Expanding transport capacity requires measures such as increasing the number of trains or increasing the number of cars per train, etc. However, the number of trains which can be operated is limited by the operation method and facility conditions for the railway division in question, and this limit is expressed as the track capacity.
Track capacity is affected by the train type, train arrangement, running time between stations, block system, presence of relief tracks and other factors. Also, the proportion of the track which can be effectively used is called the track utilization ratio, and while this ratio varies according to railway division characteristics such as service times and maintenance intervals, it is generally between 50 and 75%.
When calculating the track capacity, a track utilization ratio of 60% is normally used.
(1) Track capacity for single-track sections
The track capacity is calculated using the formula below.
1440: 1 day (24 hours)×60 min.
T: Average running time per train between stations (min.)
C: Block handling time (min.)
Automatic block system: 1.5 min.
Non-automatic block system: 2.5 min.
f: Track utilization ratio: 0.6
For way of reference, track capacities calculated based on the relationship between the type of block system and the average running time between stations are shown in Table 5.
Table 5 Track capacity (number of in-bound and out-bound trains)
Automatic block sections allow continuous trains to be set by establishing block signals, and provide a track capacity approximately 10% greater than that for non-automatic block sections.