Parents say high school pupils in Penwortham have been left "stranded" after buses failed to show up at home time.
Parents of pupils at Penwortham Girls' High School said their children were only informed that Stagecoach services 2, 2A and X2 were not running to the Hutton, Longton and Much Hoole areas when a driver travelling in the opposite direction got out to tell them their wait was futile.
Instead they say they were told to catch a bus in the opposite direction to Preston Bus Station, then get another to their home location.
The changes have been made because of the temporary closure of Liverpool Road at Howick.
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One parent said: "There are three high schools within Penwortham and many of those children were left stranded unable to get home from school with no buses running. Also, many of these children then had to travel in the wrong direction towards Preston to then travel back towards their home, this is in the dark, some alone, in a busy city having to take a route they are unfamiliar with.
"I am horrified that as a reputable company Stagecoach and the council have not notified the three schools to enable parents to make alternative arrangements due to the road closures. I am further disgusted that the only way my daughter found this out was by a bus driver going in the opposite direction getting off his bus and telling her.
"My daughter was unsure what to do and considered walking home down the side of a dual carriageway."
Another parent said: "My children got home at 4.40pm in the dark. I know the new road layout is causing problems for traffic but we have had no prior warning of this happening. School has not been informed so were unable to inform parents.
"This is ridiculous to ask kids to catch a bus into town ,which is the opposite direction to home, and then catch another bus home. It's dark and cold and I for one do not want my girls making this journey regularly.
"I have spoken to a number of other parents who feel the same and are very angry about the lack of communication with us by Stagecoach."
Stagecoach has been approached for comment.
The company announced diversions to the services on its website on November 27.
It says from December 2 to 22, the 2, 2A and X2 during peak times - 7am to 9.30am and 2.40pm to 6pm - services will be diverted in both directions operating via the New Bypass, A582 Golden Way, then back onto Liverpool Road (by River Ribble) then normal route towards Preston. Buses will not be serving Howick Cross.
Outside of peak times, services will be diverted in both directions operating via the New Bypass, Millbrook Way, Cop Lane then back onto Liverpool Road (from Penwortham Library) then normal route towards Preston.
Penwortham Girls' High School, Penwortham Priory Academy and All Hallows High School have all been approached for comment.