Gulf Construction Online - Dynapac paves major road link in Ankara

Turkey

A Dynapac paver works on the ring road.

Dynapac paves major road link in Ankara

01 September 2002

Turkish construction company Onur, which holds the maintenance contract for the ring road surrounding capital Ankara since the road opened in 1997, carries out work using its fleet of construction equipment which includes six Dynapac pavers and compactors.

The 127-km-long Ankara peripheral highway opened in 1997 and was constructed by a Turkish/US joint venture between Enka and Bechtel. During construction of the highway, Onur was the main sub-contractor, responsible for paving and earthmoving.

The company also works regularly for Turkey's General Directorate of Highways, and this involves maintenance and repair work for all of Ankara's municipal roads.

Currently, the company is repairing sections of the ring road to the south of Ankara. A typical work team will usually comprise a milling machine, a paver - in this case a Dynapac F 14C - and at least two compactors.

The highways department checks the ring road on a regular basis and specify when and where the road needs to be repaired, as well as the milling depth.

For most repair work, milling is usually to a depth of between 5 and 12 cm, with working widths up to 2 m. The road has 6, 8 and in some sections 10 lanes, all of which are 3.5m wide.

According to Sertac Karan, mechanical engineer for Onur, the main problem for the road apart from the heavy traffic volume, is the fact that underground water causes the sub-base to move and this causes cracks to appear on the road surface.

The Ankara Ring Road comprises a 28-cm-thick sub-base, a 22-cm layer of concrete treated bitumen (CTB), a 12-cm layer of asphalt treated bitumen (ATB), an 8-cm layer of asphalt binder and finally a 5-cm asphalt-wearing course.

Average repair work lengths are usually between 50 and 150 m, with work generally completed in one day, weather permitting.

Once milling has been completed, the paver will lay a new wearing course to the required depth, and usually in 4-m-wide sections.

The paver has a maximum working width of 8 m, which equates to more than two lanes on the Ankara Ring Road. The unit has a hopper capacity of 12.5 tonnes, and can easily pave 500 tonnes/hr.

A fleet of 14 cu m capacity trucks supplies the paver, and usually carries approximately 12 cu m of asphalt which weighs nearly 26 tonnes. The Dynapac F14C will make two paving passes if the repair work requires a new asphalt binder as well as a new wearing course.

The asphalt comes from one of Onur's own asphalt batching plants in the Ankara area, the largest of which has a 400tonne/hr capacity.

Once paving has been completed, the company will compact the asphalt; three passes with a vibratory compactor and then three to five passes with a tyred roller. "One final non-vibratory pass is usually required just to settle the surface," says Karan.

Onur says it completes approximately 20 km of repairs a year on the Ankara Ring Road in this way.

Nothing is wasted on this on-going project, the old milled asphalt is reused by the General Directorate of Highways for rural roads.