Strathclyde Partnership for Transport (SPT) said the latest stage of its Glasgow subway modernisation programme will require the suspension of subway services for four weeks from Saturday July 2, 2016.
Subway services are planned to resume on Monday August 1.
During the subway closure, a replacement bus service will be provided for subway passengers.
The bus service will follow subway routes with extra direct services to the city centre from key stations.
Bus services will be every five minutes at peak times and every 10 minutes during off-peak.
SPT has a flat fare structure for the replacement bus service so all passengers will pay £1 for a single journey, £2 for a return and £2.50 for an all-day ticket.
Child fares will be 50p single and £1 return.
SPT chairman Jonathan Findlay said: “To date, SPT has achieved all of the modernisation works without any disruption to passenger service which is a considerable achievement.
“We have now reached a crucial stage in the modernisation plan that requires us — for reasons of safety for everyone involved — to suspend services for a short time during July.
“We apologise for any inconvenience to all our passengers but our full replacement bus service will mean that they can still get to where they want to go.
“All our passengers are encouraged to turn up at their designated stop, allow a little longer for the journey, and leave the rest to us.”
SPT said July was chosen for the closure because summer is the quietest time on the Glasgow underground.