Civil engineering involves the research, design, construction, and maintenance of the physical and natural built environment. It covers:

structures (including those made from steel, concrete or timber), for example, roads, railways, bridges, airports, pipelines, dams, canals, harbours, dockyards, towers, and buildings.

analysing the likely behaviour of soil and rock when placed under pressure by proposed structures and designing above and below ground foundations.

environmental impacts, for example, transport, urban development and municipal services, resource protection of building and construction of other infrastructure and service industries, and

collecting sewage and industrial wastes.

Civil engineering has many different areas of focus or speciality areas. As a guide, some of the main areas of focus are:

structural engineering

geotechnical engineering, and

hydrology engineering.

A civil engineer who intends to work in the building industry must:
be registered as a professional engineer in the area of civil engineering, and

have their registration endorsed to work in the building industry in the area of civil engineering.

Civil engineers working in the building industry can work with foundations and footings systems, construction materials and structural systems, and hydraulic supply and waste systems.

Mechanical engineering is concerned with the research, design, construction, analysis, manufacture and maintenance of devices, machines and mechanical structures and systems that may include mechanical equipment, cranes, weigh bridges, lifts, conveyors, air conditioning plants, production plants, ventilation systems, lathes, hoppers, pipelines, wind turbines and manufacturing systems.
It also involves the production and usage of heat and mechanical power for the design, production, and operation of systems, machines, and tools.
Mechanical engineering has many different areas of focus. As a guide, some of the main areas of focus are:

acoustic engineering

aerospace and aeronautical engineering

equipment engineering (including automotive and manufacturing)

piping engineering, and

structural analysis engineering.

Professional engineers providing professional engineering services in any of the above or other areas of focus must be registered in the area of mechanical engineering.
A mechanical engineer who intends to work in the building industry must:

be registered as a professional engineer in the area of mechanical engineering, and

have their registration endorsed to work in the building industry in the area of mechanical engineering.

Mechanical engineers working in the building industry can work with mechanical systems for vertical transport, heating ventilation, air conditioning and refrigeration (HVAC-R) and smoke control, thermal and environmental systems, and systems to aid the disabled.

Structural engineering is an area of focus of civil engineering.
It primarily deals with the research, design, construction, monitoring, maintenance, rehabilitation, and demolition of permanent and temporary structures. Structures include, for example, buildings, bridges, in-ground structures, footings, large tanks, silos, mining structures and various plants, and frameworks and space frames.
A structural engineer who intends to work in the building industry must:

be registered as a professional engineer in the area of structural engineering, and

have their registration endorsed to work in the building industry in the area of structural engineering.

As with civil engineers, structural engineers working in the building industry can work with foundations and footings systems, construction materials and structural systems.

Electrical engineering is concerned with the design, application, manufacture and maintenance of equipment, devices, plant, and systems which use electricity, electronics, and electromagnetism.
These activities can apply to electricity generation, transmission, distribution, electrical installations in buildings and on industrial sites, electrical equipment manufacture, instrumentation and control system applications in industry, communications networks, electronic plan, and equipment, and the integration and control of computer systems.
Electrical engineering has many different areas of focus. As a guide, some of the main areas of focus are:

power engineering

control engineering

electronics engineering, and

telecommunications engineering (such as signal processing, signalling and communications and radiofrequency engineering).

Professional engineers providing professional engineering services in any of the above or other areas of focus must be registered in the area of electrical engineering.
An electrical engineer who intends to work in the building industry must:

be registered as a professional engineer in the area of electrical engineering, and

have their registration endorsed to work in the building industry in the area of electrical engineering.

Electrical engineers working in the building industry can work with electronic data transmission, security and communications systems, lighting systems and control systems for vertical transport, HVAC-R and fire detection.