Optimization model of number of scheduled freight train formation cars
The determination of the number of formation cars is an important part of making a scheduled freight train plan, and it also has a large influence on the benefits of railway freight transportation. First, the influences that affect the number of formation cars are analyzed. Secondly, taking the maximum freight transport benefits as an objective, and comprehensively considering the primary factors that include service frequency of freight trains, section traction weight, effective length of arrival-departure tracks, and so on, this paper establishes the optimization model of the number of scheduled freight train formation cars. Finally, the solving method for the model is presented, and a case is given to show the solution process. It provides a reference for decision-makers of railway freight transportation.
Study on the Minimum Number of Cars in Fixed-point Departure Mode
There are two kinds of departure mode of freight train in marshalling station, which are fixed-point departure mode and fixed-consist departure mode. In order to determine the model of minimum number of cars in fixed-point departure mode, this paper gives some assumptions on the condition of the departure mode, studies the operation index about the two departure modes and finds out the basic change principle. Furthermore, the paper puts forward five concepts, which include favorable minimum number of cars, benefit minimum number of cars, cost minimum number of cars, capacity minimum number of cars and model minimum number of cars, and gives the determination method of the variables corresponding to the five concepts. The study shows that the fixed-point departure mode of freight train is adapted better to the condition of smaller vehicle flow and shorter distance of running section.
MAXBAND: A PROGRAM FOR SETTING SIGNALS ON ARTERIES AND TRIANGULAR NETWORKS
MAXBAND is a portable, off-line, FORTRAN IV computer program for setting arterial signals to achieve maximal bandwidth. Special features of the program include (a) automatically choosing cycle time from a given range, (b) permitting the design speed to vary within given tolerances, (c) selecting the best lead or lag pattern for left-turn phases from a specified set, (d) allowing a queue clearance time for secondary flow accumulated during red, (e) accepting user-specified weights for the green bands in each direction, and (f) handling a simple network in the form of a three-artery triangular loop. Green splits can be provided or, alternatively, flows and capacities can be given and splits calculated by using Webster's theory. The program produces cycle time, offsets, speeds, and order of left-turn phases to maximize the weighted combination of bandwidths. The optimization uses Land and Powell's MPCODE branch and bound algorithm. As many as 12 signals can be handled efficiently. The program is available from the Federal Highway Administration. (Authors)