(6) Reinforcement and replacement of deteriorated structures
1.2 Increased Transport Capacity
Increased transport capacity is called for when transport demand rises over railway sections, and the means to achieve it are diverse.
Typical methods include increasing the number of trains, lengthening train make-up and enlarging cars, each of which critically affects track and structures.
Although at first glance, increasing the number of trains may not seem to affect railways, as long as the tracks form a structure which must sustain its functions by restoring the damage caused by train loads through maintenance, this work only stands to increase. Moreover, maintenance work is carried out during the interval between trains, so reductions in track maintenance time must also be taken into account.
We must also consider that once the number of trains exceeds prescribed limits, relief tracks must be built and the main track added, increasing targets for maintenance.
In addition to the work described above, relief tracks may need to be extended if train make-up is lengthened.
Enlarging cars has a more significant effect. This problem cannot be covered by maintenance work, and as there is a risk that it will lead to the destruction of materials comprising the track structure, it often calls for the improvement of parts. Structures, especially bridges, must be reviewed in detail, and reinforced and replaced as necessary.
1.3 Higher Speeds
Higher speeds are the eternal pursuit of mankind, and a key element in the competition with other means of transport. We are now in an age where a speed of 300 km/h on broad gauge lines is a reality, and the race is on for 350 km/h. Furthermore, linear motors capable of running at 500 km/h are undergoing service tests.
Although there are many minuses with narrow gauge lines compared to broad ones, they are also capable of high speeds. Level crossings with roads present a greater obstacle than gauge.
In terms of maximum speeds, in Japan today, test run with a speed more than 160 km/h along some narrow gauge lines is already realized, and 200 km/h is being pursued.
As for operating speeds, as shown in Fig. 1, speeds of 140 km/h have been achieved over a single-track section, specifically Seikan Tunnel, and 130 km/h over multiple-track sections.
However, while users are demanding shorter traveling times to their destination and special fast delivery of freight, they are not seeking speed thrills on a roller coaster ride.
A higher maximum speed is one good way to achieve this. However, along some railway sections, any one or combination of measures such as increasing speeds through curves and
