with time-space conflict regions show that human drivers face significant
accident risks in no-conflict car-following but are able to avoid it all the time. Can we then imagine signal control
that allows designed and timed movement across conflicting streams, perhaps with technology assistance, thus
essentially removing stopping and signal cycling at nodes? In such a scenario, the control can be in the form of
timed flashing greens on approach links rather than at nodes. Dramatically more efficient traffic control designs now
become possible and are being developed at UCI. With the help of simulated results, this talk will raise the
possibilities of a new paradigm in traffic control that is link-based and not at the network nodes.

Dr. R. Jayakrishnan has been in the faculty of Civil and Environmental Engineering at the University of California at
Irvine since 1991, after receiving his BTech from the Indian Institute of Technology, Madras in 1985 and his
doctorate from the University of Texas at Austin. His research interests are in a variety of topics such as Traffic Flow
Theory and Simulation, Transportation Systems Analysis, Network Modelling, Decision Theory, Intelligent
Transportation Systems and Public Transit Design. He has been in the editorial committees of journals such as the
ASCE Journal of Transportation Engineering and Transportation Research Part-C and has served in several
professional committees and academic panels of the Federal Highway Administration, National Science Foundation,
and the Transportation Research Board. 25 PhD students have graduated under his advice, with nearly half of them
in faculty positions around the world. He has about 150 refereed publications to his credit and he is currently the
Director of the interdisciplinary Transportation Science Program at UC Irvine