Two large sections of south and east Bristol are set to become 20mph zones early next year – an idea that could eventually spread to the whole of the city.

The councillor in charge of the city's transport system, Jon Rogers, wants to restrict the speed of drivers in two large parts of Bristol in a £250,000 bid to improve safety and reduce pollution.

The south zone includes Southville, Bedminster and Windmill Hill, while the east zone includes most of Easton, Whitehall, Redfield, The Dings, Barton Hill and St Paul's.

And the roads covered will include some of the city's busiest roads, including parts of Fishponds Road, Stapleton Road, Ashley Road and Church Road in the east zone and Ashton Road, East Street, West Street and North Street in the south.

Mr Rogers plans to introduce the zones in the spring, and has said the whole of Bristol could eventually be included.

The zones will not involve the introduction of any speed cameras, or physical traffic-calming features such as speed humps or chicanes.

Instead there will be standard 20mph signs at the entry points, smaller speed signs on lamp-posts and road markings to show the speed throughout the zone.

Mr Rogers says the evidence from cities like Portsmouth shows that people regulate their own speed, but if this does not happen he would discuss tougher enforcement with police.

Drivers caught breaking a 20mph limit face a speeding ticket in the same way as for breaching any other, higher limit.

But opponents claim 20mph limits are unenforceable without expensive cameras, driving at that speed in modern cars is unrealistic and could cause more accidents.

Originally, highways officers only wanted to include a number of specific streets in the 20mph scheme.

Consultation in September showed residents were keen on the zones, and actually wanted more streets included.

So Mr Rogers rejected his own officers' and police advice by expanding the zones beyond the early proposals to cover whole sections of the city.

Now the eastern zone only excludes Newfoundland Street to the M32; Easton Way to Lawrence Hill roundabout and Church Road from the City Academy to Old Market roundabout.

The section of Church Road between the Academy and St Georges Park has already had 20mph calming measures put in.

The south zone will not include the A370 Clarence Road and York Road.

Residents the Bristol Evening Post spoke to in the pilot areas had mixed views.

Some felt anything that dropped the speed of traffic was a good thing while others felt drivers would simply ignore the limits.

Campaign group The Association of British Drivers said they would "criminalise" safe drivers.

Chairman Bryan Gregory said: "Our concern about 20mph zones is that they aren't enforceable over a large area.

"They will simply criminalise drivers who drive perfectly safely.

"It is one of those issues where the council thinks they need to be seen to be doing something.

"It's difficult for drivers to stay at 20mph in modern cars, you have to keep it in third gear and keep your eyes on the speedometer.

"You could be skittling over pedestrians at 20mph that you would have seen if you were going 30mph.

"It could make the situation worse.

"It sends the wrong message to pedestrians; they need to take care of their own safety."

But another campaign group, 20's Plenty For Bristol, has backed the slow-down.

Members organised an online petition with around 500 signatures supporting the idea.

Bus company First have given a cautious welcome to the zones. Bristol, Somerset & Avon commercial director Simon Cursio said: "The proposals put forward by the council are interesting, and in some places will be helpful reducing the likelihood of road traffic incidents, however the plan to include a number of main routes in the 20mph zone should be carefully considered before it is given final approval as this could have a significant impact on traffic flow in the city.

"We will discuss the impact of the proposals with the council as part of the normal consultation process."

During the initial consultation period, only four of 310 residents, businesses and organisations who responded objected.

Mr Rogers said: "Most comments focused on the fact that not enough roads were included in our original proposals.

"Many people wrote to say why not the whole of Bristol.

"So we have re-evaluated the proposal. What we have now are real areas where 20 is plenty and we will look at more.

"I want to see 20mph areas, rather than 20mph streets.

"We will be looking for communities outside the pilot areas to say 'include us'.

"The main arterial roads would likely remain 30mph or 40mph but certainly the residential and main shopping streets could be 20mph."

Formal consultation will be carried out as part of the issuing of Traffic Regulation Orders around Christmas, but further feedback from the public will only affect whether specific roads are included or not.

No one from the Avon and Somerset Police's traffic department was available for comment yesterday, but council reports say the force supports the idea of 20mph limits.

The first three 20mph zones were introduced in Sheffield, Kingston-upon-Thames and Norwich in 1991 and since then around 450 have been set up across the country.

Until 1999 specific consent from the Secretary of State was needed, but now local authorities do not need government approval.