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Intelligent Transportation Systems (ITS) have the potential to improve traffic conditions and reduce travel delays. As a decision support software system for ITS, DynasTIM is based on the principle of dynamic traffic assignment and developed for real-time online simulation, prediction and optimization of dynamic traffic flows in urban or expressway networks. This paper introduces the models, algorithms and some typical applications of DynasTIM. The main contents include: the functional architecture; the application architecture of the system; dynamic OD (Origin-Destination) flows estimation method with novel formula for assignment matrix computation; mesoscopic traffic model using variable-length speed influence region and calibrating speed online based on connected vehicles data; and parallel SPSA algorithm based urban area signal optimization method. The functions of DynasTIM are implemented basically through three main modules: state estimation (ES), state prediction and control strategy optimization (PS&CSO), and guidance strategy optimization (GSO). The case study is aimed at the populated Futian Central Business District (CBD) road network in Shenzhen, China, which has an area of about 7 square kilometers. Based on the archived turning counts collected from 359 video traffic detection locations, DynasTIM was calibrated offline for this network, in order to validate the capability of simulating actual traffic conditions, and to set up basic conditions for testing signal optimization methods. The results show that the simulation output flows of DynasTIM have fairly good matching accuracy with the real surveillance flows in the field. Furthermore, for the CBD network with 38 signalized intersections, the signal optimization method is evaluated and better signal timing plans are found which can reduce about 13% average travel delay, compared with the signal plans currently implemented in the field. Full article

The central business district (CBD) has become the economic powerhouse of contemporary cities. China’s economic transition from world factory to a knowledge-based economy underpinned the development of hundreds of CBDs over the course of less than two decades. The plans promoted land use diversity and the incorporation of service facilities in the support of business function, but a rather different service environment emerged. Taking the Futian CBD of Shenzhen as the prototypical case, we examined the distribution, vitality, uses, and users of these facilities, which are largely built up by the private sector and without governmental support. A questionnaire sent to users and data derived from social media reveal that the vast majority of visitors of these service facilities do not work in the CBD and travel via the reformed mass transport system to this location. The high-quality public spaces and street environment, as well as the numerous service facilities, many of which are at a low economic order, attract people from all over the vast city, which homes over ten million, highlighting a new role for the CBD as a civic center. In contrast with the globalized business sought after by government and business leaders of the CBD, a new populist nexus is emerging and without significant support. Full article