Submitted by Sourav Kumar

PradhanRoll No.-214CH2529

IntroductionSteel Truss ComponentsLaunching AccessoriesAssembling & Erection MethodologyLaunching ProcedureLaunching PhotosSafety before LaunchingSafety After LaunchingDescription of ActivitiesHazard Identification and Risk Assessment Risk HierarchyRisk ControlsHIRA of steel trussConclusion

• A truss bridge is a bridge whose load bearing superstructure is composed of a truss, a structure of connected elements forming triangular units.• This steel truss is a bridge which connects the viaduct at various locations on special spans where the launching is not possible with the Launching girder and cannot erect any other parts of viaduct spans i.e. I Girder and box girder.• After Railway Board banning use of concrete girders beyond 24.4m spans the railways decided to shift welded girder as good alternative of concrete girder.

• The objective is to describe and furnish details of safety in construction of obligatory steel span of (MRTS) crossing of Delhi Metro CC -28.This dissertation work mainly focus on steel truss construction and its safe work procedure, risk assessment and eliminating hazards.The important objective is to keep workmen and engineer out of danger by assessing risk of every activity before and during launching of steel truss.

• Bottom Chord• Bottom Lateral Bracing• Top Chord• Top Lateral Bracing• Vertical Chord• Diagonal Chord• Portal Strut• End Racker• Stringer

• Intermediate trestle for launching• Spreader beam• Pulling frame• Lateral guide beam arrangement• Hold down arrangement• Hillman roller with supporting stool• Strand Jack• Camber Jack

  

 

 

• Temporary trestles are provided for supporting of steel truss during assembling and launching.

• It is located at beneath of bottom chord.• Hillman roller of a suitable capacity is fixed on the top of the trestle.• Assembling is done on the heavy duty towers.• First bottom chord members are erected.• Vertical and diagonal members chords are erected.• Splicing is done with the vertical members.• Top horizontal bracing , plan bracing & temporary bracing are erected.

• Area Levelling•Erection of Scaffold/Trestles•Transportation of steel truss•Lifting of Steel truss accessories/Assembly by crane•Load transferring on the trestle from scaffold•Fixing of strands with anchor plates up to spreader beams•Transferring load on Hillman rollers and activation of Hold down arrangement•Lowering of DOCA from steel truss arrangement•Launching work/Operation of pulling frame/Activation of hold down arrangement•Hydraulic Jacks, Shifting and Fixing.•Jack Operation•Traffic Management•Reinforcement Lifting, Shifting & fixing of pre-cast slab.•Concreting by boom placer•De-shuttering

Pier 156-157,Rajouri Garden,Delhi•Type of Truss- Steel Truss•Dimension of truss-60 m x 12.5 m x 8.805 m (Tentative) •Over al depth of the truss-8.8m • Assumed Weight Of Truss- 371 MT •Width of the truss- 12.15m •Thickness of the deck slab- 200m •Length of the truss- 30m

•Span Arrangement-60 m

Span Location

Dimension of Assembled Steel Truss

View of Erected Truss over Pier

1. Temporary supporting trestle – 08 Nos. as required (For supporting Truss)

2. Hillman rollers with 200T capacity – 22 Nos. as required (For enabling Truss launching)

3. Formwork staging - (For enabling truss and access)

4. Crane with suitable capacity – 01 Nos. (For assembling of Truss)

5. Multi Strand monopull Jack with 1m stroke 50mt capacity– 03 Nos.

6. Pulling strands HTS – 170RM

7. For lowering 200MT double acting jack with locknut arrangement with 200mm stroke – 06 No

Assembled steel truss before launching on P157/159

Signaler with walkie takie and baton light from

pier cap 157

Steel truss launching fromT2 to T1

Steel truss launching from pier 157

After final launching steel truss on P156Launching of steel truss finished

from P 159 to 157

Wedge locking of Hillman roller

Wood Packing

•Activation of supports to be checked during launching analysis.•Launching pressure should not be exceeded 57 kg/m2 during launching.•Alignment & level of truss checked during launching.•Free movement of truss verified.•Safe access provided with hand rail protection along with safety net for trestle.•Availability of steel wedges in supports to be checked.•Vertically checking in intermediate trestles should be checked.•Velocity of wind not exceeding 23 m/s should be verified.•Bottom chord splice plate obstructing Hillman roller should be checked.

