UNIVERSITY OF SOUTH AFRICA
College of Science, Engineering and Technology
⋄ ⋄ ⋄ ⋄ ⋄ ⋄ ⋄ ⋄ ⋄⋄
CMT2601: Construction
Methods in Civil Engineering
Assignment 2 — Year Module, 2026
⋄ ⋄ ⋄ ⋄ ⋄ ⋄ ⋄ ⋄ ⋄⋄
CMT2601
Module Code:
Construction Methods
Module Name:
Assignment 2
Assignment:
2026
Due Date:
48
Total Marks:
Submitted in partial fulfilment of the requirements for CMT2601 — UNISA 2026
,UNISA | CMT2601 Construction Methods – Assignment 2
Question 1: Risk Assessment in Large Infrastructure Projects
Question 1.1 – Explain why a risk assessment must be conducted before starting con-
struction activities on large infrastructure projects such as harbours, railways, or air-
ports. [5 marks]
Question:
Explain why a risk assessment must be conducted before starting construction activities on
large infrastructure projects such as harbours, railways, or airports.
Answer:
Before any major construction begins, a risk assessment gives the project team a clear picture
of what could go wrong and what it would cost if it did. On projects of this scale, the conse-
quences of getting that wrong are not minor. A harbour wall that fails, a railway embankment
that slips, or a runway that cracks under aircraft loading can set a project back by years and
injure or kill people in the process (Hinze, 2011).
The first purpose of a risk assessment is to identify hazards specific to the site and the type of
work. Large infrastructure projects involve activities that do not occur on ordinary building
sites, such as marine piling, blasting, earthworks on soft ground, and construction adjacent
to live transport corridors. Each of these presents risks that are not obvious until they are
formally mapped out (Department of Labour, 2003).
Once hazards are identified, the assessment ranks them by likelihood and severity. This rank-
ing tells the project team where to direct protective measures first. It would be impractical
to treat every possible risk with the same level of response; prioritisation is what makes risk
management workable in practice (Zou, Zhang and Wang, 2007).
Risk assessment also serves a legal function. In South Africa, the Construction Regulations
(2014) under the Occupational Health and Safety Act 85 of 1993 require a baseline risk as-
sessment before construction begins. Non-compliance exposes the contractor, the client, and
the professional team to criminal liability. On infrastructure projects involving public money,
regulatory compliance is not optional.
Beyond safety, financial exposure is significant. Cost overruns and delays on harbour, rail,
and airport projects are historically large. A risk register developed before construction be-
gins allows contingency budgets to be allocated accurately, and gives the project manager a
Page 2 of 16
,UNISA | CMT2601 Construction Methods – Assignment 2
documented basis for claims or variation orders if a risk event materialises (Zou et al., 2007).
Finally, a risk assessment protects the environment. Coastal harbours, railway cuttings through
wetlands, and airport runways near aquifers all carry environmental risks that must be as-
sessed and mitigated before ground is broken. Environmental damage discovered mid-construction
can shut a project down entirely.
Critical Consideration
In South Africa, the Construction Regulations (2014) require the contractor to submit
a health and safety plan based on a risk assessment before the employer may allow
construction to proceed. Failure to do so constitutes a criminal offence under section
38(1)(a) of the OHS Act.
Page 3 of 16
,UNISA | CMT2601 Construction Methods – Assignment 2
Question 2: Quay Wall Construction Scenario
Question 2.1 – Explain how strong wave action can affect the structural stability of
a quay wall under construction. [5 marks]
Question:
Explain how strong wave action can affect the structural stability of a quay wall under con-
struction.
Answer:
A quay wall under construction is at its most vulnerable before the structure reaches its de-
signed strength and before backfill and toe protection are in place. Strong wave action during
this period can cause several forms of structural distress.
Wave impact generates dynamic lateral forces on the face of the wall. During construction, the
wall may not yet be fully connected to its foundation or have its full structural weight in place.
Therefore, the lateral force from a breaking wave can exceed the wall’s resistance, causing
forward displacement or rotation at the base (CIRIA, 2007).
Wave run-up and overtopping erode the backfill material placed behind the wall. If backfill
is loosely compacted or has not yet consolidated, repeated water infiltration and drawdown
wash fines from the fill, creating voids. These voids reduce the passive resistance that the fill
provides to the wall, making it more susceptible to sliding (PIANC, 2010).
Wave action also generates cyclic pore water pressure in saturated foundation soils. This re-
peated loading and unloading can lead to liquefaction in loose sandy seabed soils, effectively
removing the bearing capacity beneath the wall’s toe. Settlement or tilting follows (CIRIA,
2007).
