PHD has made the list for the three-year contract along with Carat, MediaCom, Mediaedge:cia and Starcom.
The contract includes advertising for the Underground, buses, congestion charging, road safety, river services, taxis and licensed cabs, Victoria coach station and road traffic enforcement.
TfL is hoping to reduce the premium it pays in buying regionally specific airtime compared with national airtime. A decision is expected by September.
If you have an opinion on this or any other issue raised on Brand Republic, join the debate in the .