• Locking of Hillman rollers by steel wedges to be checked.• Steel packing should be provided for OWG at reached pier and trestle.• Holding down arrangement should be activated.• Level of truss in each supports should be checked.• Velocity of speed not exceeding 24m/s should be verified.

Green indicates “ low risk”

Yellow indicates “moderate risk”

Red indicates “ high risk”

From 1 to 3, it is low risk.

From 4 to 8, it is moderate risk

From 9 to 16, it is very high level of risk

Probability Description

VALUE Status Description

4 Very Likely The event is almost certain to occur and has occurred repeatedly

3 Most Likely The event will probably occur in most circumstances

2 Unlikely The event may occur only in exceptional circumstances

1 Very Unlikely Very unlikely but remotely possible

Severity Descriptions

VALUE Result of Hazard to Personnel

4 Fatality

3 Reportable Injury or illness resulting in more than 2 days of work / Permanent Total Disability

2 Non-Reportable Lost Time Injury or Illness resulting in less than 2 days off work

1 Injury or illness requiring First Aid treatment.

ActivityTorqueing & tightening of HSFG nut and boltRiskFall from height leads to personal injuryPeople at riskWorkmen/ RiggerExisting Control MeasureRigid, Standard guard rails, mid rails , toe guard and fully boarded 900mm working platform to be provided.Use of PPE s, Work at height permitProbability- 3 Severity- 4 Risk Rating-12(H)Additional control MeasureTrained rigger to be deployed, Prestart briefing to be given before starting of work, Close supervision to be ensured.Probability- 1 Severity- 4 Risk Rating-4 (M)

• Working at Height• Vehicle plant & Equipment• Temporary Work Formwork• Crane Lifting• Working With Electricity• Working in OH & UG area• Working adjacent in public area• Environmental Aspects• Personal Protective Equipment

SL.

NO.

Activity/

Observation

Hazard Risk Involved Probability(P) SEVERITY(S

)

Total Risk Existing Control measure Control measure to be taken Probability Sever

ity

Residual Risk

1 Erection of scaffold & trestle

Uneven condition of ground surface

Collapse of scaffold &

trestle

3 4 12(H) Scaffold erected on compacted ground floor

Ensure base plate provided

Lifting permit to be takenGround surface to be checked

as per drawingPrestart briefing to be given

1 4 4(M)

2 Lifting of steel truss accessories/ assembly by

crane

Crane toppling

Improper positioning of

crane leads to collapse and property

damage

3 4 12(H) Crane positioned on firm ground surface

Authorized riggers to be engaged

Green card system followed

Daily crane inspection checklist to be followed.

Lift plan to be ensured

1 4 4(M)

3 Welding operation of

temporary work

Improper earthing

to the parts to be welded

Electrocution,

burning of welding cables and fire hazard

3

2

6(L)

Return earth given through the welding

Hot work permit to be taken

Daily operator Checklist to be provided

No rebar to used for return

lead

1

3

3(L)

4 Launching of steel truss Improper balancing on Hillman roller

Tilting of Hillman roller

causing damage of rollers

3 3 9(H) Below area is barricaded.Hillman roller area to be checked before

erection periodically

Rollers to be lubricated before use.

No loose material should be kept on top.Pre start briefing

2 1 2(L)

5 Hydraulic jack shifting, fixing & operation, span lowering

Leakage of hydraulic fuel

Slip hazard 3 4 12(H) Preventive Maintenance

Use of PPEs by worker

O rings to be checked on periodical basis

Workers not to stand below

that area

1 2 2(L)

6 Traffic Management Hit by moving

vehicle

Personal

injury / fatality/ property damage

3 4 12(H) Work execute as per traffic management

planBarricading fixed with retro reflective blinker lighting , red tape, water barrier

Traffic Marshals with Red and green flag

Clear identification of signage

to be place in foot path, bus stop, lamp post, new traffic signal

1 4 4(L)

• Steel truss erection, assembling and launching process includes much more safety precaution. Risk assessment is necessary for determining the level of risk in each activity to detect hazard and taking control measures to avoid any incident.

• Additional control measures and existing control measure can be modified by following learning by doing procedure.

• Awareness regarding safety has been created among staffs, employees and engineers by showing the risk level and their consequences.

• Safe working procedure for completing work in safest manner are described in safe work method.• Risk assessment review and update on specific interval is necessary to know the present scenarios. • STOP WORK notice is much more needed when unsafe practices / conditions observed.