The costs include hiring consultants to draw up plans for where the roads would potentially go, as well as lengthy public consultation to see if there were support for them.
The road from the A48 at Sycamore Cross to the M4 at Junction 34 proved highly unpopular as concerns ranged from houses getting knocked down to ancient woodland felled.
That road has cost £462,632, which was funded by grants from the Welsh Government.
The road bypassing Dinas Powys however was generally supported by the public, and was part of a wider project to improve transport infrastructure in the village like better bus shelters and cycling routes. The bypass could have cut congestion in Dinas too, a current problem.