Chicago Transit Authority officials want to make it easier for travelers to use their cellphones in its underground subway tunnels.
The agency said Wednesday that it's researching how to improve its network so passengers can get "continuous, reliable wireless service" in the more than 11 miles of underground tunnels and stations.
Two of the transit system's train lines -- the Red Line and the Blue Line -- have partial underground operations.
The CTA already owns and leases its subway cellular network to six major wireless providers.
Mayor Rahm Emanuel says the wireless access is important, especially between the city's downtown and Chicago's O'Hare International Airport, so travelers can move around the city efficiently and productively.