Buses will continue to pick up and drop off from the external coach stands, which are opposite the rear of the Guild Hall.
The bus station will operate reduced hours from 5.30am to 6.30pm on Thursday and Friday, but will then be closed until further notice. Limited access to the building will be maintained for bus staff so that they can access rest and welfare facilities.
Andrew Varley, public transport manager for Lancashire County Council, said: "We have been working closely with operators to arrange the closure of the concourse at Preston Bus Station from the end of this week.
"The reasons for closing the concourse and the car park to the public are that, as with many of our services, we are already facing issues with availability of staff, and as the bus station can operate without the concourse, closing it will help to reduce any risk to our staff and the public from the spread of coronavirus.
"Closing the concourse also means that we have to close the car park as the only safe pedestrian access is via the concourse. At the same time, we have been working with partners to ensure their essential workers can continue to use the car park in a carefully managed way.
"Bus services are operating at much reduced levels, however they are still vital for essential workers who need them to get to work to continue to provide vital services, and these will continue to operate. We will be putting up notices to sign a pedestrian diversion as soon as we can.
"I'm grateful for the cooperation and understanding of the bus operators, and sorry for any inconvenience this will cause passengers, however hope people will understand the reasons we have taken this decision."
The county council has already closed the concourses at Accrington, Chorley, and Nelson bus stations.
CAR PARK ALREADY SHUT
The 600-space facility attached to the bus station, on Tithebarn Street, shut on Wednesday evening (25th March) - and it is not known when it will re-open.
It is understood that usage has fallen since the government’s new movement restrictions came into force earlier this week.
But people designated as “key workers” - who are often expected to continue to attend their places of employment – have criticised the closure.
Two employees at the Department for Work and Pensions (DWP) at nearby Duchy House – who did not want to be named - contacted the Local Democracy Reporting Service after being alarmed to see a notice advising that the car park would be shut.
Alternative arrangements have now been made for some staff – including continued use of the bus station facility for sopme key workers, as well as use of the B&M Bargains car park – but one of the workers said that the scramble for a solution should never have been necessary in the first place.
“They should have been not only keeping the bus station car park open, but making it free for us to use.
“We already feel up against it, because we are putting ourselves at risk by still going into the office as key workers,” the woman said.
A spokesperson for Lancashire County Council, which operates the car park, said: "We have contacted companies and services which have contracts in place for their staff to use the car park and arranged for limited and carefully managed use of the car park by some essential key workers."