Motorists were stuck in queues at temporary traffic lights on the A428 near East Haddon yesterday morning as vehicles diverted as a result of a fatal accident on the M1.
Several drivers contacted the Chron to complain that the lights appeared to serve no purpose as there seemed to be no workers at the scene.
However, Anglian Water, which put the lights in place, said the traffic measures were in place because workmen were working below ground.
A spokesman also added that the roadworks were removed on Tuesday afternoon.
He said: “I can assure you that the workmen were definitely there and they may have been hidden from view underground.
“We apologise if they caused traffic to build up, exacerbated by traffic diverted from the M1.”
The reason for the work is a major project to replace pipes between Ravensthorpe Reservoir and Long Buckby.
Anglian Water said the work will finish in February next year but that no more will be carried out until after Christmas.