In Japan, track deterioration coefficient which quantifies the speed at which deterioration
advances in relative terms can be defined as follows:
=L×M×N
where L: the load coefficient which indicates damaging force due to train load conditions (train speed, passing tonnage, etc.)
M: the structure coefficient which indicates track strength due to differences in the track structure
N: the condition coefficient which indicates the track condition (soil content in the ballast, rail age, rail joint, etc.)
Track deterioration progresses proportionally to the deterioration coefficient.
These coefficients are used to investigate the required level of track structure and the required degree of track maintenance relative to future transport.
2.4 Track Economy
Track strength differs according to a combination of factors involving, for example, rail weight, sleeper type and spacing, and ballast type and thickness. These elements act together to effectively withstand train load and deterioration.
Track strength and the amount of track maintenance work are inversely proportional.
Theoretically, the ideal structure keeps the total of capital outlay for the track structure and maintenance costs such as tamping and material replacement down to a minimum. It would be advisable to classify railway lines into grades according to current and future forecast transport
