Railway Waterway Maintenance

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Questions and Answers

What is the purpose of providing weep holes in abutments, wing walls, and return walls?

To prevent undermining or scour of the substructure

To avoid build-up of hydrostatic pressure (correct)

To prevent weathering of mortar

To reduce leaning or bulging of walls

What should be checked and maintained according to paragraph 17?

Boundary pillars on each bank of a river

Granular backfill material

Obstructions in waterways within railway limits (correct)

Filter layers behind the masonry

What is the recommended interval for providing weep holes in both horizontal and vertical directions?

1m (correct)

1.5m

0.5m

What is the purpose of providing a filter layer behind the masonry?

To prevent expansive soil like black cotton soil from affecting the structure Signup and view all the answers

What should be done to tackle undermining or scour of the substructure?

Refer to paragraphs 204 and 513 Signup and view all the answers

What should be avoided in the backfill material used behind the masonry?

Expansive soil like black cotton soil Signup and view all the answers

What is the recommended location for the bottom-most row of weep holes in case of flowing streams?

Above low water level Signup and view all the answers

What is the purpose of providing marginal bunds, guide bunds, and spurs/groynes?

To control waterways Signup and view all the answers

What is the recommended air pressure for opening of the tools?

5.6 to 7 kg/cm2 Signup and view all the answers

What should be the temperature of the rivet before driving?

White heat with sparks flying off Signup and view all the answers

Why is it important to put the whole weight of the body behind the hammer?

To prevent the hammer from bouncing Signup and view all the answers

What type of rivets should be used according to IRS specifications?

Rivets conforming to IRS specifications Signup and view all the answers

When should renewal of slack rivets be taken up in end stiffeners?

When 30% of rivets are hammer loose Signup and view all the answers

Why should the rivet be driven straight while hot?

To ensure the rivet head is formed correctly Signup and view all the answers

What should be done with hammer loose rivets in flange splices?

Replace all rivets on that side of the splice location Signup and view all the answers

When is it not necessary to renew rivets, though they are hammer loose?

In the lap or butt joints of trough flooring Signup and view all the answers

Where should HSFG bolts not be painted?

At main angle to web connections Signup and view all the answers

What is the maximum length of the welding tack applied to the bolt projection beyond the nut?

5 mm Signup and view all the answers

What is the general term for the chemical combination of steel with oxygen?

Rust Signup and view all the answers

What is the term for corrosion limited to an extremely minute area?

Pitting Signup and view all the answers

What is an alternative to applying welding tack to the bolt projection beyond the nut?

Applying proven bonding agent Signup and view all the answers

What is the purpose of applying welding tack to the bolt projection beyond the nut?

To prevent theft/sabotage Signup and view all the answers

What is the term for the deterioriation of metal due to its interaction with the corroding environment?

Corrosion Signup and view all the answers

What is one of the means of preventing corrosion?

Painting Signup and view all the answers

What should be done to a new brush before using it for painting?

Soak it in raw linseed oil for at least 24 hours Signup and view all the answers

How should the brush be held when applying paint?

At a 45-degree angle to the surface Signup and view all the answers

What should be done to the paint drum contents before application?

Mix it thoroughly by pouring or mechanical mixing Signup and view all the answers

What should be avoided when applying paint?

Using rags, waste cotton, or cloth for application Signup and view all the answers

What is the maximum time lag between surface preparation and the application of primer coat?

24 hours Signup and view all the answers

How should the paint be applied to achieve uniform coverage?

With several light vertical and lateral strokes Signup and view all the answers

What is the factor that determines the periodicity of painting in floor systems of girders?

Chief Engineer's specification Signup and view all the answers

What is the purpose of patch painting in floor systems of girders?

To repair small areas of paint that show pronounced deterioration Signup and view all the answers

What should be done to the paint after application?

Left to dry till it sufficiently hardens Signup and view all the answers

What should be ensured while applying the coat of paint?

