Measurement of Maintenance

Last updated on July 10th, 2013 at 10:14 am

“Until you can measure something and express it in numbers, you have only the beginning of understanding” William Thomson [Lord Kelvin (1824-1907)]

Performance of Railway assets depends heavily on maintenance because of the large number of wearing parts where energy is converted from electrical to mechanical or mechanical to mechanical. This makes the maintenance a most challenging job. Measurement of maintenance gives the direction and plays an important role in evolving Maintenance Engineering

For maintenance management, it is very important to know “what is to measure and how to measure?”

In Railways it is measured in terms of

• Availability of asset,
• Reliability,
• Compliance of schedule
• Cost of maintenance.

There are two types of assets directly connected with the functioning of Railways namely fixed asset and another called Rolling assets.

Fixed Infrastructure  : Track, Over Head Equipment, Signaling, passenger amenities at station, Information Technology

Rolling Assets          : Locomotive, Wagon and passenger coaches, Electrical Multiple Units, Tower Wagon

Norms for measurement of maintenance are based on the intensity of services and the impact it makes on the mobility of  train services.

Maintenance Measurement of Rolling Stock- Availability

Availability is the first priority measurement of maintenance. Other measurement starts only after the asset is made available for service. Availability of rolling assets is measured in terms of Statistical and Hourly Availability

Statistical Availability

“An asset is said to be available statistically if it is in use for the day or part of it.”

This index reflects the requirement of major maintenance inputs such as overhauls and major breakdown repairs. This reflects the major maintenance inputs. The target is based on the work content during the major overhauls and the time taken. The challenge before the maintenance engineer is to improve upon the target by reducing the time taken for overhauls and improving reliability and standards of conditioning monitoring of major items avoiding breakdowns.

Target: Statistical Ineffective: EMU/Coaching 12½%     Locomotive 10%

Target for statistical ineffectiveness for EMU/Coaching is more because of the interval between two major schedules that is 18 months requiring approximate withdrawal of asset from service for 21 days. In case of a locomotive,  POH Schedule is after 8 years. Yearly and  Intermediate overhaul is done every 18 and 72 months  but the time taken is only 4-6 days and 12-15 days respectively.

Hourly Availability

Schedule inspection and minor repairs are done during the maintenance time provided in the coaching links at terminals. Therefore, Hourly Ineffective does not have any relevance for rolling stock meant to work for passenger as per defined link. The waiting period in the link is used for schedule inspections and minor repairs.

This definition was added when  Electric and Diesel Loco were introduced in the late 70s as the cost of the asset was high and availability of every hour makes a difference. This index reflects the requirement of minor maintenance inputs such as schedule inspection and minor repairs. For locos earmarked to working coaching trains, this maintenance requirement is built in the coaching links.

Hourly availability is now defined as

“An asset is said to be available on an hourly basis when availability is measured by counting each hour worked by the asset during the period”

Target Hourly Ineffective: 10% on the statistical available locos excluding EMUs/coaches/Coaching locos where hourly maintenance portion is provided in coaching links.

Maintenance Measurement of Fixed Infrastructure

There is no restriction or monitoring when it does not require traffic or power blocks. Redundancy is generally provided in such system so that emergent situation does not arise to cause inconvenience in train running. There is no structured method of measuring it.

• The cost of infrastructure block is very high and is given only by restricting train services during the period.
• Lean period is identified or maintenance blocks designed in the time-table for the purpose called maintenance corridor. Such maintenance corridors were included in the time-table about 10 years ago but lost with the introduction of more and more trains.
• Efforts are always to design infrastructure assets requiring minimum traffic or power block.
• Records of maintenance block demanded and given are maintained.
• There are no targets prescribed for the total duration of traffic and power block for preventive maintenance.

Maintenance Measurement of Rolling Stock-Reliability

Once the asset is made available to provide service, measurement of reliability becomes an issue. The core principle towards measurement of  reliability is the extent to which the  inconvenience is caused in mobility of train.

It is defined as statistical, Non-statistical failure, and other detention as per Manuals.

