Rabbits are behind three months’ of road works outside Stanstead Airport after burrowing three-metre deep holes under ground.
A void under the M11 at Girton was discovered in September and caused months of disruption on the stretch of motorway that is used by more than 40,000 drivers daily.
Highways England poured 1,200 tonnes of filling material into the hole and undertook drainage repairs, sheet piling installation and environmental works to ensure this does not happen again.
A spokesman for Highways England said: “It was originally caused by rabbit activity and burrows undermining the structure.
“This unsettled the embankment and the voids came from water damage. The rabbits started it but then water got into it.
“We corrected that as soon as we could.”
The affected lane reopened on Thursday (November 16) but the hard shoulder is closed and a temporary 40 mph speed limit is in place while rabbit netting and top soiling is replaced.
Highways England project manager Karl Brooks said: “Safety is at the heart of everything we do at Highways England, and once we realised the extent of these voids underneath the M11 we moved quickly to get it repaired.
“While we want to limit the impact that our work has on people’s journeys, these voids did need to be repaired with haste and we needed to ensure that there would be no more surprises.
“We have worked with our partners to minimise the impact this work has had, and are pleased that we are now able to fully re-open the M11 to traffic at Girton.”