INSPECTION OF BRIDGES

Bridges are key elements in the road network, because of their strategic location and of the unfavourable consequences when they fail or when their capacity is impared. The neglect of unslightly, deteriorating or damaged bridges may not only affect safety of public but also the public confidence and subject the responsible P.W.D. Officers to severe criticism. Particular attention must therefore be given to the systematic inspection of bridges, for the assurance of safety and for protection of capital invested in the bridge structure by timely and economic planning of the preventive maintenance and repair work.

The Government in P. W.D. have already pres cribed a procedure for inspection and recording of inspection notes for bridges in the form the masonry register, Accordingly, Executive Engineers and Deputy Engineers are responsible for inspection of major bridges and minor bridges including culverts respectively in their jurisdiction twice a year i.e. once immediately before monsoon and once immediately after monsoon. It is observed that several bridges even including some long span bridges constructed in the last two decades and exposed to severe environments have deteriorated much faster than anticipated and that quite a number of bridges which have been constructed and are being constructed with new techniques require close monitoring. It has, therefore, there is need of reviewing the procedure of inspection, responsiblities of Officers and periodicity of inspection of bridges. The following instructions are issued to field officers on the subject of inspection of bridges. These instructions shall also apply to road over bridges, viaducts, subways and flyovers.

(A) The bridges and C.D. works will be classified, for this purpose, into categories depending on the linear waterway and environment or conditions of exposure of the bridge or C.D.work. The conditions of exposure are defined in I.R.C. 

Classification of bridges :

a. Culverts with length between abutment faces upto 6 m.

b. Minor bridges with length between abutment faces less than 30 m. but more then 6 m.

c. Major bridges with length between the abut- ment faces 30 m, or more but less than 250 m.

Exposed to - 

i) Severe environment and

ii) moderate environment.

d. Long bridges with length-between the abutment faces of 250 m. or more 

Exposed to - 

i) Severe environment and 

ii) moderate environment.

By Government circular, It is the responsibility of Chief Engineer in charge to classify the environment for the bridge. 

(B) Three types of inspections as below shall be necessary :-

(1) Routine Inspection. 

Routine inspection shall be carried out periodically as per frequency indicated in Appendix A. The purpose is to report the fairly obvious deficiencies which might lead to traffic accidents or cause high maintenance and repairs costs if not treated promptly. Routine inspection will have to rely mainly on visual assessment using conventional standard tools and methods. Each officer responsible for inspection shall prepare a calender of inspection for bridges in his jurisdiction to obtain periodicity of inspections as prescribed in Table below.

 

Class of Bridge	Inspecting Oficer	Frequency
1. Culverts and C.D.work	J.E.	Twice a year (Pre-monsoon and Post-monsoon)
	D.E.	Once a year (Pre-monsoon).
2. Minor Bridges.	J.E.	Twice a year (Pre-monsoon and Post-monsoon)
	D.E.	Twice a year (Pre-monsoon and Post-monsoon)
3. Major Bridges.	D.E.	Twice a year (Pre-monsoon and Post-monsoon)
	E.E.	Twice a year (Pre-monsoon and Post-monsoon)
4. Long bridges (exposed to moderate and severe environments).	E.E.	Twice a year (Pre-monsoon and Post-monsoon)
	S.E.	Once a year (Pre-monsoon).

(2) Comprehensive Inspection. 

This is a more intensive and detailed inspection. This will involve close examination of elements of the structure. It will be primarily a closer visual. assessment supplemented by standard instrumented aids. A comprehensive inspection becomes necessary six months after completion of the bridge and later the minimum frequency of this type of inspection shall be as per table below. More frequent inspections will be essen- tial if the routine inspection reveals any distress in the bridge structure. The inspection shall be done by Senior Engineers against a comprehensive check list of items related to the form, material, condition and situa- tion of the structure. Such a check list will be found as Appendix C of this Circular, A calender also for com prehensive inspection of bridges shall be prepared by each officer responsible for such inspections to obtain the periodicity as per table below.

