To strengthen, reinforce and partly demonstrate the developments of TRAMAN21, to increase its deployment prospects, but also, last not least, to enable sensible traffic flow improvements even under the current conditions, it was deemed crucial to include in the planned TRAMAN21 activities a local control system field test on a motorway that will deliver genuine operational evidence and preliminary realistic quantification of the benefits induced by the proposed control approach.

Task 4.1: Organisational Issues

To prepare for field test discussions, an appropriate text document, describing the background and motivation, the intended field trial, the proposed duties and responsibilities of both main field trial partners, i.e. of the responsible Road Authority and of the TRAMAN21 research group, has been prepared. The aim of the document is to serve as a proposal and basis for discussion with potentially interested Authorities.

During the start-up phase of the project, the PI contacted some potentially interested Road Authorities to identify a suitable motorway site for the field test. The motorway that has been selected is the M80 motorway in Melbourne, Australia. Organisational issues have been arranged with VicRoads, the corresponding Road Authority.

In addition, the project has also held intensive discussions with Highways England, the responsible Authority for motorways in England. An agreement has been reached for carrying out innovative control strategy development and simulation-based testing for a pilot motorway site; the possible subsequent field implementation remains an open option.

Task 4.2: Design and Implementation

The field test at the M80 motorway in Melbourne, Australia, addresses a major daily active bottleneck and employs local controllers. Conventional VSL signs are considered as actuators because they are already available at the selected site and can be used as a surrogate of some VACS (vehicle speed control) that are currently under development. Two controllers have been designed. The first one is an occupancy-threshold-based controller for VSL switching, aiming mainly at increasing, if possible, the bottleneck capacity. The second and more significant one is a feedback control strategy, originally proposed for MTFC (Mainstream Traffic Flow Control) enabled via VSL that has been extended considering multiple bottleneck locations. These controllers have been tested in simulation using a validated second-order macroscopic model. The field test implementation for the first controller was conducted early 2016, while the actual field test took place during July-August 2016. The field test implementation for the second controller is currently underway.

Design work has also started for the control design and simulation-based investigations for the Highways England site. A generic integrated motorway traffic flow control concept has been developed. It is based on the combination and suitable extension of control algorithms and tools proposed or deployed in other studies, such as ramp metering or VSL-enabled cascade-feedback mainstream traffic flow control, and allows for consideration of multiple bottlenecks. The new controller enables coordination of ramp metering actions at a series of on-ramps; as well as integration with VSL control actions; towards a common control goal, which is bottleneck throughput maximisation. The approach enables a pre-specified (desired) balancing of the incurred delays upstream of the employed actuators, via a suitably designed knapsack algorithm. The control algorithm has been tested using real data from a pilot motorway site in England.

• Iordanidou, G. R., Papamichail, I., Roncoli, C., Papageorgiou, M.: A feedback-based approach for mainstream traffic flow control of multiple bottlenecks on motorways. 19^th IFAC World Congress (IFAC'14), Cape Town, South Africa, August 24-29, 2014, pp. 11344-11349. -LINK-
• Iordanidou, G. R., Papamichail, I., Roncoli, C., Papageorgiou, M.: Feedback-based mainstream traffic flow control for multiple bottlenecks on Motorways. IEEE Transactions on Intelligent Transportation Systems, 2015, vol. 16(2), pp. 610-621. -LINK-
• Iordanidou, G.R., Roncoli, C., Papamichail, I., Papageorgiou, M.: Integrated motorway traffic flow control with delay balancing. 14^th IFAC Symposium on Control in Transportation Systems, Istanbul, Turkey, 18-20 May 2016, pp. 315-322. -LINK-
• Iordanidou, G.-R., Papamichail, I., Roncoli, C., Papageorgiou, M.: Feedback-based integrated motorway traffic flow control with delay balancing. IEEE Transactions on Intelligent Transportation Systems, 2017, vol. 18, pp. 2319-2329.
• Papamichail, I., Iordanidou, G.-R., Roncoli, C., Papageorgiou, M.: Integrated motorway traffic flow control. 8^th International Congress on Transportation Research in Greece, Thessaloniki, Greece, September 27-29, 2017.

Task 4.3: Demonstration and Evaluation

The first part of the control algorithm to be field tested at the M80 motorway in Melbourne, Australia, i.e. the occupancy-threshold-based controller for VSL switching, was actually field-applied, and the corresponding field-demonstration took place during July-August 2016. The main conclusions from the related analysis of traffic data are the following:

• Sufficient compliance of drivers to the displayed VSL is achieved, and the mean speed is reduced according to the displayed VSL.
• Switching to lower VSLs has as a result an immediate increase of occupancy.
• The average impact of switching to lower VSLs on the fundamental (flow-occupancy) diagram at undercritical occupancies is a visible slope decrease.
• The VSL-induced critical occupancies are usually higher for lower VSLs applied.
• A delay on the onset of congestion cannot be confirmed for the specific infrastructure when using the VSL algorithm at the bottleneck area.
• A capacity increase for moderate displayed VSL cannot be confirmed for the specific infrastructure.

The second (and more important) part of the control algorithm to be field tested at the M80 motorway in Melbourne, Australia, i.e. the feedback control concept, is currently in the field-application phase. Demonstration and evaluation of the strategy will follow.

Last updated on 28/2/2018.