Oxfordshire County Council has faced criticism over the prolonged failure to open the £51 million Eynsham Park and Ride site to traffic.
Additional funding has been approved for the project, which includes a connection to the A40 and is intended to bring the facility into operation.
The original planning application was submitted in April 2021.
That December, the Department for Transport approved funding for the scheme, including access-road work and wider local-network improvements.
The 19-acre site, which provides 850 parking spaces, was finished in 2024.
It has since remained closed because inflation and a lack of funding prevented the construction of the road needed to connect it with the A40, including the necessary entry junctions.
The council previously argued that starting construction earlier had protected the project from subsequent increases in building costs.
At a recent meeting, cabinet members authorised a further £3.8 million for the A40 improvements.
The money will pay for the link between the park-and-ride site and the A40, allowing the facility to become usable.
Council leader Tim Bearder expressed regret over the circumstances and acknowledged that the council faced difficult circumstances in delivering the project.
A council report also indicated that the scheme could exceed its budget.
The latest combined programme forecast was stated to be £14.2 million higher than the May 2026 baseline.
Oxfordshire Conservatives leader Liam Walker criticised the delay and brought a birthday cake to the site on the second anniversary of its completion.
He called the project absurd and said it had become a monument to Liberal Democrats’ inability to deliver major infrastructure on schedule and within budget.
Walker also questioned whether the site should remain unused for four and a half years because it lacks an A40 connection.
Although the council had expected the park-and-ride facility to begin operating in early 2027, that timetable has moved to early summer 2028.
The remaining work is due to be completed and the site fully opened by summer 2029.
Walker said he could not place confidence in the revised opening date because of the repeated delays and cost increases.
Dan Levy, the county councillor whose ward contains the site, said the original proposal had always been over-ambitious in relation to the funding set aside for it.
He nevertheless accepted that the park-and-ride facility and its planned new junctions would be beneficial.
Levy said the scheme should have been designed to be deliverable from the outset, but added that work had begun and should now be completed.
Security and maintenance expenses have amounted to at least £9,000 per month.
Reports have recorded more than £200,000 in such costs since the site was completed in 2024.
The additional allocation for A40 improvements linked to Eynsham Park and Ride was accompanied by the postponement of planned work on Dukes Cut bridge, another element of the wider programme.
Highways repairs manager Liz Leffman said the pause did not mean that the bridge work had been abandoned.