Work to replace road signs and markings and create a revised road layout on the London-bound carriageway, near Heathrow Airport, began at 2200 GMT on Monday.

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The M4 eastbound, between junctions two and three, will be closed overnight for three nights from Tuesday, and again for four nights from 22 November, to continue work on road signs and markings.

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Buckinghamshire has selected sites that are "low-risk" and has added solar road studs, extra signs and road markings.

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Mapping nearby features, spotting road edges and lane markings, reading signs and traffic lights and identifying pedestrians is done using a combination of cameras, radar and lidar (which works like radar, but with pulses of light rather than radio waves).

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The upgrade would include new block paving, resurfacing of the existing carriageway, new traffic signs and road markings, the council said.

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They are snapping pictures every 30 feet recording road signs, lane markings and anything else a driver might need to know.

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Road markings and signs are already being put in place ahead of the new limits coming into force on 8 April.

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Lanes have been marked by road markings and traffic signs.

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