Work is in progress on the widening of a 25-km-long highway near Dammam. The highway, currently a dual carriageway (two lanes in either direction), is being upgraded to include eight lanes, four lanes in either direction.

Khodari, one of Saudi Arabia's leading contractors, is currently using a fleet of 13 compaction rollers, including 10 Dynapac units, on its 2.3 km section of the project to widen the Dhahran to Abqaiq road. Khodari has more than 15 Dynapac rollers in its entire construction equipment fleet.

This highway is one of the busiest in the Eastern Province, linking this important industrial and oil producing region with highways to the capital Riyadh and the Gulf states of Qatar and the UAE.

Khodari's section of the scheme includes road widening as well as construction of two bridges, which will form interchanges and allow traffic to leave and enter the road from the Dammam Second Industrial City and the King Fahd military base and hospital.

The industrial city accommodates 113 factories, with a further 160 under construction. At present, trucks leaving the city must filter onto the highway, which causes delays and accidents. The same scenario also happens 2 km away at the junction with the military base and hospital.

Because of the number of trucks using this highway, the Ministry of Communications has stated that the new lanes as well as bridge access roads should have a thicker aggregate base, 20 cm, compared with the normal 12 cm. This also means that contractors are relaying the original surface of the highway once the new lanes have been completed.

The road construction proceeds first with backfilling and embankment excavating. As the area is generally uniformly flat, backfilling is kept to a minimum.

The next stage involves two 15-cm-thick sand sub-grade levels, which are compacted by a team of Dynapac rollers to a 100 per cent density, with all passes vibratory.

A 20-cm-thick aggregate base is laid on top, and then a 13 cm layer of asphalt, which includes 8 cm binder and 5 cm of wear course.

All the new road lanes and bridge access roads are 3.2 m wide, while the shoulder has a width of only 2 m but has the same depth of courses.

According to Hossam Gomoah, project manager for Khodari, the compaction rollers typically do around six vibratory passes on the subgrade and aggregate courses, with seven passes required on asphalt.

Khodari has four of the latest Dynapac CA302D vibratory compactors, as well as four CA251 units, two CA251Ds, one CC422 machine and two CP271 tyred-rollers working on this project.

Only recently introduced to the Middle East, the CA302D is powered by a Cummins diesel engine, has a drum width of 2,130 mm and an operating mass (CECE) of 12,600 kg.

"Usually we have at least five units, including the four CA302D machines working in tandem on sub-grade compaction duties," says Gomoah. "Following behind the paver, we normally use six compactors each doing six vibratory passes over a length of 150 m."

The CP271 tyred-rollers will then follow behind and compact a further four passes.

The entire 25 km-long project began in July 2001, and Kodari estimates it will finish its section, including the two bridges and access roads, by mid-2003.

All the compaction machines were supplied by local Dynapac dealer Medco, which has been the Dynapac dealer since 1967.

Medco claims 50 per cent of the total heavy roller market in Saudi Arabia.