Mapping split cycle offset technique to signal frames based control

Central control by periodic adjustment of cycle time, cycle offset and phase split is common practice for centralized traffic control systems. Especially when public transport priority is required, a decentralized approach with signal frames is widely used throughout central Europe. Even though the notion of an offset is known in signal frame based control, the split is to be expressed by the signal frame design, and the cycle time cannot be changed dynamically except by a program change.

Therefore since many years these two approaches have been considered not compatible.

This paper shows a way how to use signal frame based control on the intersection level embedded in centralized control, basing on periodic cycle time, offset and phase split adjustment. The resulting system architecture will enable more local, operational intelligence within centralized traffic control systems.

Download the paper here: Montreal_EU-TP0760  [PDF, 448 KB]

Handling local traffic-actuated intersection control with V2I data

Local traffic-actuated intersection control is traditionally using detector measurements as inputs for its control decisions. Such input data might be vehicle counts or vehicle detection slopes. When controlling an intersection by V2I (Vehicle to Infrastructure) information, counts and slopes are not available, but vehicle GPS coordinates. There need to be transformation rules in order to be able to use the coordinates and ideally destination information of vehicles for local intersection control. The approach developed in this paper introduces segments on the approaches and the egresses of the intersection. Fill degree information of these segments can directly be used for the local intersection controller. Furthermore hybrid systems consisting of V2I and detection information can be controlled in the same way. The approach has successfully be tested in a closed test area and also in an open city area with mixed traffic.

Download the paper here: Copenhagen_EU-TP1042  [PDF, 609 KB]

A rule-based distributed network control approach

Network control captures and observes traffic, and decides and commands at the central level. The approach presented in this paper uses network control information to provide additional information to the controllers in the field. This shall improve their control decisions. The approach uses a rule-based network control that uses fixed rules in tables to send commands to the field controllers. In the simplest case, these commands are program switching commands, in the most advanced case a re-parameterization of the control program. This approach uses a systematic application of observer controller architecture to network control. Furthermore it keeps distributed control intelligence by delegating operational work to the local intersection controller. Operational work is the second-to-second decision process about keeping green, keeping red, going to green, or going to red for each movement. If restricting to stages, this is the stage change decision.

Download the paper here: Copenhagen_EU-TP1043  [PDF, 702 KB]