The Delhi government has missed a second deadline for installing global positioning systems in buses and sought more time from the High Court which granted it four months to finish the task.

Appearing before a bench headed by Justice A K Sikri, the counsel for the government sought more time to install GPS in the buses saying it would not be able to complete the task by August 15, the deadline fixed by the court, as there was paucity of the instruments in the market.

After hearing his argument, the Delhi High Court gave the government four more months to install the system in all buses.

GPS bus tracking system uses satellite technology and advanced computer modelling to track vehicles on their routes.

Each vehicle is fitted with a satellite tracking system.

Taking into account the actual position of the buses, their intended stops and the typical traffic patterns, the system can estimate vehicle arrivals with a high degree of accuracy.

The court had earlier on February 4 extended the time for installing the system and fixed the August 15 deadline.

The court was hearing a matter in which it had taken suo motu cognizance following an accident involving a blueline bus in October 2008 in which eight people were killed at Badarpur area.

The court had directed the phase-out of blueline buses, after which the city government launched low-floor buses last year. It had also directed the city government to frame guidelines for drivers, bus operators and owners.

The GPS system in the buses supports details such as current locality, expected arrival timing at the specific bus-stop and others.