The Highways Agency this week announced that it intends to complete all planned welding repairs to the troubled M4 Boston Manor viaduct in west London by mid-October.
Work stopped on the affected section of the Olympic Route Network during the Olympic and Paralympic Games, and the Agency restarted welding repairs last week.
It hopes that within the next month it will remove the existing 7.5t weight limit, first imposed in April following the discovery of cracks in welds.
“We’re taking an ultra-cautious approach to the repairs,” said a Highways Agency spokesman.
Boston Manor viaduct is a 965m long, 21 span steel viaduct carrying the M4 between junctions two and three.
Discovery of the cracks led to the dramatic closure of the motorway just days before the start of the London 2012 Games in July after repair work caused a crack in a “highly stressed” area to widen.
This section was rapidly repaired ahead of the Olympics using steel compensation plates, but the Agency suspended further repairs to avoid closures during the Games.
Five of the 64 original defective welds must still be repaired - three on the box girder sections and two on the plate girder sections.
But the Highways Agency spokesman said that, while engineers did not believe a similar problem would occur while repairing the other cracks, no guarantee could be offered that it would not.
The repairs are designed to last for the remaining 60 years of the structure’s 120 year design life. However, transport minister Mike Penning told NCE in July that the viaduct would be replaced sooner.