Xiangfeng Ji

Deriving Travel Behavior Data of Urban Subway Passengers from Mobile Phone Network

The subway is an important transportation mode in large cities. Subway operators need travel behavior data of subway passengers to improve their service level. In this paper, a traffic collection method based on wireless communication technology is reviewed and compared. A method to derive information from cell-ID and HO data based on the special settlement of underground mobile communication base stations is proposed. The passenger volume and travel time -- in both the subway network and subway station -- can be drawn, which will support the operation management and travel navigation.

Moment-based travel time reliability assessment with Lasserre’s relaxation

ABSTRACT This paper proposes the generalized moment problem (GMP) to assess total system travel time (TSTT) reliability on a traffic network. As a distribution-free method, the proposed approach only needs moment information of uncertainty to make the evaluation. In the GMP, upper bound of the probability that TSTT exceeds some predefined threshold value (which is called unreliability function) is the objective, and moment information of uncertainty is formulated as constraints. Based on the first moments and support information of total link travel time of each link, we use Lasserre’s relaxation to reformulate the GMP as a semi-definite programming, which can be solved efficiently. We test the proposed method on traffic networks of different sizes. Numerical results show that the upper bounds obtained with our method are tightest in most cases and show different tail information. The results may also bring some useful insight to applications of the moment-based method in practice.

Discriminance of Activation Time for Bus Dispatching under the Environment of Intelligent Vehicle-Infrastructure Cooperation

Discriminance of activation time for bus dispatching is a basis for the efficient bus operation. In this paper, bus arrival time prediction model is developed based on the calculation of travel time, dwelling time at the station, and intersection delay. Real-life operational data are used to verify the reliability of the proposed model. Besides, a novel mechanism called lateness recovery is proposed as an on-line dispatching mechanism to render the late buses back to the normal operation. Underlying the proposed lateness recovery is the time deviation coefficient and critical time deviation coefficient. The mechanism lateness recovery is demonstrated with the real-life bus operation data. The communicate content and architecture for bus dispatching timing are designed under the environment of Intelligent Vehicle-Infrastructure Cooperation (IVIC).

Location-based route choice model under random regret minimization

In recent years, the random regret minimization (RRM) model has arisen as the counterpart of the random utility minimization (RUM) model in the transportation analysis. In the conventional RRM model, the inability to account for the route perception variance is shown with a two-route small network. Considering the route length of different alternatives, a location-based model is proposed in this paper. In the newly proposed model, two ratios - including the ratio between considered regret and alternative route travel time and the ratio between considered route travel time and alternative route travel time - play an important role in the modification. With the proposed model, the choice probability for the two-route testing network is calculated again and the anticipated choice probability is shown. With a medium-sized traffic network, the choice probability for different routes restricted to a specific Origin Destination (OD) pair is also calculated to demonstrate the effectiveness of the newly proposed model.