Bridgend, Merthyr Tydfil and Rhondda Cynon Taf CBCs have signed a 15-year partnership with Capita Symonds in the creation of a new company - Capita Glamorgan Consultancy (CGC) - which is jointly owned by Capita and the three authorities.
It supersedes the Glamorgan Engineering Consultancy (GEC) - a joint venture between the three authorities which designed and managed local civil engineering projects.
The deal also safeguards the jobs of the 70 GEC staff who will TUPE transfer directly to Capita Glamorgan Consultancy with immediate effect.
Capita Glamorgan Consultancy is expected to deliver "significant savings" to the local authorities and create more than 130 new jobs over the next five years.
The councils also say it will provide a boost to the local community, creating a platform for long-term sustainable growth across the area through job creation, investment in a wide range of training schemes, and the development and implementation of regeneration and investment funding.
Capita Symonds has had a similar joint venture in place with four authorities in South East Wales for the last five years - Blaenau Gwent, Caerphilly, Monmouthshire and Torfaen.
Councillor Paul Cannon, cabinet member for economic development and housing at Rhondda Cynon Taf, said: "The introduction of a private sector partner will significantly enhance existing arrangements by providing additional flexibility and a much larger resource base.
"Capita Symonds’ proposals will enable us to obtain competitive rates for this important service area whilst benefiting from genuine expertise of local and national developments in highways and related engineering works.”
The CGC partnership comes under the banner of the Welsh Assembly Government’s Making the Connections strategy and subsequent Beecham Review for improvements in public services - a wide-ranging policy for transforming the delivery of public services across Wales.