A trial of live CCTV streaming on London's buses to help improve security has been dropped.
The live streaming could be accessed with hand held devices
The technology would allow CCTV footage to be beamed live from all buses to a control room or mobile devices.
Transport for London (TfL) had set aside £150,000 for a six-month trial but that has been shelved, BBC London has learned.
The cost of installing the system pioneered by the US military to all buses is estimated to be £20m.
TfL was approached by suppliers of security technology, Integrated Security Solutions Ltd (ISS), to test the system.
The technology was installed on an out-of-service London bus which drove around central London for four days in September.
"During the four days, we lost the signal for less than two minutes in total," said Jane Mason, of ISS.
She said the live images can be sent to hand held devices that could be carried by police officers.
"Once they are on the bus, if there's an incident above them as they are going up the stairs, they can see exactly what's happening live," said Ms Mason.
Mike Weston, of TfL, said it needed to study the benefits and cost implications of live CCTV streaming before going ahead with it.
He said: "We need to... make sure we understand what the cost implications would be, what the benefits would be and whether that money can be spent more effectively in other areas of security."