Traffic lights planned as part of £53million upgrades to the A12 near Felixstowe may only be used at peak times, as highways experts explore using 'part-time' signals.

Suffolk County Council gathered more than 700 responses to a consultation in the spring on plans to upgrade the A12 between Seven Hills and Woods Lane in Melton, which proposed adding traffic lights at all junctions except for the Seckford roundabout.

But council road planners have said they are now keen to explore 'part-time' signals which would be on at peak-times to control traffic flows, and then turned off or with changed patterns at non-peak times.

Those are not currently used in the county but have proved popular in other areas, the council says.

The part-time signals are being considered at the Seven Hills, Foxhall, Barrack Square and Anson Road (Tesco) roundabouts. The A1214 junction already has lights, while the Seckford and Dobbies roundabouts are not planned to have signals.

Other developments planned include:

A free-flow offslip at the Seven Hills junction coming from Felixstowe

A bus-only slip between the A12 and A1214

Replacement of the pedestrian and cycle footbridge in Martlesham, with the addition of another close to the Brightwell Lakes development

Potential enlarging of the Barrack Square Adastral Park roundabout to make Gloster Road its own exit

Traffic lights and a pedestrian crossing at the Anson Road mini-roundabout onto Tesco and Beardmore Park in Martlesham

Increased and widened lanes at the Anson Road junction

Traffic lights at the Portal Avenue junction of the A1214 close to the A12/A1214 junction, and widened approach to the A12 there

A segregated free-flow lane at the Seckford junction northbound

Segregated pedestrian and cycle path on the new dualled section between the Dobbies and Seckford roundabouts

It comes as Suffolk County Council's cabinet is set to agree to put in an outline business case with a financial ask of the Department for Transport on November 9, with the bid to be lodged by the end of the month.

Detailed planning and development of plans will then take place over the course of 12 months, with another public consultation likely to be held in the autumn next year ahead of a final business case.

If approved, the two year construction period is likely to start mid-to-late 2023.

Richard Smith, Conservative cabinet member for economic development, transport strategy and waste, said: "If we did nothing we know that the traffic would get much worse, so the kind of things we are planning to do will keep the traffic moving and will give positive improvements with a new section of dual carriageway.

"Some of these roundabouts will benefit, the traffic flow will benefit, from having traffic lights. But we intend to have those as part time, mostly peak-time periods or occasionally with very heavy traffic they can be switched on, but all of them will be co-ordinated by the most up-to-date software we have."

The council said modelling indicated that the scheme provided a good return for the money invested, but opted not to extend the scheme further north than Melton because the benefits significantly reduced.

If approved, the scheme would require around 15% of funding to come from local sources – about £8m – which could include housing developer contributions or the county council's capital budget.

A £10m risk allowance has been built into the project costs.

According to the council, current traffic levels on the A12 are close to pre-pandemic levels, while future traffic modelling has indicated volumes are set to increase by a quarter by 2040 near Melton and Foxhall, while Martlesham junctions will have nearly 47,000 vehicle movements per day in the next two decades.

In addition, the team believes that while there will be some biodiversity impact from widening approach lanes, the overall will be a slight biodiversity improvement as vehicles will not be idling at snared up junctions as much.

Keith Welham, transport spokesman from the opposition Green, Liberal Democrat and Independent group, said investment needed to shift more towards cycling, bus and pedestrian provision, adding: "Widening roads and speeding up traffic through junctions will result in more traffic and produce congestion and safety issues elsewhere.

"We should be spending £40m-60m on measures to attract people away from their cars – to improve travel for all road users without further damaging our environment."