Despite the long-lasting research and developments worldwide, urban signal control is still an area susceptible of further improvements. The usually limited availability of space in the urban centres prevents the extension of the existing infrastructure, and, along with the continuously increasing mobility requirements, urge for solutions that will release the serious congestion problems through the best possible utilisation of the already existing infrastructure. From the control point of view, this may be translated into the employment of actuated systems that respond automatically to the prevailing traffic conditions. This is the aim of the TUC (Traffic-responsive Urban Control) strategy. TUC was initially developed and field-implemented in Glasgow, Scotland, within the European DRIVE III project TABASCO (Telematics Applications in BAvaria, SCotland and Others) as part of the integrated traffic responsive urban corridor network control strategy IN-TUC (INtegrated - Traffic responsive Urban Control). Control objective of TUC is the homogeneous utilisation of the capacity of the controlled urban network. This control objective is approached through the appropriate manipulation of the green splits at urban signalised junctions, while the cycle duration and the offsets remain unchanged. The control decisions of TUC are based on all real-time measurement data collected from detectors that are located within the controlled area. TUC is built upon well-known methods of the Automatic Control and Optimisation theories. This allowed for the development of a strategy robust with respect to measurement inaccuracies so as to be able, even in cases of insufficient data, to react correctly to the current traffic conditions, and simple so as to permit the execution of all required calculations in real time. Moreover, TUC has been developed in a generic way so that it may be transferred with minor modifications to networks with arbitrary topology and characteristics.

For more information on the TUC strategy you may see the following:

1. Diakaki, C., M. Papageorgiou, and partners of the Transport Telematics Project TABASCO (TR1054). Urban Integrated Traffic Control Implementation Strategies. Report for Transport Telematics Office, Brussels, Belgium, September 1997.
2. Diakaki, C., M. Papageorgiou, and T. McLean (1999). Application and evaluation of the integrated traffic-responsive urban corridor control strategy IN-TUC in Glasgow. Preprint CD-ROM of the 78^th Annual Meeting of the Transportation Research Board, Washington, D.C., U.S.A., January 10-14, paper no. 990310.
3. Diakaki, C., M. Papageorgiou, and K. Aboudolas (1999). Traffic-responsive urban network control using multivariable regulators. Proceedings of the International Conference on Modeling and Management in Transportation, Poznan/Cracow, Poland, October 12-16, Vol. 2, pp. 11-16.
4. Diakaki C. (1999). Integrated Control of Traffic Flow in Corridor Networks, PhD Thesis, Technical University of Crete, Department of Production Engineering and Management, Chania, Greece.
5. Diakaki, C., and M. Papageorgiou (1999). The Co-ordinated Traffic-responsive Urban Control Strategy TUC. 5^th Delta Report for Daimler-Benz AG, Stuttgart, Germany, December 1999.
6. Diakaki, C., M. Papageorgiou, and K. Aboudolas (1999). A multivariable regulator approach to the traffic-responsive network-wide signal control problem. Accepted for presentation at the 9^th IFAC Symposium on Control in Transportation Systems 2000, Braunschweig, Germany, June 13-15.