Dubai-based developer Emaar Properties has extended the operation and maintenance (O&M) contract for the Dubai Downtown trolley system with the UK’s Serco.

The extension covers a period of three years.

Serco’s participation in the project began in August 2014 when it was appointed by Emaar Properties under an early operator involvement contract to assist with the design phase.

The contract extension helps Serco assert its position as the region’s “leading provider of high quality transport operations and maintenance services,” David Greer, chief executive at Serco Middle East, said in a statement.

The initial O&M contract was awarded to Serco in 2015. The new agreement extends the contract period to up to 2019.

The total cost of the project is AED500m ($136m) and will extend for a total length of 7km when completed.

The Dubai Downtown trolley system is a tramway that uses a fleet of double-deck open-top trams to provide transport services in Dubai’s Downtown development complex, which includes the emirate’s key tourist attractions such as the Dubai Mall, the Dubai fountain and Burj Khalifa.

Built by the US’ TIG/m, the trams are powered by fuel cells and equipped with batteries to recover regenerated braking energy.

Serco operates the Dubai Metro, tram and the Palm monorail.