Ensuring safety is an essential requirement not only for transport operations but for all industrial sectors. In addition, there are also increasing demands for improved operation efficiency.
Transport operations in particular require safety, accuracy and swiftness. To achieve these goals, the operated cars, tracks and signal safety facilities, etc., are provided as transport facilities and an appropriate train operation plan is prepared based on these facilities.
When improving train operation duties, it is necessary to constantly keep in mind the basic philosophy of preventing train accidents. Transport facilities should be improved to match the traffic demand over the railway division in question with special priority given to signal safety facilities, and operational standards which clearly demarcate people's and machine's roles should be established by adopting modernized facilities.
This paper presents an overview of signal safety facilities, which comprise important transport facilities for railways in Japan, from the viewpoint of operation handling as a reference for operation planners.
2 Outline of Railways in Japan
Japan has a total land area of roughly 378,000 ?2 and a population of approximately 123 million people.
Japan's railways form a vast network which stretches throughout the entire country. Traffic volume for urban and inter-urban railways during FY 1993 is shown in Table 1. (Railways Viewed Through Numbers 1995)
Of these, JR railways form a nationwide network which connects the main island of Honshu with the islands of Hokkaido and Kyushu by tunnels and the island of Shikoku by a great bridge. With this network, Japan's major cities are linked by the Shinkansen which features a maximum speed of 270 km/h and conventional high-speed lines with maximum speeds between 120 and 130 km/h.
For way of reference, operated Shinkansen lines total roughly 2,050 km, and transport approximately 270 million passengers annually (about 700,000 passengers per day). 33% of JR lines are double tracked, and 55% are electrified.
Looking at domestic transport share by means of transport, railways account for 27.7% of passenger transport (passenger cars: 62%, bus: 10%) and 1.2% of freight transport tonnage (automobile: 90.5%. inland sea transport: 8.2%).
