Artical : TRACK MAINTENANCE AND CONSTRUCTION

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:CONSTRUCTION OF RAILWAY TRACKS:

TRACK MAINTENANCE AND RENEWAL
Track maintenance means the total process of maintenance and renewal required to ensure that the track meets safety and quality standards at minimum cost. Annual maintenance on the NS network, with its 4500km of main line tracks, comprises renewal of roughly 140 km of main line, 40km of secondary tracks and sidings, 1000 km of mechanical tamping, 60km of ballast cleaning , 10 km of corrective grinding and renewal of 250 switches. In addition to this track requires spot maintenance on a daily basis.
Factors that influence maintenance costs include the following:
Following are the factors which the maintenance of tracks.

•  Track maintenance activities—listed and defined,
•  Labour and material costs,
•  Work windows,
•  Track inspection and maintenance policies,
•  Operating characteristics,
•  Budgeting and accounting practices,
•  Availability of capital and operating funds, and
•  Record keeping procedures.

Track maintenance, in the broadest sense, is a product of resources, judgments, experience, skills, tools, and policies that are exercised in a range of service environments and within every conceivable type of organizational structure.


Track maintenance definitions and understandings are as follows:
1.  Track
2.  Maintenance demand
3.  “Acceptable” track conditions
4.  General maintenance approaches
5.  Life-cycle costs
6.  Direct and indirect costs
7.  Light rail, heavy rail
Track
Track is the system of materials from the subgrade to top of rail in ballasted track or from the bottom of a rail support device (fastener, block tie) to the top of rail in ballast-less track.

Maintenance Demand
Maintenance demand is the level of effort, materials, and equipment to provide acceptable track.
Acceptable Track Conditions
Acceptable track conditions are as defined by APTA and American Railway Engineering and
Maintenance-of-Way Association (AREMA) track safety standards. Track is properly maintained or “acceptable” when the track condition is acceptable for the designed operating parameters over that track.
Any length of track that meets the applicable standards for the designed operation on that track is considered to be “acceptable.” Any flaw in the track that causes it not to comply with the track standards for the designed operation is an unacceptable track condition.
General Maintenance Approaches
The execution of track maintenance varies by maintenance philosophies or budget realities. Approaches to track maintenance range from preventive maintenance, where developing conditions are corrected as they occur, and crisis maintenance, where corrections occur at failure (service degradation by slow order for a track condition is, by the foregoing definition, a failure), as well as “spot” or “programmed” maintenance. Most if not all maintenance practitioners adhere to preventive maintenance as a goal,although budget constraints require a balanced approach somewhere between ideal maintenance and crisis maintenance.
Life-Cycle Costs
Life-cycle costs are the sum of all costs of a specified track throughout its economic life, from first installation through removal or replacement. These costs include the material purchase and initial track construction, routine track inspections, and periodic maintenance to the end of its economic life, as well as disposal or recycle costs; for example, tie disposal, disposal of spikes and anchors, and including costs to collect and sell to scrap dealers. The nature of track requires the definition of life cycle to be stated for an arbitrary period, often assumed to be on the order of 25 years, within which the all the track performance cross-influences are adequately captured. Economic life is defined as a point in time where the trend of annual maintenance costs of an existing component or system of components exceeds a threshold value. Technically, a threshold value for identifying useful economic life is when repair costs have reached some percentage of the replacement and future maintenance costs. A key criterion for economic life is track that meets the definition of acceptable track conditions, described previously. Track with deferred maintenance requires “temporary” slow orders in place until repairs or maintenance is performed are one level, whereas “slow orders” to continue service occur when track has exceeded its economic life.
Direct and Indirect Maintenance Costs
The definitions of direct maintenance effort and the supporting organizational effort/cost to implement productive maintenance are fundamental for this project. For this report, direct maintenance is an effort to perform a specific maintenance task, such as replacing a frog or a rail. The effort and costs of direct maintenance are defined as those functions directly involved in the maintenance task that should be common to all rail applications.
For this report only, the following are direct maintenance efforts/costs for specific maintenance tasks:
•  Labor and material to perform a task. This does notinclude the effort to assemble crews, material, and equipment; travel to a site; or management overheads. Labor for direct maintenance includes all craftsmen (track laborers, welders, machine operators, and any helpers) and their direct supervision (the crew foremen for most organizations). Material costs are the direct cost of components, including delivery of the material to the receiving point in the system;
•  Expendables (fuel, etc.);
•  Track inspection and reporting;
•  Employee fringe benefits; and
•  Premiums for constraints such as working in tunnels or other constricted areas, at night, etc.
Indirect maintenance efforts are the costs of preparing crews and materials for a task, travel from a staging area to a site, delays for example resulting from limited track access, mid-level supervision, material stores costs (material stock-pile efforts,including purchasing activities, inventory, etc.), equipment procurement and maintenance, clothing allowances, training, and organization overheads that are not captured in the direct costs or other category.
Heavy Rail, Light Rail
A heavy rail system usually has an exclusive right-of-way (ROW) with no other intervening transportation form, including road crossings. A lightrail system shares the ROW in some manner with other transportation forms, largely road crossings and in-street operation. The term light rail, despite its implications, has nothing to do with weight. The vehicles and track for light rail have weights similar to heavy rail configurations. Hearsay suggests that the term “light rail” was devised as a political euphemism for streetcars and trolleys to allow funding consideration over objections that the latter were considered obsolete. Both modes may be operated in transit commuter services that shape ROW with freight railroads.
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