Contractor BAM Nutall set up a 30-metre exclusion zone around the nest so the birds weren’t disturbed, and the adults have now successfully reared their four chicks.
The nest was initially observed in April, and over the next three months the pair worked to raise their offspring.
Engineers redirected construction traffic to avoid the area and the works programme was rearranged to ensure no delays resulted.
After a nervous wait for all concerned, the chicks successfully fledged at the beginning of July.
Man charged after £14.5k of cannabis seized at drug factory in Luton home
Plans to protect Luton parks being drawn up because council is 'ignoring' its own local plan says councillor
Picture shows aftermath of field fire in Sundon Park Road in Luton
Youths spotted deliberately damaging fencing along the Luton to Dunstable busway
Luton's Wigmore Park needs your vote in contest to find the nation's top green spaces
Andy Graham, spokesman for BAM Nuttall, said: “It has been like watching our very own live edition of Springwatch.
“The birds have captivated everyone working in the area, and there has been much interest following the kestrel family.
“We had to remain vigilant to the birds, as they gradually became more and more acclimatised to the works taking place around them.
“The chicks could be clearly seen as they grew bigger, waiting for food from their hard-working parents.
“We were thrilled when all the offspring left the nest.”