Eleven major capital projects in NI have not been completed on time and have run millions over budget, according to an Audit Office report.
Seven of the 11 were identified by the executive in 2015 as flagship projects.
The report highlights funding, planning and legal issues, and a lack of construction industry interest.
Key findings from the report include:
- The A5 upgrade, linking counties Londonderry and Tyrone, has a £300m overspend and has been overrun by 10 years.
- The Regional Children's Hospital has a £130m overspend and has overrun by five years.
- The cost of building UU's new Belfast campus is now expected to be £363.9m - more than £100m over budget. The European Investment Bank (EIB) has already withdrawn a £150m loan because of project delays.
- The new Gaelic Athletic Association (GAA) stadium at Casement Park in west Belfast has an overspend of £33m. It has still not started three years after the expected completion date.
- The critical care centre at the Royal Victoria Hospital is over budget by £57m and has over run by eight years.
- The new maternity hospital in Belfast is six years overdue and is £17m over budget.
A spokeswoman for UU said the new campus would "deliver a progressive student experience in a state-of-the art city centre campus".
She added: "An independent assessment of this project's overall regeneration impact details benefits to the NI economy of £1.4bn, through this significant investment in the aspirations of our young people, the city and beyond."
The Audit Office report also says the Strule Shared education campus in County Tyrone will be further delayed until at least 2024 and has also gone about £45m over budget.
The biggest school building project in Northern Ireland will eventually see six schools built on the site of the former Lisanelly army base in Omagh.
Although work began on the Strule campus in 2013, only one school is currently open despite the original target date of 2020 for the entire project.
A spokeswoman for the Department of Education (DE) said it remained fully committed to delivering the programme.
She added: "The next phase of construction for Strule Shared Education Campus has been delayed as a result of tendering issues in appointing a contractor.
"In light of this delay the campus go live date has been revised, and the Department is provisionally working towards September 2024."
The 11 projects identified by the Audit Office:
•Mother and Children's Hospital - regional children's hospital and maternity hospital.
•Belfast Transport Hub.
•Belfast Rapid Transit.
•Regional and Sub-Regional Stadia (Casement).
•Desertcreat College ( A joint training college for Northern Ireland's police, fire and prison services).
The additional four projects:
•Critical Care Centre at the Royal Victoria Hospital;
•Primary Community Care Centres at Lisburn and Newry;
•Ulster University - Greater Belfast Development;
•Strule Shared Education Campus.
Kieran Donnelly, auditor general, said major capital projects are complex and delivery problems are not unique to Northern Ireland.
"Existing, cumbersome governance and delivery structures within the Northern Ireland public sector can be a barrier to achieving value for money," he added.
This is not the first report that has raised questions around how capital projects are delivered in Northern Ireland.
In 2013, a review of commissioning and delivering major infrastructure projects found that "the system as a whole is not fit for purpose".
The report did not receive universal support. Proposed reform stalled and consequently some of the improvements were not realised.
The Audit Office echoes previous reports that highlighted the need to eliminate duplication, improve project prioritisation, reduce bureaucracy, and drive better deals by increasing innovation.
Capital projects are identified in the Investment Strategy, a rolling 10-year plan prepared by the Strategic Investment Board on behalf of the executive.
The original strategy ran from 2005-2015, and was updated for the period 2011-21.
A further update has been put on hold following the collapse of devolution in Northern Ireland.