Parallel Simulation Technology

PIM/Paracell Application Notes

  • Central JR Shinkhansen Simulator
  • Baggage Handling Systems
  • General Motors Paint System
  • Manufacturing Agility Server
  • PST Home
  • PST Product Information
  • PIM/Paracell Presentation
  • PIM Configurations
  • Product Documentation
  • Application Notes Main
  • PST Staff
  • PST Links
  • PST Download Page
  • PST Inquiry

  • Central JR Shinkhansen Simulator


    Takashi Kawakami, manager of information system development at Central Japan Railway Company, was pondering in 1992. It was time to plan the next generation of their COMTRAC (COMputer aided TRAffic Control) system, the Shinkansen (Bullet Train) control and monitoring system.

    The Tokaido and Sanyou Shinkansen Lines between Tokyo and Hakata, 1,100 km (700 mi) long, are the busiest among all the Shinkansen lines. On averrage, the lines carry 300,000 passengers everyday, with a peak of 1 million per day, on about 1,000 trains at a speed of 270 km/h (170 mph). This is something like 4,000 Boeing 747's flying back and forth between San Francisco and Los Angeles. They must increase the train frequency, keep the minuscule operation error of 15 to 30 seconds, while maintaining their safety legend--no passenger accidents in the thirty year history.

    Central JR was wondering to what extent they could improve the next generation system. They were also wondering how they would test the new system and train the dispatchers. On the other hand, they had had enough of long delivery and high cost of computer systems and application software. These information systems, including minor modifications, had always been contracted to a few mainframe computer manufacturers. These systems had become black boxes for the user, Central JR.

    A new agent-based and complexity-based parallel computer and software concept was introduced. Kawakami of Central JR quickly recognized that his staff, without programming experience, could build information systems on their own using the PIM and Paracell. They could test what-if simulations on the do-it-yourself systems and evolve the systems by themselves. These systems simulate operations as realistically as the real complex world would be, giving proof to the plans, developments, designs and schedules of the railway system.

    Railroad system simulators are a natural application for the products. With any conventional programming scheme and computer it would have taken as much time and cost to build a simulator as a real control system. Paracell, the programming language, and the PIM, the parallel execution machine, made it possible to build such a simulator at less than one third of the cost originally estimated.

    Central JR has proved all of three major advantages of the PIM/Paracell system with building the simulator. First, the simulation is real time and the central control computer cannot identify which is the real train operation or the simulator. Yaskawa Electric Corporation, the supplier, did no application program coding at all. Application programming was accomplished by domain experts - not programmers - from Central JR. Third, the simulator easily scaled up from the first small scale trials, ending up as a large scale system to cover the whole distance of 1,100 km (700 mi).

    Satisfied with the success of the simulator for their development, Central JR is going forward to include the PIM/Paracell simulator on on a much larger scale for the next generation Shinkansen Operation Control and Monitoring (COMTRAC) system.

    The Tokaido and Sanyo Shinkansen (Bullet Train) System

    The Shinkansen operation started in 1964, over three decades ago. Operations began running one Hikari super express and one Kodama super express per hour. The Hikari and Kodama lines had the same performance of 210 km/h (130 mph), but Hikari stopped at only major stations and Kodama stopped at every station between Tokyo and Osaka, covering 500 km (300 mi). Today, there are three classes of bullet trains: Nozomi, Hikari and Kodama are running along the Tokaido and Sanyo lines between Tokyo and Hakata, a distance of 1,100 km (700 mi).

    Nozomi has the fastest operation, running at a speed of 270 km/h (170 mph). During peak hours, trains arrive and depart the Tokyo station every three and a half minutes. The train frequency today is one Nozomi, seven Hikaris and three Kodamas per hour compared with just one Hikari and one Kodama 32 years ago. The JR company is planning to add another Nozomi soon and then one more per hour. Despite this heavy traffic, the system operates right on schedule with a minuscule error of 15 to 30 seconds, most of the time. There has not been a single passenger accident in the 32 years history of Shinkansen.

    Developing schedules involves months of work for quite a few railway experts. They know what affects the train operations: available trains, maintenance cycle, available drivers, different train performance, stations, distance, signals, track switches, curves, slopes, tunnels, bridges, and so on. Even extra trains must be scheduled in advance, yet there is no way to run ad hoc trains. Can they apply a big change all at once? No, when they started the Nozomi 270 km/h super express, only four of those per day could run only early morning and late at night. It took several months before hourly operation of the Nozomi began.

    There is a bottleneck near the Tokyo terminal station, the busiest station. Since the Tokyo station has no hind tracks, arriving trains and departing trains must cross over the main tracks. To make things worse, the train yard is located before the terminal station, not in hinterland, so that deadhead trains must travel for a while on the busy main tracks. To reduce this problem and increase the train frequency, Central JR is planning to build another terminal station, Shinagawa, a few miles before the Tokyo station. They must check the effects of the new station before actual construction occurs.

    On January 17, 1995, a big earthquake destroyed the Kobe Shinkansen station and nearby tracks a few minutes before the train operation of the day began. If it were after, a couple of trains with more than 1,000 passengers could have crashed down to the ground. Japan Railway barely escaped the death of their safety legend. The train operation in this area had to be shut down for 100 days. JR was losing US$15 million every day during that time.

    The big earthquake in Kobe convinced Japan Railway to build the second control center in Osaka in addition to today's sole control center in Tokyo. The two centers will work as a back-up system. When one center is on-line, the other is used to train the operation center dispatchers. They need a simulator system to work with the back-up system for dispatcher training.

