1. Before proceed with any works, survey and setting out shall be conducted to
provide the guide on levels and alignment for the construction of the Reinforce
concrete Retaining Walls.
2. Survey and setting out shall be done in the present of Resident Engineer or his
3. Request for inspection shall be submitted prior to start the works.
Stage 2.: Earthworks (Excavation)
1. Earthworks can only commence after the setting out was done and accepted by
2. The sequence of the Earthworks is as the following Diagram 1.
3. The excavation at Sequence 1 will be done until it reaches the proposed platform level
where it will provide wider temporary diversion during the construction of the Retaining
4. The excavation work at sequence 2 will only commence after the completion of sequence 1.
5. The sequence 2 will provide access for existing traffic during the excavation work
activities at sequence 1.
6. The Layout after completion of earthworks activities for both sequences will be as the
following Diagram 2.
Stage 3: Construction of RC Retaining Wall Structure.
Level 1: Piling Works
1. Piling works will commence after the completion of first half of the sequence 2
2. The sequence of the piling works will be done starting form the end Chainage
of the Retaining wall progressing to the front Chainage.
3. The excess of drive R.C pile will be cut as soon as the Piling works reaches
practical numbers of piling points to enable the pile cut off activities.
Level 2 : construction of the R.C Retaining wall Base.
1. The construction of the base will commence as soon as after the preparation of the
pile head reaches the practical length of the standard steel bar supply length or
available safe working area. (eg. Standard steel bar supply length / pcs = 12m )
2. All of the installed reinforcement must be free from rust, properly tied and being
installed according to construction drawings and specifications.
Level 3: Concreting works.
1. Concreting works will only commence after the installed reinforcement being
inspected and accepted and approved for next sequence of works by Resident Engineer
or his or her representative.
2. The sequence of concreting activities will also start from the end chainage of the R.C
Retaining Wall base.
3. Concreting works will commence as soon as the installed reinforcement for the base
reaches the possible delivery concrete volume to site per day and practical output of
the concreting works.
4. Prior to concreting activities, all installed formworks for the base shall be properly secure
to avoid formwork failure.
5. During concreting activities, test cube and numbers of the cube to be prepared shall be
as per directed by Resident engineer or his or her representative.
6. There shall be no concreting activities during raining day.
7. The flow of the installation of the reinforcements and concreting activities shall be as
per diagram 3.
Level 4: Construction or R.C Wall.
1. The construction of the R.C concrete wall shall proceed as soon as the Concreted base
is ready to accept the next sequence of the works.
2. Construction of the wall shall start for both side of the retaining wall concurrently.
However some section of the wall might need to be left open to suite the site condition and
the movement of machineries.
3. R.C wall construction activities shall start from end chainage of the retaining wall.
4. The height of each wall that is ready for concreting shall not exceed 2.4 meter high. This is
to avoid the formwork failure.
5. Prior to fully erect the formwork, wall reinforcement must be inspecting by Resident engineer
or his representative for acceptance and approval for next sequence of work.
6. Prior to concreting activities formwork shall be properly secured to avoid formwork failure
during concreting activities.
7. There shall be no concreting activities conducted during raining day.
8. Flow of the R.C Wall Construction is as shown in the following Diagram 4.
Stage 4: Backfilling to completed Retaining Wall.
1. Backfilling activities will commence as soon as the fully completed section of the
retaining wall is ready to received backfill material and also practically safe for the
other on-going construction activities for remaining Retaining wall structure.
2. Each layer of backfill shall be not more than 500mm thick and shall be properly
compacted before laying of subsequence layer of backfill. This process is repeated
until the whole height of the retaining wall if filled.
3. Backfill activities will commence from the end chainage of the retaining wall towards
the CH 6 + 200.
Stage 5: Miscellaneous works.
1. Miscellaneous works will commence upon completion of the whole retaining wall
structure inclusive of backfilling works.
2. The miscellaneous works are the flexible pavement, drains and road furniture.
Overall sequence of the stages: