The explanation comes after the road at Whytescauseway to the junction with the High Street was closed on Wednesday morning.
Openreach Limited has now confirmed that the work is associated with the rollout of ultrafast broadband in Kirkcaldy.
The move comes after local traders and some residents voiced their concerns at the disruption.
An Openreach spokesperson said: “We’re building a new, full fibre network in Kirkcaldy to give residents access to our gigabit-capable broadband. It will future-proof the local network for decades to come and bring multiple benefits to people and the local economy.
“Wherever we can, we use our existing duct-and-pole network - and that generally helps us to avoid digging and disruption.
"But in order to include some properties in the upgrade, we may need to carry out roadworks or put up new poles. In this case, we need to unblock an underground duct so it can be used in the upgrade. We’re sorry for any short-term disruption while works are carried out.
“Local people in many Fife communities are likely to spot an increase in Openreach activity as we continue work on the ground.
"Towns like Dysart, Kinghorn and Ballingry are in our investment plan, and early works are under way in Burntisland, with the main build there due to start this summer.
“Our new network has reached its first 2,000 homes and businesses in Kirkcaldy, with a third already ordering some of the UK’s fastest, most reliable broadband from their providers.
"People can check plans for their postcode at www.openreach.com.”