A major route into the centre of Ipswich closed for repair work since Tuesday, causing misery for rush-hour commuters, is set to reopen on Saturday.

Spring Road has been closed in both directions between Cauldwell Hall Road and St Helen’s Street since 8am on Tuesday after a depression was found in the road on Wednesday last week.

But officials at Suffolk County Council last night said the road is expected to reopen at around noon on Saturday after engineers found the problem had been caused by “poor ground conditions” and a “failure of historic reinforcements” in the area.

They explained years of “intense vehicle activity” had accelerated the corrosion of the ground, made of a softer and sandier material, below the surface.

Urgent repair work will now be carried out.

On Monday night, highways bosses moved to defend the eleventh hour decision to close the road after they were faced with questions over why it was cut off to commuters during one of the busiest travel periods.

They said the safety of the public was their “paramount concern”, insisting it was vital the road was repaired to a safe standard before reopening.

But scores of motorists contacted the Ipswich Star to voice their anger over the closure, with one branding it a “ridiculous planning” decision.

Compounding the misery for commuters, temporary three-way traffic lights became stuck on red for a period of time, forcing motorists to decide when it was safe to cross the junction.

A nearby road closure heading into town, where Woodbridge Road turns into Argyle Street, exacerbated travelling woes.

Yesterday a spokesman for the county council said they “realised the inconvenience” but insisted work was carried out “as quickly and efficiently as possible”.

After the discovery on Wednesday last week, results of a camera survey on Saturday proved inconclusive. It was announced Monday night that Spring Road would close at 8am on Tuesday.

A diversion was put in place through Cauldwell Hall Road, Foxhall Road and Grove Lane before it emerged on Wednesday engineers had identified the cause and will work to reopen the road by noon on Saturday.

The county council spokesman said: “We can confirm that Spring Road is expected to reopen to all vehicles around midday on Saturday, earlier than expected.

“After an ongoing investigation in to the depression on the road, our contractors confirmed (on Wednesday) afternoon that the cause of the defect is due to poor ground conditions and a failure of historic reinforcements of the area in question.

“With years of intense vehicle activity, this small section of the carriageway has begun to fail.

“Now that we have confirmed this as the defect, our contractors are intending to complete this repair using more robust materials. This will begin immediately and be completed before the end of the week.”

He added: “We realise the inconvenience this has caused those travelling into Ipswich, but want to assure them that this necessary work was carried out as quickly and efficiently as possible.

“The contractors have worked tirelessly in identifying the cause and subsequently planning a quick turnaround for resurfacing, allowing a safe route for those travelling along this road in years to come.”