 

Class of Bridge	Inspecting Oficer	Frequency
1.Minor bridges and slab drains	E.E.	Once in 5 years
2. Major bridges in moderate environments	S.E.	Once in 5 years
3. Major bridges in severe environments	S.E.	Once in 3 years
4. Long bridges in moderate environments	C.E.	Once in 5 years
5. Long bridges in severe environments	C.E.	Once in 3 years

(3) Special Inspection. 

This shall be undertaken in the event of unusual occurrences such as earthquake, accidents, passage of unusual loads or floods, major weaknesses noticed during routine or comprehensive inspection. Such inspections may require a good deal of supplementary testing and structural analysis and will invariably require detailed involvement of Designs Organisation of the Department and experts in the relevant field. A detailed report with photographs shall be prepared for each bridge.

(C) Means of Access.

Appropriate means of access are a prerequisite for all three forms of inspection. For every means of access special emphasis shall be laid on: safety, ease and convenience, Superintending Engineer, Designs (Bridges) as well as superintending Engineers in charge of maintenance of bridges are called upon to give due consideration right at the design stage to the provision of proper means of access taking into account the individual requirements of the structure and its components such as type of structure, topographical, local and climatic conditions of the bridge site, height minimum water level, possible clearances, safety etc. 

The possible means of access can be of the following type: 

1. Built-in access.

II. Semi-mobile access. 

    i) access ladders.

    ii) manholes. 

    iii) hand-rails. 

    iv) catwalks.

    v) Platforms.

    vi Inspection pits.

    vii) Provision for setting up flanking, scaffolding etc. 

    viii) Fixtures and provisions for operation of semi-stationery inspection equipment.

III. Mobile Equipment.

    i) Equipment operating under the bridge (tra vellers) from the ground, boat/barges. 

    ii) Equipment operating from the bridge deck (snonpers).

Provision should be made for power supply for connection of lamps, tools or other electrically operated type of equipment. The Chief Engineer shall be responsible for providing the appropriate types of mobile equipment in sufficient number to the inspecting personnel depending on the type and importance of structure, Occassionally there may be a need for inspection of parts of substructure or founda tions under water. The inspecting personnel can utilise the services of special equipment and divers in such cases. Where necessary and possible drone cameras with remote control could be employed.

D. Assessment Techniques and Equipment. 

These should be considered as an integral part of bridge inspection. They should be selected in relation to the number and types of bridges to be inspected, the personnel available with appropriate standard of professional training and level of inspection.

In a very general way routine inspection will be try visual assessment using conventional standard tools listed as below. Comprehensive inspection will also have to rely primarily on visual assessment but will be supported by more advanced tools and methods. Special inspection may require rather advanced techniques and equipment apart from visual assessment.

Standard Tool

- Clip boards, chalk, narkers, clamps etc. Pocket tapes, folding rules, tapes (10 m. to 50 m.) feeler, gauges, callipers.

- Straight edge, plumb bob, protractor, level.

- Thermometers.

- Inspection mirror, binoculars, magnifying glass, camera, flash light. 

- Pocket knife, wire brush.

- Chipping hammer..

- Thin steel rod for use as probe (8 to 10 m. diameter) crack meter.

Possible instrument aided assessment methods (only indicative) 

 

Assessment of	Inspecting Oficer	Possible method
Concrete	Strength	Schmidt Rebound Hammer
	Quality	Ultrasonic Pulse velocity
	Lamination	Sounding
	Cover	Profometer
Steel	Cracks	Ultrasonic Pulse velocity
	Cable/ Wire failure	Radiographic
	Corrosion	Electrical half cell potential, Electrical Resistivity meter
Global behaviour movements		Surveying Instruments, Dial guages, Strain guages
Extensometric measurement forces		Strain guages and Extensometers
Extensometric measurement Pressures		Pressure trannsducers or load cells
Miscellaneous	Thickness of Coatings	Paint film guage
	Waterproffing membranes	Electrical resistance
	Vibrations	Accelerometer

The Chief Engineer in charge with the advice of Superintending Engineer, Designs (Bridges) shall decide on hiring or purchasing of the special equipment.

E. Documentation.

Three documents are most essential for bridge inspection operation.

