ROADS THAT FAIL ‘ROUGHNESS’ TEST TO BE DISMANTLED
>> Highway contractors will have to dismantle and reconstruct their roads if the surfaces do not pass International Roughness Index (IRI) tests, Department of Highways (DOH) chief Thanin Somboon said yesterday.
“The testing methods will apply to existing highways as well as upcoming projects,” he said.
The IRI is typically used to measure smoothness of roads, most commonly those made from asphalt or cement. Introduced in 1986, it has become the most popular road roughness index in the world.
The process involves using wheeled machines, called walking profilers, to measure the roughness of the road surface. These profilers are manually operated by trained engineers.
“We are awaiting the delivery of 18 walking profilers worth around 2 million baht each, which have been ordered to conduct IRI testing on our highways,” Mr Thanin said. “They will raise public safety standards to meet accepted international standards.”
IRIs are normally measured in inches per mile or metres per kilometre. A safe figure for asphalt surfaces should not exceed 2.0 m/km, while concrete surfaces should not go above 2.5 m/km.
Mr Thanin said testing has so far only been conducted on newer DOH highways which are under construction.
“IRI testing conducted on our new projects have revealed an average of 1.66 m/ km, which is an impressive result for concrete surfaces,” he said. “We would like to see similar results in the future.”
On the progress of the mentioned new project, Mr Thanin said a provincial highway from Bang Pa-in in Ayutthaya to Saraburi, with its terminus in Nakhon Ratchasima, is now around 32% complete.
Construction of the 196km route has been valued at around 76 billion baht, according to DOH reports.
He said land expropriation should be settled “soon” so construction does not have to halt abruptly.
“We project that once it is complete, around 20,000 vehicles will use this route daily, most of which will be private vehicles,” Mr Thanin said.
He said another provincial highway, a 96km route from Bang Yai in Nonthaburi to Kanchanaburi valued at 49 billion baht, is around 6% complete.
“Expropriation was initially estimated at 5.4 billion baht, but the land involved proved far more costly, and that figure has now risen to 19.7 billion baht,” Mr Thanin said.