Ballroom Intersection Protocol: Synchronous Autonomous Driving at Intersections

Abstract

Road intersections are considered to be serious bottlenecks in urban transportation. More than 44% of all reported crashes in U.S. Occur within intersection areas, which in turn lead to 8,500 fatalities and approximately 1 million injuries every year. Furthermore, because traffic traveling in one direction is generally stopped at busy intersections to allow traffic to flow in another direction, an intersection creates traffic congestion and frustration. The impact of road intersections on traffic delays leads to enormous waste of human and natural resources. According to the 2011 Urban Mobility Report, the delay endured by the average commuter was 34 hours, which costs in aggregate more than $100 billion each year in the U.S. With the advances in Cyber-Physical Systems (CPS), autonomous driving as a part of Intelligent Transportation Systems (ITS) is likely to be at the heart of urban transportation in the future. Autonomous vehicles have been demonstrated successfully at the DARPA Urban Challenge. General Motors' Electrical-Networked Vehicle, CMU's autonomous vehicle and Google's car are just a few other recently unveiled examples. Therefore, it is critical to address safety and throughput concerns as one of the main challenges for autonomous driving through intersections. In this paper, we propose a spatio-temporal technique called the Ballroom Intersection Protocol (BRIP) to manage the safe and efficient passage of autonomous vehicles through intersections. To achieve high throughput at intersections, BRIP aims to maximize the utilization of the capacity of the intersection area by increasing parallelism. By enforcing a synchronized arrival of autonomous vehicles at intersections, BRIP allows vehicles approaching from all directions to simultaneously and continuously cross without stopping behind or inside the intersection area. Our simulation results show that we are able to avoid collisions and increase the throughput of the intersections by up to 96.24% compared to common signalized intersections. Under BRIP, the optimal intersection capacity utilization of 100% is achievable in certain cases.