The coat is uniform and free from defects Signup and view all the answers

Which of the following locations may require patch painting?

All of the above, including top flanges of plate girders and deck systems Signup and view all the answers

What is the recommended surface preparation for metallising?

Grit/sand blasting Signup and view all the answers

What is the purpose of metallising and epoxy-based paints?

To provide a protective coating in corrosive environments Signup and view all the answers

What happens to the base metal in metallising?

It is unaffected by the atmospheric action Signup and view all the answers

What should be done to the affected top coat if it has failed?

It should be wire brushed thoroughly and required number of finishing coats applied Signup and view all the answers

What is the recommended interval for periodic painting in arid zones?

Six years Signup and view all the answers

What is the primary purpose of using a relatively dry mixture in shotcrete or guniting?

To support the mixture itself without sagging or sloughing Signup and view all the answers

What is the minimum capacity of the air compressor required for shotcrete or guniting?

10 cum/min Signup and view all the answers

What is the maximum nominal size of the coarse aggregate used in shotcrete or guniting?

12.5 mm Signup and view all the answers

What is the purpose of using reinforcement in shotcrete or guniting?

To provide additional support to the structure Signup and view all the answers

What is the recommended type of cement to be used in shotcrete or guniting?

Ordinary Portland cement Signup and view all the answers

What is the purpose of using a placing nozzle with hose in shotcrete or guniting?

To direct the mixture to the desired location Signup and view all the answers

What should be done immediately after use of the grease gun syringe?

It should be washed with acetone Signup and view all the answers

Why should direct skin contact be avoided when handling shotcrete or guniting materials?

To prevent skin irritation Signup and view all the answers

What is the purpose of drilling holes in a staggered manner at 500 to 750mm spacing in both directions?

To cover the entire area proposed to be grouted Signup and view all the answers

What is the purpose of sealing the cracks and annular space around G.I. pipes with rich cement mortar?

To prevent water from entering the structure Signup and view all the answers

What is the purpose of sluicing the grout holes with water a day before grouting?

To saturate the masonry Signup and view all the answers

What is the recommended duration for curing after grouting?

14 days Signup and view all the answers

What is the purpose of providing tell tales in grouting?

To check the effectiveness of grouting Signup and view all the answers

What is the composition of epoxy grout?

Epoxy resin, hardener, and thinner Signup and view all the answers

What is the purpose of using suitable fillers in epoxy grouting?

To fill wide cracks and voids Signup and view all the answers

What is the recommended time limit for using the material for preparing grout?

15 minutes Signup and view all the answers

Where should the date of painting of steel work be painted in white?

On the outside of the left girder of the first span Signup and view all the answers

Where should the highest flood level line be painted, for bridges over 60 meters in length?

On each of the abutments on the downstream side Signup and view all the answers

What should be provided on abutments or on piers of the end spans for important bridges?

Flood level gauges Signup and view all the answers

Where should the direction of flow be distinctly marked in white?

On the abutment or pier Signup and view all the answers

Where should plaques showing particulars of foundations be fixed?

Over every abutment and pier Signup and view all the answers

Where should name boards be fixed at important bridges?

At either approach, at a distance of about 15 meters from the abutment Signup and view all the answers

How should the Full Supply Level be marked at all Canal crossings?

By a 25mm broad white line along with the year of its occurrence Signup and view all the answers

What is the primary reason why the presence of rust under the paint film can cause its failure?

Rust weakens the adhesion of the paint film to the surface Signup and view all the answers

In which color should the Danger level be distinctly marked in all the bridges?

Red Signup and view all the answers

What is the minimum requirement for a surface prepared for painting?

It should be free from contaminants and rough enough for adhesion Signup and view all the answers

What is the most effective method of surface preparation mentioned in the content?

Blast cleaning (sand or grit blasting) Signup and view all the answers

What is the purpose of flame cleaning?

To remove rust and mill scale Signup and view all the answers

What is the result of not removing rust, oil, grease, and dirt from the surface before painting?