1. A bridge register to give list of bridges with name of river, location etc. in the Division. 

2. Original bridge report which is prepared on the basis of completion drawings alongwith salient design, assumptions and details supplemented whever necessary by site inspection.

3. Inspection report.

The proforma for documents (1) and (2) shall be as given in the I.R.C. Special Publication 18 Manual for Highway Bridge Maintenance inspection. For routine inspection, notes could be kept in masonry register a proforma as below.

Inspection of Roads, Bridges and Culverts.

a. Name, No. of the Highway. 

b. Culvert/bridge location Km. sub Km. 

c. Name of the Bridge/No.of culvert.

d. Name of the river/Nala/Creek. 

e. Type of Bridge: 

Pipes/Solid RCC.Slab/RCC.beam and deck slab/RCC.boxos/PSC.beams and slab/PSC/Box/Arch Concrete/masonry/structural steel/Truss/plate girder/R.S.J.S.

f. Openings:

i) Number.

i) Span/diameter.

iii) Maximum ht.of road level above bed 

iv) Vertical clearance above HFL. upto soffit Ht.of HFL. above road level, (for submersible bridge)

v) Design flood discharge cumecs, Design HFL 

vi) Type of foundation: Open/Faft/wolls/piles. 

vii) Total length m.

viii) Clear-road width between kerbs or wheel guards.

ix) Exposure: Severe/Moderate. 

x) ligh level/submersible.

xi) Design Live Load.

g.Year of construction.

h. Original cost

 

Date of Inspection	Name and Designation of Inspecting Officer	Result of Inspection defect and proposed remedial measures	Date of completion of proposed repairs	Remarks and signature of inspecting officers

Comprehensive inspection reports for bridges (including flyvovers, viaducts etc.) minor, major and long should be recorded in the proforma in the I.R.C. S.P. for comprehensive and special inspection photographs should be considered as essential record.

F. Follow up Action. 

Minor points or shotcomings noticed during ins pections will have to be immediately attended to by the concerned Executive Engineer and Deputy Engineer incharge. However, in case of any important or major short comings/distress noticed either during routine inspection or during comprehensive inspection. The matter shall be reported immediately to the Executive Engineer, Superintending Engineer and Chief Engineer in respect of minor bridges, major bridges and long bridges respectively. The latter (viz. E.E., S.E. or C.E. as the case may be) should decide the further line of action in consultation with the Designs Circle, if he considers it necessary, and give detailed instructions at to whether "special inspection" is called for and at what level & describe in details the various follow-up steps that are required to be taken including any restrictions in the traffic using the bridge.

CHECK LIST FOR INSPECTION REPORT

1. General

Name of bridge/No.of the bridge, Name of river.

Name, No. of the Highway, Bridge location.

2. Type of Bridge.

High level/submersible/high level submersible. 

3. Important Dates

    A. Date of last such inspection... by ...

    B. Date of last routine inspection.....

    C. Traffic intensity PCU/T per day ... (The latest census).

4. Approaches. 

4.1 Condition of pavement surface (report uneven- ness, settlement, cracking, pot holes etc.). 

4.2 Side slopes (report pitched or unpitched, con- dition of pitching/turfing any signs of slope failure etc.).

4.3 Erosion of embankment by rain cuts or any other damage to embankment. 

4.4 *Approach slab (report settlement, cracks, move- ment, etc.).

4.5 *Approach geometrics (report whether it satisfies the standards as in force).

4.6 *Accumulation of silt and debris on submersible approaches in cutting and embankment.

5. *Protective Works.

5.1 Type (mention whether guide bund of protection around abutments or spurs). 

5.2 *Report damage of the layout, cross section, pro- file (check whether the layout and the general cross sections are in order).

5.3 Report condition of slope pitching, apron and toe walls indicating the nature of damage if any (check for proper slope, thickness, pitching in the slopes, width and thickness of apron, erosion of toe walls, etc.).

5.4 Report condition of floor protection, works, indi ca te nature of damage if any (condition of impervious floor, flexible apron, curtain walls 

5.5 *Report any abnormal scour noticed. etc.).

