Various cost-effective maintenance practices for conventional track structures

Written by Avinash Prasad, P.E., L.S., Metropolitan Transportation Authority - New York City Transit
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Use determines a given maintenance strategy, but planning determines that strategy's cost effectiveness.

 

{besps}April16_Challenges{/besps} {besps_c}0|1challenges.jpg| A diagram of a typical ballasted track section.{/besps_c} {besps_c}0|2challenges.jpg| Automatic tamping machine of track and turnouts. In this image, the machine is a Plasser & Theurer UNIMAT 08 – 475/4S.{/besps_c} {besps_c}0|3challenges.jpg| An example of typical light maintenance of the track structure.{/besps_c}

Use determines a given maintenance strategy, but planning determines that strategy’s cost effectiveness.

This article addresses conventional railroad systems throughout the world. It mentions the key points highlighting cost-effective maintenance strategies of permanent way components. Track has been termed the permanent way.1 The permanent way components of the track are rails, crosstie (sleepers), fasteners, ballast, sub ballast and soil formation.

There are ballasted, as well as non-ballasted track structures. Both types of track structures have their own advantages and disadvantages. Normally, the installation cost of non-ballasted track structures is more than that of ballasted track structures, whereas the maintenance cost of non-ballasted track structures is less than that of ballasted track structure.

A turnout is defined as an arrangement of a switch and a frog connected by closure rails, by means of which rolling stock may be diverted among different tracks.3 A turnout could produce high lateral forces and accelerations, which require slower operating speeds and can have adverse effects on ride quality and component life.3

The maintenance of a conventional track structure should be such that it should follow, or tends to follow, the requirements of an ideal permanent way.4 There are various requirements that an ideal permanent way should possess, e.g. the gauge should be uniform and correct, both rails should be at the same level in straight track and at proper super elevation in a curved track; the permanent way should be properly designed so that the load of the train is uniformly distributed over the two rails, the fasteners and the ties; the track should have enough lateral strength; the curve radii and super elevation should be properly designed for the intended operating speed and prescribed uncompensated centrifugal acceleration; the track must have a certain amount of elasticity; all joints, points and crossings should be properly designed and offer a degree of robustness. The drainage system of the permanent way should be as perfect as possible and, in summary, all the components of the permanent way should satisfy the design requirements and should have adequate provision for easy renewals and repairs.

Track needs regular maintenance to remain in good order, especially when high-speed train operations are involved. Improper maintenance will impose speed restriction along the affected track route to avoid accidents. In the past, track maintenance was purely performed using manual labor. At that time, trackmen used to fix irregularities in horizontal alignment (using lining bars) and vertical alignment (using tamping jacks) of the track structure. During the course of time, maintenance of track was facilitated by use of a variety of specialized machines, such as the ballast cleaning machine (BCM), Universal Tamping Machine (UTM), etc. Nowadays, maintenance of track structure is more mechanized compared to earlier times. Mechanized maintenance has obvious advantages when compared to manual maintenance.

The railroad companies should not wait to do emergency restoration work after an accident due to track maintenance failure. Rather, they should perform routine and special inspections of permanent way components on a regular basis and perform necessary manual, as well as mechanized maintenance. Maintenance should be followed by inspection of the permanent way. The various types of inspections used to inspect the conventional track structure (particularly in Indian Railway) are inspection by foot, push trolley inspection, motor trolley inspection, foot plate (engine) inspection and rear vehicle inspection.

The author would like to mention the most common manual maintenance practice followed in most of the Asian countries.2 The manual permanent way maintenance is largely done by gangs consisting of gangmen under the supervision of a gangmate. The most common system of routine manual (non-mechanized) track maintenance is known as through packing. This includes the following steps:

  • Opening of ballast and loosening of rail fittings;
  • Examination of track and squaring of sleepers (ties);
  • Gauging, sleeper (ties) packing and re-packing of joint sleepers (ties);
  • Boxing the ballast section and clean-up.

The author would also like to mention the need for a low-cost maintenance strategy of existing turnouts.

“Points and crossings are vital and the most weak part of the track structure, which requires baby care otherwise in time it will lead to many accidents/interruptions to normal traffic, if not maintained properly,”2 N.R. Kale et al., wrote in their research on points and crossings maintenance on Indian Railways.