The paint film will not adhere to the surface Signup and view all the answers

What is the purpose of using emery paper, wire brushes, and scrapers in surface preparation?

To clean the surface during normal maintenance Signup and view all the answers

What is the result of using power driven tools for surface preparation?

Oil and grease are removed, and heavy scale and rust are removed by hand tools Signup and view all the answers

What is the purpose of blast cleaning (sand or grit blasting)?

To remove rust, mill scale, and old paints along with some of the base metal Signup and view all the answers

What is the primary reason for applying grease graphite to bearings?

To reduce corrosion and provide smooth surface Signup and view all the answers

What is the recommended interval for inspecting roller bearings with oil bath?

At least once in 5 years Signup and view all the answers

What is the purpose of providing dust covers for roller bearings with oil bath?

To keep the oil free from dirt Signup and view all the answers

What is the recommended placement of the tooth bar of the roller assembly?

Vertically at mean temperature Signup and view all the answers

What is the characteristic of elastomeric bearings in terms of volume change and shear?

Very stiff in resisting volume change and flexible in shear Signup and view all the answers

What is the purpose of indicating the maximum expansion and range of temperature in the completion drawings of bridge stress sheet?

To determine the slant at the time of greasing Signup and view all the answers

What is the reason for jamming the space between girders with wedges during lifting of fixed ends?

To prevent longitudinal movement of the girders Signup and view all the answers

What is the characteristic of phosphor bronze bearings?

They are corrosion-resistant and retain a smooth surface Signup and view all the answers

Study Notes

Protective Works for Waterways

Guide bunds, marginal bunds, and spurs/groynes are provided to control waterways
These works are implemented singly or in combination to achieve effective control

Maintenance of Waterways

Obstructions in waterways should be cleared away on both sides of the line within railway limits for the full extent of the waterway
Boundary pillars on each bank of a river or important waterway shall be erected to prevent and control encroachments

Maintenance of Substructure

Abutments, Piers, Wing Walls, and Return Walls

Weathering, leaching of mortar, and leaning/bulging of abutments, wing walls, and return walls can occur
To avoid build-up of hydrostatic pressure:
- Weep holes should be provided at 1m intervals in both horizontal and vertical directions
- Adequacy of existing weep holes should be checked and additional weep holes provided if required
- Choked weep holes should be cleaned and made functional
- Backfill material should be granular and not contain expansive soil like black cotton soil
- Proper filter layer should be provided behind the masonry
Excessive earth pressure can be taken care of by providing masonry or cement concrete buttress
Undermining/scour and other rehabilitation problems can be tackled by referring to paras 204 and 513

Cracks in Masonry/Concrete

Rivets should be heated almost to white heat and to a point when sparks are just beginning to fly off
Rivets should be driven and the snap removed within 20 seconds of the rivet leaving the fire
Rivets should be driven straight, while hot, keeping the hammer coaxial
Rivetter should have his staging at a height which enables him to put the whole weight of his body behind the hammer
Rivets conforming to IRS specifications only should be used
Adequate air pressure of 5.6 to 7 kg/cm2 should be ensured for opening of the tools
In the case of long bridges, the air compressor may be centrally located at a suitable trolley refuge, with main pipeline running in both directions with suitable tappings

Replacement of Loose Rivets in Plate Girders

Renewal of slack rivets should be taken up for:
- All rivets which are hand loose or which have lost 50% of their head by corrosion
- All hammer loose rivets where corrosion has set in between the head and the plate
- In end stiffeners when the percentage of hammer loose rivets is >30%
- In flange splices when the number of hammer and hand loose rivets is 30% or more of the total rivets on any side of the splice location
- All hammer loose rivets at main angle to web connection up to 1/12 span from either support of the girder
- When loose rivets in end connections of lateral and cross bracings of plate girder spans require renewal, all the rivets in the end connections should be renewed

