Transport for London has invited bids to take over the running of the London Overground from November 2016.
First launched in 2007, the service carries more than a 135 million customers a year and is set to grow next month when TfL takes over the routes running from Liverpool Street station to Enfield Town, Cheshunt (via Seven Sisters) and Chingford.
Bidders hoping to replace current operator London Overground Rail Operations Ltd (LOROL) have until l mid-May to register their interest.
TfL says the new contractor will be responsible for helping to deliver higher frequency services, a continuing programme of station upgrades and possibly an all-night service at weekends and additional services to Barking Riverside in 2019.
Jonathan Fox, TfL’s Director of London Rail, said: “This is a very exciting time for London Overground as we expand our fleet and serve new parts of the Capital.
“At end of May, we will take over the running of local services out of Liverpool Street station to north east London, which will also come under the new concession.
“Customers can look forward to new air-conditioned walk-through trains, which will start operating from 2018, and will benefit from stations being staffed at all times when trains are running.
“This bidding process is vital to ensure London Overground’s performance is maintained and improved to make services even better for our customers.”