    The 300 km/h (190 mph) trains are already in test and will soon be put into operation. They are planning even faster trains (200+ mph). New trains with different performance will make the already complex system and its scheduling more complicated. There might be undesirable emergent, chaotic, behavior. They need a simulator system to check this.

    If, for example, snow causes a delay, what happens? The whole system goes out of control. Of course, there is no real danger to passengers. The problem is that nobody knows the new schedules even after the cause of the delay is removed. The train drivers know only the original schedules instead of the new feasible ones. Thus, every driver tries to catch up with the original schedules. Soon, several trains are stuck following a train that stops at a station. As soon as the leading train leaves the station, all of the following trains start at once causing a peak power demand to the power substation. They want to know when the flock of trains hits the busiest Tokyo station. They want to model revised, seemingly feasible schedules on a simulator system that performs in faster-than-real-time mode.

    Central JR sought to improve these situations to increase the train frequency and to make the schedules more flexible. In addition, they had several ideas for improved service. However, prior to designing and implementing an eintirely new system, they have to test the ideas. But, how? They required a simulator at a reasonable cost that provided quick turnaround time, and the ability to experiment with different scenarios easily. Conventional simulators are either too simple to predict system behavior or too expensive and slow to be practical.

    Building a Simulator for the Shinkansen System

    The Shinkansen tracks are segmented into1.6 km (1 mi) lengths between stations. Lengths in stations and their neighborhood are much shorter. The total number of track segments far exceeds 1,500 since the eastbound and westbound tracks alone are about 1,100 km (700 mi) each. Each track segment is the basic unit of control for the train traffic and includes several relay logic elements. Track segments are locally interlocked and generate signals for the following segments. Some of the relay logic signals are sent to the central control system every three seconds.

    The central control system sends traffic control signals including speed limit information and route control commands, i.e., track switching command, based on the train schedules and tracking data. At peak hours there may be 130 or more trains on the tracks, and the shortest period between trains is three and a half minutes. The number for the day is about 1,000 trains.

    The Shinkansen simulator developed includes about 1,000 train agents, 130 or more of which may be on the track at a time, and 2,000 track segment agents. These agents work in parallel. Simulating this system with a conventional programming scheme and computer would require a very large effort and a long time in systems design, flowcharting, coding and debugging; the resulting simulation would be brittle. In addition, it would be hard to divide the task among many people and nearly impossible to complete it in a short period of time.

    The programming and execution scheme of the PIM/Paracell system simulates teamwork with a bulletin board and a clock. The team members are to get data only from the bulletin board and to post results on the same board. They don't need to have time-consuming meetings. The clock frees them from directly acknowledging their communication with each other. Adding members does not increase overhead. Each can concentrate on his own task, yet a concerted job can be achieved through the bulletin board and the clock.

    This programming and execution scheme of the Paracell/PIM system mapped perfectly to the desired implementation. Programming individual small computing cells, or agents, that are to run in parallel and in synchronization allows for train and track agents to be quickly implemented and scaled up as needed. The concept of communicating between agents only through the common global memory supports the need to have a single coherent image of the system status for running the simulation. This model fits the structure of the Shinkansen system very well.

    The actual simulator system consists of nine Macintosh computers, each housing 1,000 PIM cells. Communication between systems is via Ethernet. One of the units works as the central machine and eight others simulate the 39 stations and yards that make up the entire Shinkansen system. The application program was coded by JR engineers using Paracell, a rule-base near-natural declarative language. They did not necessarily have programming experience. Rather, they had knowledge about the problem they were trying to solve, and ideas about how to solve them. The simulator is their product, not the supplier's, and they have a strong motivation to improve the product further.

    Simulator for the Next Generation Shinkansen System

    Central JR has proved all three major advantages of the PIM/Paracell system by building the simulator. First, the simulation is real time and the central control computer cannot identify which is the real train operation or the simulator. When they want prediction of train operations, the simulator can run even faster-than-real-time. Second, application programming was accomplished by Central JR people without programming experience. The number of lines of code in a conventional programming language would likely have been ten times more than the actual code in Paracell. Third, the simulator ended up as a large scale system to cover the whole distance of 1,100 km (700 mi). It was a simple linear effort scaling up from the first small rial for a few miles near the Tokyo station to a full-scale operational simulation.

    Satisfied with the success of the simulator on the Mac-PIM, Japan Railway decided to include a simulator subsystem in their next generation Tokaido and Sanyou Shinkansen Operation Control and Monitoring System. It will be up and running by 1998. The simulator subsystem will be used for testing fault-tolerant central control computers. In addition, it will be used to train the dispatchers for both normal and emergency operations. Finally, it will test be used to test many what-ifs conditions as a means of integrating new technologies, equipment, and concepts into the Shinkhansen operations. For this next phase, a PIM system based on the PowerPC and VME technology will provide over 20,000 PIM cells for better reliability and more than double the capacity fo the original PIM-based COMTRAC system. With this capacity, they will be able to expand the scope of simulation to inlcude such areas as power supply and demand between trains and substations.


    Railroads are complex. Yet the PIM/Paracell system has proven capable of simulating the Shinkansen. This technology can describe, simulate, and find solutions to many complex problems.


     Parallel Simulation Technology LLC.
    Sunrise Labs
    25 Constitution Drive
    Bedford, NH 03110 USA
    Telephone: 603-644-4500 / Fax: 603-622-9797