Steel Truss Components
Assembling & Erection Methodology
Safety before Launching
Safety After Launching
Description of Activities
Hazard Identification and Risk Assessment
HIRA of steel truss
• 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
• 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
• 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
•Hydraulic Jacks, Shifting and Fixing.
•Reinforcement Lifting, Shifting & fixing of pre-cast slab.
•Concreting by boom placer
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
Dimension of Assembled Steel Truss
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
Assembled steel truss before
launching on P157/159
walkie takie and
baton light from
pier cap 157
Steel truss launching fromT2 to
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
•Activation of supports to be checked during launching analysis.
•Launching pressure should not be exceeded 57 kg/m2
•Alignment & level of truss checked during launching.
•Free movement of truss verified.
•Safe access provided with hand rail protection along with safety net for
•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
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
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
VALUE Result of Hazard to Personnel
3 Reportable Injury or illness resulting in more than 2 days of work / Permanent Total
2 Non-Reportable Lost Time Injury or Illness resulting in less than 2 days off work
1 Injury or illness requiring First Aid treatment.
Torqueing & tightening of HSFG nut and bolt
Fall from height leads to personal injury
People at risk
Existing Control Measure
Rigid, Standard guard rails, mid rails , toe guard and fully
boarded 900mm working platform to be provided.
Use of PPE s, Work at height permit
Probability- 3 Severity- 4 Risk Rating-12(H)
Additional control Measure
Trained 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
Hazard Risk Involved Probability(P) SEVERITY(S
Total Risk Existing Control measure Control measure to be taken Probability Sever
1 Erection of scaffold &
of ground surface
3 4 12(H) Scaffold erected on compacted ground
Ensure base plate provided
Lifting permit to be taken
Ground surface to be checked
as per drawing
Prestart briefing to be given
1 4 4(M)
2 Lifting of steel truss
accessories/ assembly by
Crane toppling Improper
crane leads to
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
to the parts to be
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
1 3 3(L)
4 Launching of steel truss Improper balancing
on Hillman roller
3 3 9(H) Below area is barricaded.
Hillman roller area to be checked before
Rollers to be lubricated before
No loose material should be
kept on top.
Pre start briefing
2 1 2(L)
5 Hydraulic jack shifting,
fixing & operation, span
Leakage of hydraulic
Slip hazard 3 4 12(H) Preventive Maintenance
Use of PPEs by worker
O rings to be checked on
Workers not to stand below
1 2 2(L)
6 Traffic Management Hit by moving Personal 3 4 12(H) Work execute as per traffic management Clear identification of signage 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
• 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.