Question

1) What are the Special requirements, such as snow and ice control, dust control, landslides, ground improvement when doing a NEW road project connecting any two locations situated in Australia. Please explain much as possible

Answer 1

Australia is the world's biggest island and the smallest continent. To join any two places in a country of such huge extend is a real challenge both in terms of physical and  economics barriers. Australia is considered to be a country of very low  population density, hence there are many remote areas where performing an infrastructure activity is really challenging and costly. The challenge is mainly in terms of physical barriers and climatic conditions. Australia has got almost 17 % of its total area as deserts and close to 16 % as natural or native forest cover.

The greatest challenges that can be expected in the infrastructure works are:

1. Snow and ice cover - The Alpine region of Australia experiences significant snowfall. Therefore the roads to be constructed in this regions must maintain sufficient cross slope do that the snow can be easily wiped off to the sides. The construction activity to take place in non-winter months otherwise it as almost impossible to lay roads or rails at the time of snowfall.

2. Land-slides - These are problems taking place in the roads constructed by cutting a slope in a hilly terrain. To avoid these, we need to analyse the slope stability of the area and determine a factor of safety close to 3. If the required Factor of safety is not available , we need to construct a wall or barrier on the side of the slope, like a retaining wall, to retain the earth, thus protecting from land-slides.

3. Tunnelling- At times digging a small tunnel through a hill or a mountain can save a lot o distance while going around the obstruction. The designing team must do a cost benefit analysis so as to construct a round about or a tunnel. If the tunnel works out to be economic then we need heavy construction equipments to cut the hard rock through the hill and simultaneously fix the sides of the tunnel with concrete. At the time of construction, as no roads are available , its very challenging to bring such heavy machine up a hill or mountain where tunnelling is to be done.

4 Maintaining proper longitudinal slopes - We need to maintain proper longitudinal slopes in mountainous roads so that for a particular design speed there is sufficient SSD (Stopping Sight Distance) available to avoid accidents and also maintain a proper compensated gradient (Since the full howling power of engines are not available to push a car up in a curve, hence we need to reduce the gradient of roads in curves known as compensated gradient).

5 Ground Improvement - In case of uneven grounds or rolling terrain, we need the use the " cut and fill " technique to overcome the challenge in these places. If we do not do so, the road will turn out to be very uneven causing discomfort to the passengers using the road.. Hence we need to cut the excess earth and fill it in place of depression.

6. Ground Stabilisation -  If the roads pass through marshy soil, where the soil is not stable enough to bear the loads, then we need to stabilise the soil using various techniques before the construction begins. The various techniques that can be used to stabilise the soil are - Lime stabilisation, Cement stabilisation and many other techniques. After that we can go for the sub-grade construction and henceforth the upper layers may be constructed.

7 Rain - water Control - In areas of heavy rainfall, firstly we need to stabilise the soil and another challenging aspect is the lowering of ground water table. We need to install tile drains, which will absorb the water from the nearby soil and will not allow the ground water to rise beyond a certain level which in tern will protect the pavement.

8. Dust Control - Its another very challenging aspect in the desert areas where dust can cause nuisance . Few important techniques for dust control are :

a ) At the time of construction , its important to protect the sensitive equipments or else dust can damage it

b) Timely application of water to settle the dust particles

c) Covering the unpaved surface of earth with gravel or some impermeable membrane

These are some of the important challenges that a infrastructure development authority might face while constructing roads in Australia. I have written these points keeping in mind the diverse physical and climatic variations of Australia.

Thank You.