During construction, the toe of the wall, which in the finished structure carries the rock ar-
mour or concrete units that absorb wave energy, is often not yet installed. Without this pro-
tection, wave scour removes bed material directly from beneath the foundation, undermining
the wall.
Finally, floating plant such as barges, cranes, and jack-up vessels moored alongside the wall
are pushed into contact with it by waves. The repeated impact of heavy marine equipment
against an incomplete structure can crack precast concrete panels and shear connection bolts.
Page 4 of 16
, UNISA | CMT2601 Construction Methods – Assignment 2
Quality Assurance
Construction scheduling should avoid marine piling and panel installation during sea-
sons with predicted significant wave heights above the structural design tolerance. On
the South African east coast, the summer months bring swells generated by tropical
systems that can reach 4–6 metres with little warning.
Question 2.2 – Discuss how sediment buildup at the harbour entrance can affect har-
bour operations and vessel movement. [4 marks]
Question:
Discuss how sediment buildup at the harbour entrance can affect harbour operations and
vessel movement.
Answer:
Sedimentation at a harbour entrance is a persistent operational problem, particularly where
the harbour is located on a coast with high longshore sediment transport, such as much of the
KwaZulu-Natal and Eastern Cape coastline.
The primary effect is a reduction in channel depth. Most commercial and fishing vessels op-
erate at specific draught requirements. When sediment accumulates in the entrance channel,
the available underkeel clearance decreases. Vessels that previously entered without restriction
must either reduce their cargo load, wait for a high tide, or divert to another port (PIANC,
2010). For container terminals and bulk carriers operating on tight schedules, this directly
increases the cost of port calls.
Sedimentation changes the cross-section of the entrance channel, which alters tidal flow ve-
locities. In some cases, faster currents develop through the narrowed passage, making vessel
navigation more difficult, especially for smaller craft. In other cases, the shoal diverts flow and
creates eddies that make it hard to maintain a straight track through the entrance.
If sediment builds above the design depth, vessels face grounding risk. A grounding in the
harbour entrance can block the channel entirely, stopping all traffic in and out until salvage is
complete, which can take days or weeks (CIRIA, 2007).
Regular dredging is the standard response, but dredging has its own costs. Disposal of dredged
material requires environmental approval, and the process disrupts port operations during exe-
Page 5 of 16
College of Science, Engineering and Technology
⋄ ⋄ ⋄ ⋄ ⋄ ⋄ ⋄ ⋄ ⋄⋄
CMT2601: Construction
Methods in Civil Engineering
Assignment 2 — Year Module, 2026
⋄ ⋄ ⋄ ⋄ ⋄ ⋄ ⋄ ⋄ ⋄⋄
CMT2601
Module Code:
Construction Methods
Module Name:
Assignment 2
Assignment:
2026
Due Date:
48
Total Marks:
Submitted in partial fulfilment of the requirements for CMT2601 — UNISA 2026
,UNISA | CMT2601 Construction Methods – Assignment 2
Question 1: Risk Assessment in Large Infrastructure Projects
Question 1.1 – Explain why a risk assessment must be conducted before starting con-
struction activities on large infrastructure projects such as harbours, railways, or air-
ports. [5 marks]
Question:
Explain why a risk assessment must be conducted before starting construction activities on
large infrastructure projects such as harbours, railways, or airports.
Answer:
Before any major construction begins, a risk assessment gives the project team a clear picture
of what could go wrong and what it would cost if it did. On projects of this scale, the conse-
quences of getting that wrong are not minor. A harbour wall that fails, a railway embankment
that slips, or a runway that cracks under aircraft loading can set a project back by years and
injure or kill people in the process (Hinze, 2011).
The first purpose of a risk assessment is to identify hazards specific to the site and the type of
work. Large infrastructure projects involve activities that do not occur on ordinary building
sites, such as marine piling, blasting, earthworks on soft ground, and construction adjacent
to live transport corridors. Each of these presents risks that are not obvious until they are
formally mapped out (Department of Labour, 2003).
Once hazards are identified, the assessment ranks them by likelihood and severity. This rank-
ing tells the project team where to direct protective measures first. It would be impractical
to treat every possible risk with the same level of response; prioritisation is what makes risk
management workable in practice (Zou, Zhang and Wang, 2007).
Risk assessment also serves a legal function. In South Africa, the Construction Regulations
(2014) under the Occupational Health and Safety Act 85 of 1993 require a baseline risk as-
sessment before construction begins. Non-compliance exposes the contractor, the client, and
the professional team to criminal liability. On infrastructure projects involving public money,
regulatory compliance is not optional.
