The protocols of bidding for infrastructure projects need reform so the preferred provider can negotiate debt and equity funding with a diverse range of investors, a senior executive of National Australia Bank proposed last night.Rick Sawers, head of wholesale banking at NAB, used his speech to an industry dinner to lay out a menu of options for the funding of infrastructure."Without appropriate funding mechanisms for our economy, our living standards are at risk," Sawers said."We must seize the opportunity [of growing pools of investment funds]... to look at funding arrangements."Ratings agencies, regulators and commentators have all expressed concern at our current funding models."Sawers estimated that "a further A$700 billion in essential infrastructure is needed", and said there was unlikely to be sufficient finance to meet the demand.He called for "a more symbiotic relationship between the banking and the superannuation sectors", with the latter channelling more investment into debt securities.Citing precedents in the UK and Canada, where a pipeline of smaller, more defined infrastructure deals is normal, Sawers called for "projects that come in smaller parcels [and that are] less complex and more appealing to super funds.""Currents bids for PPPS [public-private partnerships] must be fully funded before they are awarded."I ask why not run the funding processes once the [preferred] bidder is known?"He said there "would be more time to arrange or structure the funding to suit the investors."Sawers also called for a re-think on the liquidity policies of super funds, and also of APRA's standards."The current focus on liquidity [in super funds] creates a mindset where you can get your cash back immediately, or close to immediately.Sawers also added NAB's backing to calls for a "financial securities backstop scheme", an idea pushed by CBUS chair Steve Bracks and also by superannuation industry reviewer Jeremy Cooper.Sawers was speaking at the Melbourne Financial Services Symposium.