Gulf Construction Online - New road to ease traffic congestion

Compaction & Paving Equipment

Dynapac pavers at work on the Emirates Road expansion project.

New road to ease traffic congestion

01 September 2005

Ajman-based roads contractor Darwish Engineering has recently taken delivery of two purpose-ordered Dynapac compaction rollers from local supplier Inma, for paving duties on the wearing course of the Emirates Road extension in Ajman.

The tandem-driven Dynapac CC 322 and pneumatic rubber-tyre CP 271, join a fleet of Dynapacs working on the 20 km extension.
The extension, together with the Sharjah extension, will reduce traffic through the Emirates’ cities by up to 40 per cent. It has been estimated that on completion of the Ajman extension, together with a new 14.4 km section around Sharjah, traffic travelling from Dubai and onto Ras Al Khaimah (RAK) will be able to by-pass the cities of Sharjah and Ajman, reducing traffic through Sharjah by up to 40 per cent
Darwish started work on the Ajman extension from the Ajman/Sharjah border to the RAK border in August 2003.
The Ajman section, which includes 2.5 m and 1.2 m hard shoulders in each direction, with a total road width of 15.8 m, also includes four interchange bridges.
From the start of construction, Darwish has relied on Dynapac compaction, drawing from its large fleet of Dynapac rollers. “As a company we have more than 30 years experience with using Dynapac’s machines,” says a Darwish spokesman. “Some machines dating back to the 1980s are still actively working today.”
For compaction of the project’s 40 cm-thick sub-base Darwish used Dynapac CA250 single drum rollers to ensure 98-99 per cent mod proctor compaction; using rollers from its fleet of 14 CA 251 and CA 250.
Darwish also used the Dynapac CA 250 for compaction of both 10 cm wet mix layers before laying the two seven-cm-thick wearing courses and introducing high-frequency compaction techniques with the Dynapac CC 322.

High frequency compaction
The use of high frequency compaction techniques developed by Dynapac at its International High Comp Centre in Sweden has proved that thin layer compaction is more efficient with a circular vibration (low amplitude, high frequency) roller than the traditional oscillating machine.
Traditional rollers require more passes and have an increased possibility of crushing aggregates, says a Dynapac spokesman.
Dynapac’s hydrostatically-driven tandem roller can be initially set on a high amplitude and low frequency setting to achieve the required density and depth of compaction in the thicker base and binder layers.
The roller is then switched to low amplitude, high frequency setting to complete the compaction of the upper part of the thicker layer, and compact the final overlaying wearing course.
This technique eliminates the tendency to cover compact thinner layers where over compaction increases the risk of crushing the aggregates.
Initially using the Dynapac CC 322 tandem roller in alternative static and vibratory modes, the contractor used the Dynapac CP 271 pneumatic-tyred roller and a number of older Dynapac pneumatic-tyred rollers to ensure a smooth finish.
“Between 12-16 passes were made by the tyred-rollers over a maximum 40 m,” says asphalt foreman, Ezzedine Taieb Hichri. “To do longer would mean the asphalt had cooled before being correctly compacted.”
The Dynapac CC 322 – an 8.3-tonne class of tandem roller – features a 1,680 mm drum width and 1,120 mm diameter – and has a capacity to compact asphalt up to 1800 sq m/h.
The CP 271 pneumatic-tyred roller – used together with the CC 322 tandem roller, for surface sealing – features a total of nine rubber-tyred wheels giving a rolling width of 2,350 mm and a maximum wheel load of 3,000 kg/tyre.
The first phase of Sharjah’s plan to upgrade its Ring Road to form part of the Emirates Road will feature construction of a three-lane dual carriageway, starting at Sharjah’s Industrial Area Number 15, turning north west and parallel to the Sharjah – Ajman border where it will link with the new Ajman extension.
The initial section will include four grade separated interchanges to allow free-flow traffic along the Sharjah Ring Road and provide continuation of the Emirates Road from Dubai. On completion, the Emirates Road will include a 30 km ring road around the city of Sharjah.