A TRAFFIC ASSIGNMENT PLANNING MODEL: THE LOAD-NODE CONCEPT
Abstract The use of the traffic assignment model in urban transportation planning is universal; however, traffic assignment in its present form is expensive, cumbersome, and has serious limitations. In this research the authors have developed and tested the load-node concept of traffic assignment which reduces many of these problems. In the load-node concept the corners of zone boundaries are used for points of trip origins and destinations. In this manner the zone centroids and associated connector linkages of the network are removed. This results in a substantial reduction in network coding. In this study the total number of nodes required to define the network decreased by almost 3000 to 995 and the number of links in the network decreased by two-thirds. The forecasted 1990 Phoenix metropolitan area was used to test this approach and the average link volumes of all-or-nothing capacity restraint assignments using both the load-node and zone centroid concepts formed the basis of the comparison. The analyses indicated the average link volumes of the two concepts are comparable. A probable reduction in computer time of 40 + per cent was obtained when the load-node concept was used. The authors suggest that this approach is primarily adaptable for planning purposes and not design. With respect to the design use of traffic assignment results, the travel between adjacent zones is seldom included in the major arterial street and freeway traffic volumes obtained from zone centroid assignment. This may result in a substantial underestimation of future traffic volume and turning movements particularly if stepped down 24-hr assignments are used for design purposes. The load-node approach does assign travel between adjacent zones.
The equivalence of transfer and generalized benders decomposition methods for traffic assignment
In prior work we have given an intuitive development of Transfer Decomposition, a decomposition of the traffic assignment problem into two traffic assignment problems. The intent of this paper is to provide a rigorous basis for this technique by establishing that it is a generalized Benders decomposition. As an illustration of the result, we give a decomposition algorithm that is based on the familiar Frank-Wolfe method.
Introduction and experience with the primary mail services based on their names for students
Kyushu University provided mail service based on student IDs such as "1AB10123X" to the university students for many years. Using this model, we had problems communicating with the students who graduated from the University and enrolled in the graduate school. The students received new mail addresses based on their new student IDs such as "2AB12789Y". Faculty members were forced to change the student mail addresses in the mailing lists and in their mail client address book. Furthermore, students were forced to notify the e-mail address change to all of their existing contacts. We introduced a new mail system to provide addresses based on the student name, as well as student ID in April 2011. The new naming convention uses the following format: lastname.firstname.999 where 999 is a random number of 3 digits. Students can select some combination patterns of their first and last names for Japanese. We also consider the middle names for foreign students. In the system implementation, we did not have the formal information of alphabetical names for students. We generated alphabetical names from Japanese Katakana names. It is not easy for us to get the appropriate name in this manner. We implemented a confirmation stage of the alphabetical name at first use, and then students can select their mail addresses for their convenience. We paid much attention to the user interface in the system. Since April 2011, the number of users who use the mail address based on their own name has been increasing gradually. This paper will detail the usage status of the new system.