Maintenance of HSFG Bolts

HSFG bolts should be painted as per normal painting schedules and painting methodologies as specified in the Indian Railways Bridge Manual for the girder as a whole
Anti-theft and anti-sabotage measures:
- Bolt threads may be destroyed by applying welding tack to the bolt projection beyond the nut after final tightening and inspection
- Alternatively, proven bonding agent may be applied to the threads projecting beyond the nut to seize or lock the bolt in position

Corrosion and its Prevention

Corrosion is deterioration of metal due to its interaction with the corroding environment
Corrosion may take place in either uniform or local forms
Prevention of corrosion:
- Protective coatings by painting
- Metallising - a form of protection by spraying a metal either zinc or Aluminium

Metallising and Epoxy Based Paints

Metallising:
- In metallised protection, base metal like zinc or aluminium is lost by atmospheric action, while the base metal (steel) remains unaffected
- Zinc or aluminium can be sprayed on the surface prepared by grit/sand blasting for giving such protection
Epoxy based paints:
- For locations where girders are exposed to corrosive environments, protective coating by way of metallising or by painting with epoxy-based paints may be applied

Painting of Bridges

The date of painting of steel work should be painted in white on the outside of the left girder of the first span.
For important girder bridges, the left girder at each end should bear the date of painting.
The highest flood level line should be painted distinctly by a 25mm broad white line along with the year of its occurrence, in figures 100mm deep.
The direction of flow should be distinctly marked in white on an abutment or pier.
Name boards at important bridges should be fixed at either approach at a distance of about 15 metres from the abutment indicating the name of the river and the number and length of spans.

Maintenance of Foundations

A bridge foundation having less than 2M depth below bed level in case of arch bridges and 1.2M depth below bed level in case of other bridges is termed as shallow foundation.
Procedure for cement grouting involves drilling holes in the structure, fixing G.I. pipe pieces, sealing cracks and annular space, sluicing with water, injecting cement grout, curing, and providing tell tales.
Grouting equipment must be cleaned thoroughly after use.

Epoxy Grouting

Epoxy grout consists of an epoxy resin and a hardener which react chemically when mixed.
Epoxy resins are thermosetting and can be varied to suit all types of conditions.
Manufacturer's detailed instructions should be followed for safe handling and processing of epoxy grout.
Direct skin contact should be avoided, and hand gloves and protective goggles should be used.

Shot Creting / Guniting

Shotcrete is mortar or concrete conveyed through a hose and pneumatically impinged at high velocity on to the surface to be treated.
Shotcrete is suitable for repairing spalled concrete surface as well as for strengthening weathered stone or brick masonry.
Equipment required for shot creting includes a guniting machine, air compressor, placing nozzle with hose, and materials such as ordinary Portland cement, sand, coarse aggregate, water, and admixture.

Protective Coatings by Painting

Correct surface preparation of the steel to receive the paint is the single most important factor in ensuring good performance.
Surface preparation methods include manual hand cleaning, cleaning with power driven tools, blast cleaning, and flame cleaning.
The surface should be clean, dry, and free from contaminants, and rough enough to ensure adhesion of the paint film.

Bridge Bearings

Phosphor bronze bearings need not be greased as they are corrosion-resistant and retain the smooth surface.
The tooth bar of the roller assembly should be placed vertically at mean temperature.
In the case of roller bearings with oil bath, dust covers should be provided to keep the oil free from dirt.
Inspection of the bearings, after removal of the casings to the extent necessary, should be carried out at least once in 5 years.

Elastomeric Bearings

Elastomeric bearings are made of natural or synthetic rubber of shore hardness of approximately 50 to 70.
They are very stiff in resisting volume change but are very flexible when subjected to shear or pure uniaxial tension.
They are generally reinforced with steel plates in alternate layers to reduce bulging.

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Description

This quiz covers the measures taken to maintain waterways within railway limits, including clearing obstructions, guide bunds, and boundary pillars.