The Metropolitan Transportation Performance Evaluation

The problem of urban transportation has become an important issue that affects normal urban function exertion and urban continuable development, and it needs to be solved urgently. As a precondition to solve the problem of urban transportation, evaluating transportation performance validly also becomes more significant.The early indexes (for example, saturation, travel, speed, delay, and so on) are mostly non-probability parameters, but traffic data have stochastic trait, so these parameters cannot rightly describe the traffic flow characteristic, and it will bring some trouble to transportation management and transportation planning. Basing on stochastic characteristic of transportation system and considering the reliability analyses of civil engineering network system and the theory of blur, the article puts forward a probability index, namely unblocked reliability, and provides a method which can be applied to evaluate road network effectively.As a probability index, the unblocked reliability not only evaluates the stability of existing road network performance availably, but also can estimate the intending road network performance. This index has comparative characteristic that can be applied to discriminate the different city transportation performance, consequently to find disfigurements of urban transportation and help urban development. The index also can be applied to the system of traffic management; traffic information, dynamic route guiding and parking, in the end bring convenience to people.