5.6 Reserve stone material (check against specified quantity).

6. Waterway.

6.1 Report presence of obstruction, undergrowth etc, 

6.2 Report any abnormal change in flow pattern.

6.3 Report maximum flood level observed during the year and mark the same on the pier/abutment, both on the U/s and D/s.

6.4 Report abnormal afflux if any. 

6.5 Report adequacy of waterway.

7. Foundations. 

7.1 Report settlement shifting (of wells) if any.

7.2 Report cracking, disintegration, decay, erosion, cavitation etc. 

7.3 Report damage due to impact of floating bodies, boulders etc. 

7.4 For subways report seepage, if any, damage to the foundations etc. 

8. Substructures: (Piers, abutments, return walls and wing walls)

8.1 Report efficiency of drainage of the backfill behind abutments (check functioning of weep holes, evidence of moisture on abutment faces etc).

8.2 Report cracking, disintegration, decay etc.

8.3  For sub-ways report condition of side retaining walls like cracking, disintegration etc. and  seepage, if any.

8.4 Report large excavations done in the road below in case of flyover or Road over bridge or viaduct.

8.5 Report damages to protective measures to piers and abutments (for viaducts, flyovers and ROBS).

8.6  Report damages to protective coating or paint.

9. Bearings

9.1 Metallic bearings (State types sliding. plate rocker/roller).

9.1.1 Report general condition (check rusting, clean liness, ceasing of plates), silting accumulation of dirt in case of submersible bridges). 

9.1.2 Functioning (report excessive movement, tilting, Jumping off guides).

9.1.3 Greasing/oil bath (report date of last greasing/oil bath and whether to be redone or not).

9.1.4 Report effectiveness of anchor bolts (check whether they are in position and tight).

9.2 Elastomeric bearing (State No.). 

9.2.1 Report condition of pads (oxidation, creep, flattening, bulging, splitting).

9.2.2 Report general cleanliness.

9.3 Concrete bearings:

9.3.1 Report any signs of distress (cracking disintegration staining etc.).

9.3.2 Report any excessive tilting. 

9.3.3 Report loss of shape.

9.3.4 Report general cleanliness. 

9.4 Report cracks, if any, in supporting member (abutment cap, pier cap, pedestal).

10. Superstructure.

10.1 Reinforced concrete and prestressed concrete members.

10.1.1 Report spalling, disintegration or honeycombing, etc (special attention to be given to points of bearings).

10.1.2 Report cracking (pattern, location, explain preferably by plotting on sketch. A map of the cracking should be produced. The size and distribution of cracks and their penetration should be noted).

10.1.3 Raport available cover thickness to the rein- forcement (exposed reinforcement to be noted). 

101.4 Report water of deck surface.

10.1.5 Report scaling (this is gradual and continue loss of surface mortar and aggregate over irregular areas). 

10.1.6. Report surface stains and rust stains with locations.

10.1.7 Report leaching (effects are most usually evident on the soffits of decks).

10.1.8 Report corrosion of reinforcement, if any. 

10.1.9 Report leakage (leakage of water can take place through concrete decks, construction joints or thin component sections of the deck e.g. at kerbs etc.).

10.1.10 Report damages, if any, due to moving vehicles. 

10.1.11 Report condition of articulation (cracks if any)

10.1.12 Report perceptible vibrations, if any. 

10.1.13 Report excessive deflections (sag) or loss of camber, if any (measure at same point each time). 

10.1.14 Report cracks, if any, in end anchorage zone for prestressed concrete members. 

10.1.15 Report excessive deflection (sag) at central hinge, tip of cantilever for cantilever bridges. 

10.1.16 Prestressed concrete bridges should be given special attention and the possibility of the following additional defects should be noted:- 

a. Longitudinal cracks in the flanges. 

b. Spalling or cracking of concrete near curved cable ducts.

c. Shear cracks in webs nearer to supports. 

10.1.17 In box girders, the interior faces of flanges and webs need to be examined for signs of cracking and also to ensure that no excessive accumulation of water or debris is taking place for submersible bridges. Interior diaphragms will also require examination, particularly for any signs of cracking at their junction to the webs. 

