Abstract:In urban transportation, scheduling algorithms in traffic signal control (TSC) are important for achieving high throughput and low latency traffic flow, lowering accidents, and reducing emissions. As new scheduling algorithms are being developed particularly to leverage and accommodate connected and autonomous vehicles, there is increased potential for cyber-attacks on TSC that can undermine the benefits of new algorithms. Attackers can learn the behavior of scheduling algorithms and launch attacks to get scheduling priority and/or to create traffic panic and congestion. These attacks can compromise the system and significantly increase traffic delay and make TSC completely ineffective. In this paper, we compare the performance of different backpressure-based scheduling algorithms when they are under attack. We consider four different backpressure-based schemes, namely, delay-based, queue-based, sum-of-delay-based, and hybrid scheme that combines delay-based and queue-based schemes. We consider time spoofing attacks where individual vehicles arriving at an intersection can alter their arrival times. Through detailed simulation analysis we show that while the delay-based scheme has better fairness performance, it is more vulnerable to time spoofing attacks than the other schemes. We explore drawbacks of the delay-based scheme under different scenarios including non-homogeneous arrivals both for isolated intersection as well as multiple intersections. This study throws light on how to prevent time spoofing attacks on next generation TSC.