A seamless multimodal transit system has been a goal for transportation planners and users. Owing to the developments of advanced public transportation and telecom technologies such as automatic vehicle location (AVL) and real-time passenger information system, key just-in-time (JIT) concepts can now be realized in process design and coordinated scheduling to shape a seamless multimodal transit system. JIT refers to a production system that times both movements of goods during production and delivery from suppliers together. It meets the same logic for seamless multimodal services. Therefore, this study innovatively analyzes possible public transportation technologies for JIT uses; moreover, to layout the possible application frame-work of a transportation technology based JIT multimodal transit system for main station area in Taipei city. With this innovative framework, multimodal transit services can deliver to the right place at right time.
Japanese motor maker Toyota originates JIT production concepts in 1973. During 1979-1980, after the Japanese industries had shown their high quality and efficiencies in production for years, many U.S. enterprise executives and university professors visited Japanese companies and found this critical idea-JIT [1]. After that, many famous U.S. companies switched their plants to the JIT system.
Mr. Ohno, vice-president for manufacturing of Toyota motor company, devised this new production system based on the reducing or elimination of waste from manufacturing, purchasing, manufacturing support, and distribution activities [2]. However, the meaning of “waste” is different for Japan and the U.S. The original Toyota definition of waste is “anything other than the least amount of equipment, materials, parts, and working time essential to production.” The U.S. defines it in a clearer way, as “anything that does not add value to the product” is the waste, and it also became the classic definition of waste from then on [3].
In a JIT system, just-in-time can eliminate waste, which means any items of production or service only move through the production system when needed [1]. More clearly, it refers to a production system that times movement of goods during production and delivery from suppliers together so that the batch arrives for processing nearly after completing the first batch. The JIT process results in no idle items, idle workers, and idle equipment wait to process.
The concept behind JIT is similar to a pull system [4]. Units of production or service pulled to just where just as needed. A pull system requests delivery and production from higher levels to satisfy the exact units necessary in lower levels. Moreover, with the pull system, inventory moves only as needed, and the ideal lot size is one piece. This method can cut excess inventory that hid production and quality problems. The hidden problems of production become clear and continuous improvement for quality then works.
In transportation industries, JIT can adopt for logistics and multimodal freight transportation for years [5,6]. Though, for the passenger transportation industries, the JIT is a brand new technique [7,8]. The delivery of goods is easier than transporting the people since the latter one is more dynamic and hard to predict. However, thanks to the mature public transportation and telecom technologies, now the key JIT concepts may realize in process design and coordinated scheduling to shape a seamless multimodal transit system [9-11]. On these grounds, the paper aims to point out some critical JIT concepts which are useful and applicable for multimodal transit services, and on the contrary, to select applicable existing public transportation technologies for JIT. Moreover, the paper tries to layout the possible application framework of a transportation technology based JIT multimodal transit system for main station area in Taipei city.
2. JIT Methods
JIT defines seven wastes in operations, which come from overproduction, waiting time, transportation, inventory waste, processing, motion/movement, and product defects. Therefore, the goal of a JIT system is to meet “Seven Zeros.” They are [1,2]:
• Zero Defects: to avoid delays due to defects
• Zero Lot Sizes: to avoid “waiting inventory” delays
• Zero Setups: to lower setup delay and produce small lot sizes
• Zero Breakdowns: to avoid stopping tightly coupled lines
• Zero Handling: to promote flow of parts
• Zero Lead Time: to make sure rapid replenishment of parts, and
• Zero Surging: to avoid unnecessary WIP (work-inprocess) buffers.
In details, some aspects of process design that are particularly important for just-in-time systems might include: small lot sizes, reduction of set up time, limited WIP, improving quality, production flexibility, and small quantity of inventory storage [2]. Key elements of JIT can catalog as product design, process design, personnel management, and production planning, as shown in Table 1.
Moreover, this study selects “Kanban Management System” and “Small Lot Mixed-Model Production” as the critical JIT techniques for multimodal transit uses. They can illustrate as follows.
2.1. Kanban Management System (Pull Method)
Figure 1 shows the theoretical concepts of Kanban management. There are m bus routes and n stops in this figure. The Movement of Kanban stands for signal/information feedback and capacity move stands for the exact capacity supply corresponding to the signal/information demand.
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