Residents say motorists drive over the line markings to the wrong side of the road.

The Hills Shire Council will install 100 metres of the bars from the Orange Grove roundabout to the curve in the road near the Castle Hill Adventist School.

Residents had complained that visitors parked on both sides of the road when they were dropping off and picking up their children from the school. They said this made it hard for two lanes of traffic to move in either direction without crossing the centre line.

Peter Bell told the Hills News last month that parking should not be allowed on either side of Cecil Avenue from Terminus Street to Orange Grove.

Mr Bell said residents had given up driving up their own street.

``There's no other way to get out besides driving along Orange Grove to Crane Road, and that will get worse when Old Northern Road is [partially] blocked off to traffic,'' he said.

Other residents said motorists parked across driveways, which blocked the way for people trying to drive from their homes.

The council said the road was 10 metres from kerb to kerb and was considered wide enough to maintain two-way traffic movement between parked cars.

But the council conceded that some motorists did drive across the centre line, particularly when they were heading towards Terminus Street.

To ease traffic jams and increase lane space, the council will replace non-enforceable signs outside the school with signs that prohibit parking from 7am to 10am, and 2pm to 4pm on school days and 9am to 1.30pm on Saturdays.

The no-parking zone will be extended by 10 metres east towards the roundabout.

But Mr Bell said this would simply ``shift the problem of congestion towards the roundabout''.