Beyond safety, financial exposure is significant. Cost overruns and delays on harbour, rail,
and airport projects are historically large. A risk register developed before construction be-
gins allows contingency budgets to be allocated accurately, and gives the project manager a
Page 2 of 16
,UNISA | CMT2601 Construction Methods – Assignment 2
documented basis for claims or variation orders if a risk event materialises (Zou et al., 2007).
Finally, a risk assessment protects the environment. Coastal harbours, railway cuttings through
wetlands, and airport runways near aquifers all carry environmental risks that must be as-
sessed and mitigated before ground is broken. Environmental damage discovered mid-construction
can shut a project down entirely.
Critical Consideration
In South Africa, the Construction Regulations (2014) require the contractor to submit
a health and safety plan based on a risk assessment before the employer may allow
construction to proceed. Failure to do so constitutes a criminal offence under section
38(1)(a) of the OHS Act.
Page 3 of 16
,UNISA | CMT2601 Construction Methods – Assignment 2
Question 2: Quay Wall Construction Scenario
Question 2.1 – Explain how strong wave action can affect the structural stability of
a quay wall under construction. [5 marks]
Question:
Explain how strong wave action can affect the structural stability of a quay wall under con-
struction.
Answer:
A quay wall under construction is at its most vulnerable before the structure reaches its de-
signed strength and before backfill and toe protection are in place. Strong wave action during
this period can cause several forms of structural distress.
Wave impact generates dynamic lateral forces on the face of the wall. During construction, the
wall may not yet be fully connected to its foundation or have its full structural weight in place.
Therefore, the lateral force from a breaking wave can exceed the wall’s resistance, causing
forward displacement or rotation at the base (CIRIA, 2007).
Wave run-up and overtopping erode the backfill material placed behind the wall. If backfill
is loosely compacted or has not yet consolidated, repeated water infiltration and drawdown
wash fines from the fill, creating voids. These voids reduce the passive resistance that the fill
provides to the wall, making it more susceptible to sliding (PIANC, 2010).
Wave action also generates cyclic pore water pressure in saturated foundation soils. This re-
peated loading and unloading can lead to liquefaction in loose sandy seabed soils, effectively
removing the bearing capacity beneath the wall’s toe. Settlement or tilting follows (CIRIA,
2007).
During construction, the toe of the wall, which in the finished structure carries the rock ar-
mour or concrete units that absorb wave energy, is often not yet installed. Without this pro-
tection, wave scour removes bed material directly from beneath the foundation, undermining
the wall.
Finally, floating plant such as barges, cranes, and jack-up vessels moored alongside the wall
are pushed into contact with it by waves. The repeated impact of heavy marine equipment
against an incomplete structure can crack precast concrete panels and shear connection bolts.
Page 4 of 16
, UNISA | CMT2601 Construction Methods – Assignment 2
Quality Assurance
Construction scheduling should avoid marine piling and panel installation during sea-
sons with predicted significant wave heights above the structural design tolerance. On
the South African east coast, the summer months bring swells generated by tropical
systems that can reach 4–6 metres with little warning.
Question 2.2 – Discuss how sediment buildup at the harbour entrance can affect har-
bour operations and vessel movement. [4 marks]
Question:
Discuss how sediment buildup at the harbour entrance can affect harbour operations and
vessel movement.
Answer:
Sedimentation at a harbour entrance is a persistent operational problem, particularly where
the harbour is located on a coast with high longshore sediment transport, such as much of the
KwaZulu-Natal and Eastern Cape coastline.
The primary effect is a reduction in channel depth. Most commercial and fishing vessels op-
erate at specific draught requirements. When sediment accumulates in the entrance channel,
the available underkeel clearance decreases. Vessels that previously entered without restriction
must either reduce their cargo load, wait for a high tide, or divert to another port (PIANC,
2010). For container terminals and bulk carriers operating on tight schedules, this directly
increases the cost of port calls.
Sedimentation changes the cross-section of the entrance channel, which alters tidal flow ve-
locities. In some cases, faster currents develop through the narrowed passage, making vessel
navigation more difficult, especially for smaller craft. In other cases, the shoal diverts flow and
creates eddies that make it hard to maintain a straight track through the entrance.
If sediment builds above the design depth, vessels face grounding risk. A grounding in the
harbour entrance can block the channel entirely, stopping all traffic in and out until salvage is
complete, which can take days or weeks (CIRIA, 2007).
Regular dredging is the standard response, but dredging has its own costs. Disposal of dredged
material requires environmental approval, and the process disrupts port operations during exe-
Page 5 of 16
