One of our interests is to investigate the dynamics of traffic flow through the microscopic properties of each vehicle in traffic. We mainly focus on microscopic models since we can easily incorporate human reaction delays in these models.

What we mean by delay here is the amount of time it takes to make a decision (e.g. braking) upon receiving a stimulus from outside the vehicle. In this sense, there are two main sources of delays while driving

  1. Physiological states of human drivers
  2. Mechanical features of vehicles

In our approach, microscopic models are based on following one or more leader vehicles, and this suggests a way of dynamically coupling the vehicles with a unique feature that coupling exists only between the vehicles upstream (opposite direction) of the traffic flow. This is a natural consequence of following in general the vehicles ahead but not behind.

We again combine the traffic flow characterization problem with our expertise on delay differential equations, graphs, frequency sweeping techniques and stability charts. With these unique tools in hand, we investigate the following open problems:

  1. Presence of multiple delays (delay heterogeneity) due to different sensing capabilities of humans (e.g. sensing time of velocity changes is different than sensing time of position changes)
  2. Extraction of stability charts to explain the contribution of different scales of delays to traffic flow stability
  3. Utilization of stabilty charts along with string stabilty analysis to derive conditions for stable traffic flow.
  4. Investigation of how traffic flow is affected in presence of more/less aggressive drivers following each other.

We see the impacts of our research in the following areas

  1. Understanding hybrid traffic flow where human and automated vehicles travel together
  2. Designing better cruise control or decentralized vehicle cruise control for improved traffic flow
  3. Design of (semi) active driver assistance systems in order to improve driver awareness
  4. Research on inter-vehicle communication technologies.