10.1.18 Report accumulation of silt and debris on surface of deck (for submersible bridges). 

10.1.19 Report peeling off of protective coat or paint.

10.2  Steel Members.

10.2.1 Report condition of protective system. 

10.2.2 Report corrosion, if any.

10.2.3 Report excessive vibrations, if any. 

10.2.4 Report on alignment of members. 

10.2.5 Report condition of connecting (adequacy, loosenees of rivets, bolts or worn out welds, report specially on connection of stringers to cross girders, cross girders to main girders, gussets or splices, condition of hinges, splices etc.).

10.2.6 Report excessive loss of camber and excessive deflections and deformations, if any.

10.2.7 Report buckling, kinking, warping and waviness. 

10.2.8 Report on the cleanliness of members and joints (check choking of drainage holes provided in the bottom booms).

10.2.9 Report fracture apparent, if any. 

10.2.10 Report excessive wear (such as in pins in joints of truss) and their locations requiring close monitoring. 

10.2.11 Report conditions inside the closed member.

10.3 Masonry arches.

10.3.1 Report condition of joints mortar, pointing, masonry etc. 

10.3.2 Profile report (flattening by observing rise of the arch at centre and quarter points).

10.3.3 Report cracks if any (indicate location, pattern, extent, depth, explain by sketches). 

10.3.4 Check drainage of spandrel fillings (report bulging of spandrel walls if any).

10.3.5 Check growth of vegetation.

10.4 Cast Iron and Wrought Iron. 

10.4.1 These materials occur in older bridges and the defects which they exhibit are in general very similar to those described above for steel. It should be recognised that the homogeneity and purity of the material will not be upto the standards of present day steels, so that the inspection process has to take into account a range of material variability. Blow holes and cracking are probably the main defects that occur, the casting of the metal and cooling.

11. Expansion Joints

11.1 Functioning (report cracks in deck in the existing gap and approximate temperatures). 

11.2 Report condition of sealing material (for neoprene sealing material, check for splitting, oxidation, creep, flattening, bulging and for bitumen filler check for hardening, cracking etc.). 

11.3 Report secureness of the joints. 

11.4 Top sliding plate (report corrosion, damage to welds etc.). 

11.5 Locking of joints (report locking of joints especially for finger type expansion Joints). 

11.6  Check for debris in open joints.

11.7 Report rattling, if any.

11.8 Report drainage improvements for expansion joint needed, if any.

12. Wearing Coat (Concrete/Bitumen). 

12.1 Report surface condition (cracks, spalling, disintegration, pot holes etc.). 

12.2 Report evidence of wear (tell-tale rings, check for thickness as against actual thickness, report date of last inspection). 

12.3 Compare actual thickness with design thickness.

13. Drainage Spouts and Vent Holes.

13.1 Check clogging, deterioration and damage (if any). 

13.2 Check the projection of the spout on the underside (see whether structural members are being effected).

13.3 Report adequacy, thereof.

13.4 For sub-ways report about adequacy of drainage and pumping arrangements etc. 

13.5 For submersible bridges, report on functioning

14. Handrails, Parapets etc. 

14.1 Report general condition (check expansion gaps, missing parts, if any, etc.). 

14.2 Report damage due to collision.

14.3 Check alignment (report any abruptness in profile).

15. Footpath

15.1 Report general condition (danego dne to mounting of vehicles). 

15.2 Report missing footpath slabs.

16. Utilities 

16.1 Report leakage of water and sewage pipes.

16.2 Report any damage by telephone and electric cables.

16.3 Raport condition of lighting facilities. 

16.4 Report damages due to any other utilities.

17. Bridge Number 

17.1 Report condition of painting.

18. Aesthetics

18.1 Report any visual intrusion (bill boards, paints on structural members etc.).

19. Report whether all actions for maintenance and repairs recommended during last inspection have been done or not (give details).

20. Maintenance & Improvement Recommendations.

SR No	Item needing attention	Action recommended	Time when to be completed	Remarks and signature of inspecting officers
1	2	3	4	5

 Attach separate sheets for this as may be needed.