An optimal track maintenance scheduling model analysis taking the risk of accidents into consideration

• Author: Tatsuo Oyama,Masashi Miwa
• DOI: http://doi.org/10.1111/itor.12425
• Published date: 01 September 2018
• Date: 01 September 2018

Intl. Trans. in Op. Res. 25 (2018) 1465–1490

DOI: 10.1111/itor.12425

INTERNATIONAL

TRANSACTIONS

IN OPERATIONAL

RESEARCH

An optimal track maintenance scheduling model analysis

taking the risk of accidents into consideration

Masashi Miwaaand Tatsuo Oyamab

aTrack Technology Division, Railway Technical ResearchInstitute, Tokyo, Japan

bSchool of Policy Studies, National Graduate Institute for Policy Studies, Tokyo,Japan

E-mail: miwa.masashi.23@rtri.or.jp [Miwa]; oyamat@grips.ac.jp [Oyama]

Received 17 February2016; received in revised form 6 February 2017; accepted 14 April 2017

Abstract

This paper presents an optimal track maintenance scheduling model developed for maintaining adequate

conditions of the railwaytracks and accomplishing an efficient management of the railway service. Our model

has been used in several major Japanese railway companies to develop optimal track maintenance schedules

(OTMS). Since train accidents cause enormous losses (not only for the railway company but also forsociety),

we propose to take into account the risk of train accidents while developing the OTMS. Thus, it is critically

important to identify measures to quantitatively evaluate the risk of accidents to ensure safe and stable

transportation. We propose a method to estimate track maintenance costs and the related costs associated

with the risk of train derailment due to longitudinal level irregularities of the railway track. We attempt to

show a desirable condition of railway tracks by applyingthe accident cost estimation method and the OTMS

model to an actual railwaysection. We also demonstrate how to applythese models to actual railway networks

in general by validating the estimation results using actual numerical data.

Keywords: track irregularity; optimal track maintenance schedule; optimization model analysis; risk of accident; train

derailment

1. Introduction

Over the past decade, the maintenance costs of railways (i.e., tracks, overhead lines, and cars) have

almost consistently accounted for 30–40% of total operating costs (transportation costs), as in-

dicated in Fig. 1. The share of the track maintenance cost exceeded 40% during the same period

(Railway Bureau, 1986–2006). As we cannot expect a large increasein the number of railway users in

the recent depopulating society in Japan, railway companies face the critical challenge of achieving

management efficiency by optimizing these costs in order to provide the same or better transporta-

tion services in the future. The most common fundamental railway structures in Japanare ballasted

tracks, and their maintenance costs are mostly associated with track irregularities. Ballasted tracks

C

2017 The Authors.

International Transactionsin Operational Research C

2017 International Federation of OperationalResearch Societies

Published by John Wiley & Sons Ltd, 9600 Garsington Road, Oxford OX4 2DQ, UK and 350 Main St, Malden, MA02148,

USA.

1466 M. Miwa and T.Oyama / Intl. Trans. in Op. Res. 25 (2018) 1465–1490

40,000

20,000

Fig. 1. Actual maintenance costs and operating costs of railwaysin Japan. [Colour figure can be viewed at

wileyonlinelibrary.com]

Fig. 2. Maintenance work performed for some tracklines with irregularities.

offer excellent workability and economic performance.However, because of the vibrations involved

when trains pass on them, ballasted tracks tend to suffer fromthe formation of irregularities on their

track longitudinal level. The operating safety of trains is diminished if the increaseof such irregular-

ities is left unattended. Maintenance work regarding track irregularities involves the measurement

(geometry inspection) of such irregularities and their subsequent correction and repair.

Typically, maintenance work for track irregularities involves ballast tampering, which is some-

times manually performed with a tie tamper (TT) or using a self-propelledmachine called a multiple

TT (MTT). Figure 2 shows examples of maintenance work performed in some railway lines with

irregularities, in the case of an MTT and a TT, respectively. Most maintenance work is performed

using MTTs, especially in high-speed railway lines and other lines with large traffic volume (passing

tonnage).

Figure 3 shows two examples of the maintenance costs involved with using two MTTs that

are currently employed. The nonoperation costs for these MTTs, for example, the cost necessary

for moving from the former operating site to the next site, is quite negligible compared to other

substantial operation costs, thus it is not considered here. Fixed costs account for nearly 50% of the

total maintenance cost as seen in Fig. 3. Regarding the variable costs, the fuel cost for using MTTs,

and the cost for supply goods are higher than the labor cost.

C

2017 The Authors.

International Transactionsin Operational Research C

2017 International Federation of OperationalResearch Societies