Evidence-based improvements in delivery models

This framework showcases proven improvements to the infrastructure delivery process made by G20 governments and industry, categorised by six common themes. Select a theme to view challenges, suggested improvements, related case studies, and resources.

View challenges and improvements by theme

Imbalanced risk allocation between client and contractor due to a lack of investigative works or consultation in the planning process.

For linear / urban / transport infrastructure (involving tunnelling civil works and utilities relocation) the lack of reliable information around certain risks precludes its optimal allocation (e.g. willingness to have risk transferred from client to contractor).

Imbalanced risk allocation results in insufficient contractor appetite to deliver large complex projects or substantial risk premiums being priced into tenders. To attract adequate competition risk must be well defined and quantified.

Clients may apply their risk experience from smaller scale social infrastructure projects to large scale civil projects, or alternatively use precedents from prior projects with different characteristics inappropriately in the allocation of risk.

What improvements have been used to address the challenges? Improvement How have infrastructure projects benefited from improvement? Benefit

Use early works to de-risk pre-construction covering utility relocations, land acquisition and other investigation works conducted by either the project owner or its contractor to de-risk the project as much as possible.

Case Studies:


Carefully consider seeking to transfer risks to contractors when the ‘unknown’ factor is too high or ‘non-priceable’ (e.g. in relation to linear / civil works and especially for large infrastructure, utilities, ground conditions, contamination.

Using a model with a collaborative approach to deal with such risk may present the best option and allow the client and contractor to have equitable risk sharing mechanisms. This ensures all parties are commercially aligned to mitigate such risks and enables realistic pricing from contractors with less risk premium.

Case Studies:

  • Happy Valley Underwater Storage Scheme (Hong Kong SAR, China) project developed an underground stormwater storage tank to alleviate flooding in a low-lying part of the island. The project used a NEC3 ECC target cost contract (activity schedule) due to the project’s complexity. The contract used early warning notices as soon as either the client or contractor became aware of any major issues and held meetings to discuss these within 24 hours to ensure they were mitigated, resulting in the project being completed a year ahead of time and under budget.

  • Port of Miami Tunnel (USA) created a contingency fund to pool risk in the event of unforeseen costs, and shared the O&M risk premium between the public and private sectors. This was important as the project was constructed under a busy shipping channel in an environmentally sensitive area, and insurance or potential unforeseen costs were both high (case study from GI Hub PPP Contract Management Tool). 


  • Cost-based procurement approach (Hong Kong SAR, China) has been promoted by the Hong Kong Government for its public works projects. This approach includes the use of NEC ‘Open Book’ target cost models to avoid paying a risk premium unnecessarily through a traditional design and build contract. By adopting the NEC contract form, the risks are more equitably shared, and the government will only pay for the risks materialised.
  • NEC 4 Open Book Target Cost approach provides the mechanism to work collaboratively between contractor and client, sharing the benefits of cost savings as well as the risks of cost overruns. Using a target cost with an incentivised mechanism termed a painshare or gainshare regime, contractors can find innovations to improve outcomes or mitigate risks, with the client equally incentivised to do all it can to deliver an optimal outcome.

Use collaborative contracting and target price contracts (e.g. Alliance style model) where the owner is willing to collaborate for a best for project outcome, as opposed to fixed-priced contracts, as a way to attract contractors that may otherwise pass on projects where the scope is insufficiently defined due to the risk it represents.

Case Studies:

  • Heathrow T5 (UK) was the largest construction project in Europe at the time, involving the building of a new airport terminal. It used an innovative approach with the client holding all the risk for the project, with an integrated team that was co-located delivering to target cost contracts on an open book basis. This approach demonstrated how a large complex project can be delivered using a collaborative method with good risk mitigation practices by contractors, aligned with a commercial incentive to perform.

Case Studies
Heathrow T5 (UK)

Use market sounding to explore the key risk items that need addressing to structure the project such as packaging and risk allocation, to meet the expectations of bidders in the market.

Case Studies:

  • New Dunedin Hospital (New Zealand) is a new 411 bed hospital to be constructed in the lower South Island of New Zealand and set to be the largest hospital in the country. A market engagement process was undertaken to provide information on the project and to inform the market’s view on aspects such as packaging and risk allocation. This informed the final packaging released to the market.

Use a risk allocation approach that considers the project characteristics and test this with the market or through an interactive tendering process.


  • Infrastructure NSW Interactive Tendering Guidelines Draft (Australia) develops a set of best practice interactive tendering guidelines for government and industry. Its objectives are to improve proposals from the private sector, minimise misunderstanding between the tenderer and the procuring authority as well as ensuring a collaborative exchange of information to maximise the value of the proposals received. It reduces the probability of avoidable risks being priced into proposals by tenderers through this information exchange.
  • GI Hub PPP Risk Allocation Tool provides a reference guide for government on the appropriate allocation of project risks for a variety of project types. The tool helps ensure that risks in PPP contracts are allocated in a way that achieves value for money and are viable for the private sector.