TfL spent £5.4m on consultants looking at London roads, unions claim
Unions have accused Transport for London (TfL) of "wasting" millions of pounds on consultants.
Unison and the Transport Salaried Staffs Association (TSSA) said TfL's consultants earn up to £2,700 a day.
The unions alleged TfL were keeping consultants on the roll while laying off regular staff to meet its £2.4bn efficiency savings target.
TfL said it needs "specialist skills" but denied consultants were employed at the expense of full-time staff.
In one year Congestion Charging and Traffic Enforcement spent about £5.4m on consultants, figures released by the unions show.
"It's the economics of the madhouse to pay consultants millions while loyal and experienced staff are being sacrificed to fill a black hole in the books
Dave Prentis, leader of Unison, said: "If one small department is wasting £5.4m on consultants each year, then the total spent by TfL must be colossal.
"TfL cannot be serious about saving money if it can afford million-pound spending sprees on consultants."
TSSA general secretary Gerry Doherty said: "It's the economics of the madhouse to pay consultants millions while loyal and experienced staff are being sacrificed to fill a black hole in the books.
"We want to see all consultants shown the door before we even talk about staffing levels with TfL."
A TfL spokesman said: "It is completely wrong to suggest that TfL is wasting millions or employing consultants at the expense of full-time staff.
"However, we are investing billions to deliver the best possible service and upgrade the transport network, which sometimes demands temporarily engaging specialist skills not otherwise available amongst our staff."
TfL added it has "significantly reduced" the number of consultants as part of its savings target and stressed that consultants are let go as soon as the projects they work on are completed.