Statistical Failure

It is defined as

An engine is considered to have failed when it is unable to work its booked train within the prescribed load from start, (i.e. after being attached  to the train), to destination (i.e., to the first shed or point where the engine is booked to cut off or to work another train as per link diagram) or causes a delay in arrival at destination of one hour or more in the case of steam locomotives and 30 minutes or more for passenger trains and 60 minutes or more for freight trains in the case of diesel and electrical locomotives, due to under mentioned causes:

1.  Defective design.
2.  Defective material.
3.  Bad workmanship in shops
4.  Bad workmanship in shed.
5.  Mismanagement by engine crew.
6.  Bad fuel.
7.  Bad water

Non-statistical failures

It is defined as

When a  Locomotive under-going repairs at the end of its trip at a station/terminal yard/shed and not being available for the return trip due to

1. Failure of locomotive booked on trial after heavy schedules or changes of major components like transformer, traction motor, tap changer etc.
2. Failures of the locos which are overdue by more than 24 hours.
3. Cases of heavy time losses (more than 30 minutes) on the run as a result of inclement weather like dust-storms, heavy rains etc. When the visibility of Signals and  slipping of wheels takes place and cannot be attributed to faulty operation of running staff
4. Cases of heavy time losses (more than 30 minutes) due to over-load; load             being more than specified.

Other detentions on locomotive account

Besides above, there are other detentions which are not covered above and classified as other detentions.

Detention  of less than 30 minutes of passenger trains and less than 60 minutes on‘Goods trains and Stallings are classified as other detentions.

Redefining Reliability in the year 2002

It was felt by top management that reliability of all the  assets is not maintained in standard format and there are reporting deviation. In view of this reliability of the asset was re-defined in term of equipment failure vide Railway Board letter No. 2002/E&R/OR/1 dt 14^th Feb 2002. http://www.indianrailways.gov.in/railwayboard/uploads/directorate/eff_res/AssetReliability/Asset%20Failure%20position_1991-92_onwards.pdf.

The sum total of statistical, non-statistical and other cases are now called “equipment failures” which has caused inconvenience in train operation as decided after reconciliation between maintenance and operating man.

This directive of Railway Board takes into account all rolling and fixed assets involved in running of trains.  Data about equipment failures is compiled by Railway Board for all the Railways and there is continuous improvement in the reliability of assets in all spheres of Railway working and is an important factor which led to improvement in Railways performance as whole.

http://www.indianrailways.gov.in/railwayboard/uploads/directorate/eff_res/AssetReliability/Asset%20Failure%20position_1991-92_onwards.pdf

Eleven years have passed since then, and there is some subjectivity cropped in its implementation. Part of the improvement in performance may be due to non-reporting but most of it is the continuous effort in improving designs, manufacturing and maintenance.

Redefining  Reliability in the Year 2009

With the introduction of the Computerized Coaching Information System, it has become simple to monitor the running of trains on minute to basis. This led the Railways taking a  major step of monitoring punctuality loss on a minute-to-minute basis and have given a new dimension to the reliability of the asset. This led to monitoring of reliability on white paper with little scope of manipulation or non-reporting.

Equipment Failure and Punctuality have now become the important indices of measurement of reliability.

Compliance of Schedule

Maintenance Schedule of rolling and fixed aspect involved in train operation is decided by Research Design and Standards Organization. Compliance of schedule is an indication of maintenance discipline. The schedule shall be honored with total respect in words and action. An asset running overdue is an indication of the carelessness of maintenance management.

The maintenance schedule is prepared much in advance depending upon the type of asset varying from one month to one year. A list of assets falling due in the next week or 10 days is circulated to all concerned for monitoring and directing the asset towards the maintenance depot or planning for the maintenance blocks in case of fixed infrastructure.

Emergency withdrawal or power block can be planned but in extreme distress and with all concerned messages.

Cost of Maintenance

What is the optimal maintenance cost of a rolling stock?

There is no standard system defined for working out the maintenance cost of an asset except unit average cost due to very large variables. There is a general myth that more the maintenance cost better is its performance. Maintenance cost is a very good indicator of the quality and reliability of the asset. It is important to assess the maintenance cost accurate to a reasonable extent.

• Divide the maintenance budget of each unit by rolling stock holding and working out average, best and worst unit cost for different maintenance units of Railways.
• There will be variation in maintenance cost of different units. Conduct audit of the best and worst for such large variation. Normalize the average based on factors specific to a particular unit.
• Benchmark the Normalize Average unit cost of a maintenance unit   as a target with a goal to achieve the same.

Maintenance Engineers – remember

• Availability is survival
• Reliability is recognition
• Cost of maintenance is ‘jewel in the crown’

A standard of availability is mostly achieved but the challenge is for reliability and cost of maintenance. This challenge was dynamic, is dynamic and will remain dynamic. Be careful, measurement of maintenance is subjective. Technical honesty is important. Statistical analysis helps in isolation of subjectivity to some extent. Develop measurement techniques to direct you in the right direction based on customer and defect implication.