The following strategy is based on the author’s 2011 AREMA Conference paper “Higher Diverging Speed Turnout Design in the Same Footprint.” Special trackwork, including turnouts, can reduce a track section’s capacity by requiring speed restrictions in order to extend the turnout’s service life and can be an expensive component to replace once that its service life ends. Modifying a rail system’s existing turnouts to be able to handle higher diverging speeds could increase line capacity and improve the dynamics and mobility of the system. A hypothesis developed by the author was presented at the AREMA 2011 Annual Conference in conjunction with Railway Interchange 2011 and proposes the possibility that developing low-cost upgrades to a system’s turnouts for higher diverging speeds may result in lower life-cycle costs and increased capacity by reducing lateral forces and acceleration, as well as component wear.3

The railroad industry spends hundreds of millions of dollars every year on railroad track maintenance activities, routing large crews and heavy machinery throughout its extensive railroad networks. Effective planning saves on maintenance costs and resources and affects the safety and operational efficiency of the maintenance activities.8
The author would like to emphasize the need of proper planning in maintenance activities to achieve better operational efficiency, less maintenance cost and aiming for zero accidents. Railroad companies are advised to start with basic manual/mechanized maintenance practices and then go for more sophisticated maintenance practices to achieve better operational efficiency, less maintenance cost and aim for zero accidents.

Future work
With an increasing pace of changes in technology and the current economic downturn, organizations around the world are focused on more cost-effective and value-added technology related to the maintenance practices of conventional track structures and associated infrastructures. The author continues with his research on various cost-effective maintenance practices for conventional track structure. Operations research techniques offer opportunities to facilitate and improve the decision-making process. One of his thoughts includes the use of the Operation Research Principles for dealing with various cost-effective maintenance practices for conventional track structure. The author will provide a more in-depth look at this subject at the American Railway Engineering and Maintenance-of-Way Association (AREMA) 2016 Annual Conference & Exposition, Aug. 28-31 in Orlando, Fla.

Acknowledgement
The author acknowledges the help of Ms. Purnima and Prayaga Prasad in peer reviewing this article. The author sincerely thanks his professors at New York University and supervisors at Metropolitan Transportation Authority-New York City Transit for their help and encouragement.

References
1. Hay, W.W. Railroad Engineering. New York: Wiley, 1982. Print.
2. India. Indian Railways. N.p.: n.p., n.d. Indian Railways. Indian Railways. Web. 13 Mar. 2016.
3. Prasad. A. “Turnout Design: Higher Diverging Speed in The Same Footprint.” Paper presented at 2011 Annual AREMA Conference, Minneapolis, Minn., Sept. 18-21, 2011.
4. Rahul, B. G. Component Parts of a Permanent Way (n.d.): 1-26. Web. 13 Mar. 2016.
5. “Transportation Engineering II (CVL 007).” Introduction to Railway Engineering (T.E 2). N.p., 23 Mar. 2015. Web. 23 Mar. 2016.
6. Skanska. “Rail Mechanization.” Rail Mechanization-Product & Services-Skanska. N.p., 11 Aug. 2014. Web. 22 Mar. 2016.
7. Spall, N. “Rail Industry Focus. Significant Civil Engineering at Farnworth Tunnel Nears Completion.” Rail Technology Magazine, 28 Dec. 2015. Web. 13 Mar. 2016.
8. Ouyang, Y. “Improving Railroad Track Maintenance Scheduling with Operations Research Techniques.” TR News. Issue Number 286, pp. 55-56.

Disclaimer
Even though the author works for MTA-NYCT, any opinions, findings and conclusions or recommendations expressed in this material does not reflect the views or policies of MTA-NYCT nor does mention of trade names, commercial product or organizations imply endorsement by MTA-NYCT. MTA-NYCT assumes no liability for the content or the use of the materials contained in this document. The author makes no warranties and/or representation regarding the correctness, accuracy and or reliability of the content and/or other material in the paper. The contents of this file are provided on an “as is” basis and without warranties of any kind, are either expressed or implied.

About the author
Avinash Prasad works for MTA-NYCT as a civil engineer level–III. He has had more than 27 years of professional experience mostly with MTA-NYCT and foreign railways. Being a professional in the United States and foreign railroad companies in various capacities (employee/consultant), the author has extensive experience of various maintenance practices for conventional track structures. He is a registered professional engineer and land surveyor in multiple states and a Doctor of Philosophy Candidate at New York University. The author is member of AREMA since 2000 and a committee member of Rail (2007-2011), Track (2007-present) and High Speed Rail Systems (2011-present). His technical papers were presented at earlier AREMA conferences and published in Railway Track & Structures magazine.

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