THEY are the green smiley faces across the roads of Hertfordshire that tell motorists they are driving safely.

But now there have been calls to see if they can be used to make the roads even safer.

In the past 12 months more than 150 Speed Indicator Devices have been installed at roadside locations across the county.

Every motorist that passes within the speed limit sees a smiley green face. But those motorists who drive too fast see a sad red face.

The ‘smiley face, sad face’ scheme is designed to make motorists think about their speed on potentially dangerous roads.

But now investigations are to be made into whether the data collected by the devices could be used to trigger further speed enforcement or road safety work.

At any one time the roadside devices store data on the last 200,000 ‘passes’ by vehicles.

And it’s that data  – it has been suggested – that could be used to provide information on roads where speeding is most prevalent.

Highways Committee chairman Cllr Ralph Sangster told members that the data collected was not sustainable in itself in terms of analysis or enforcement action.

He said the simple Doppler system was intended only to be indicative to motorists who were travelling at speed.

And the committee heard how the devices could pick up the same vehicle several times on its approach and could be fooled by cars turning or travelling in the opposite direction, But Cllr Michael Muir suggested that downloaded data that highlighted a high instances of ‘speeding’ vehicles could valuably indicate to police where they could go with a hand held device.

And at the meeting of Hertfordshire County Council’s Highways Committee (May 9) it was agreed that officers would now look at the cost – in terms of finance and time – of recovering data from the Speed Indicator Devices.