Singapore roads go green

LTA to test if roads can be made up of more recycled material
Maria Almenoar, Straits Times 19 Mar 09;

MORE of what you dump will soon go into building new roads.

The Land Transport Authority (LTA) is aiming to increase the composition of recycled materials in Singapore's roads to 70 per cent, up from 25 per cent now.

Doing this will not only make Singapore greener, it will also save the authorities millions of dollars, reduce the country's reliance on imported materials, and reduce the speed at which landfills pile up.

To test the sustainability of green roads, a 200m stretch along Tampines Road towards the Kallang-Paya Lebar Expressway will be used.

Three 50m stretches will be paved with recycled materials of varying concentrations, while the remaining 50m stretch will be paved in the conventional way and act as a test section.

This site was chosen because it is close to a heavy vehicle carpark and the volume of traffic using the area is high, said the LTA.

The stretch will be monitored for six months before a decision is made on whether recycled material is suitable for use on all other roads.

Singapore roads are laid using four layers. Currently, granite is the predominant material used in all the layers.

The new method will use processed incinerated waste from landfills, mostly discarded household items, to fill the bottom two layers.

The material, called Incineration Bottom Ash, or IBA, contains mainly silica, ceramic, glass and metal.

IBA is made by exposing incinerated waste to the weather for three months to allow it to dry. After this, it is screened to remove unwanted materials, and then sieved into the required size before being treated with chemicals.

The top two layers, which will comprise recycled material - 30 per cent - and a mix of new aggregate materials imported from Indonesia or Malaysia and some granite, are then filled in.

The recycled material is called Reclaimed Asphalt Pavement, or what is dug up from the top layer of roads when they are resurfaced.

Countries such as Japan, the United States and Britain already use recycled materials in their road construction.

Yesterday, LTA's deputy chief executive of infrastructure and development, Mr Lim Bok Ngam, said Singapore is highly exposed to fluctuations in the price of granite, which costs about $30 a tonne now, but hit a high of $80 a tonne about two years ago. LTA uses three million tonnes of the material a year.

Switching to recycled and other materials, Mr Lim said, will remove much of the impact of such fluctuations.

'When you import granite, sometimes you are paying beyond cojavascript:void(0)st because it's driven up by political reasons or the market,' he added.

Pilot project to build Singapore's "green" road kicks off
Asha Popatlal, Channel NewsAsia 18 Mar 09;

SINGAPORE: A pilot project by the Land Transport Authority (LTA) to construct Singapore's "green" road using recycled materials has kicked off.

If successful, it could lead to savings of millions of dollars annually.

Using recycled materials to build roads in Singapore is not new.

It has been done for the last 20 years and about a quarter of the roads today have some form of recycled materials in them.

What makes the latest trial different is that a mix of recycled materials will now be used extensively in all four layers of the road structure, instead of just one layer as was done previously.

If the scheme works, the advantage is two-fold.

Firstly, Singapore can reduce its dependence on the import of expensive raw materials like granite from neighbouring countries.

Secondly, it is cheaper to build such roads as one of the recycled materials used is waste generated within the country.

Household rubbish which has been burnt and processed is one material which will be used to construct the third and fourth layers of the road in the green pavement trial.

Today, an average of 2,000 tonnes of waste is dumped at the Semakau Landfill daily.

If the waste can be used for roads, the amount dumped can be reduced by as much as half and the Semakau Landfill life-span extended by about 25 years.

The six-month trial will take place at a stretch of Tampines Road just outside a heavy-vehicle park.

Laboratory tests have been done, but will it work in practice?

Lim Bok Ngam, LTA's deputy CEO for infrastructure & development, said: "The main thing we are looking at is the longer-term strength (of the road) because the materials that we use today, we know that most new roads constructed can last 20-30 years before any major repairs are required. For this material, the life span of the road may be slightly reduced.

If the pilot is successful, LTA's long-term aim is to increase the amount of recycled materials in roads to 70 per cent from the current 25 per cent.

- CNA/ir