The National Infrastructure Commission has been tasked by the U.K. Government to provide expert, independent advice on pressing concerns regarding the UK’s infrastructure and to provide in-depth assessments of her national infrastructure needs up to 2050. A cornerstone of this work is the development of the National Infrastructure Assessment, which will evaluate Britain’s future infrastructure needs under a range of scenarios of future uncertainty, exploring alternative driving forces and pressures on infrastructure.

Scenarios of future infrastructure supply and demand have been developed by the NIC based on empirical evidence regarding past trends and analyses of key drivers of demand, including changes in the economy, population and demographics, climate and environment, and technology. In this manuscript we focus oncomparing estimates of demand for infrastructure services around the key sectors of energy and transport. These scenarios are tested and analysed using the National Infrastructure Systems Model (NISMOD) developed by the Infrastructure Transitions Research Consortium and departmental models including those used by the Department for Business, Energy & Industrial Strategy, and the Department for Transport.

The modelled projections provide a sobering outlook for policy planners, not only in the relentless rise in demands even under modest levels of socio-economic growth, but in the significant level of uncertainty around these estimated demands. Much of this uncertainty was provided by the scenarios of exogenous drivers that were applied but significant variance can also be attributed to differences in major model parameters, such as elasticities of demand, and in differences in model structure revealed through the comparison of results from the different models.

Arguably the most novel component of this work is this exploration of model structural uncertainty in the comparison of the NISMOD outputs with thoseof the departmental models. Such differences in model structure wererevealed most prominently in the representations of the likelihood of market-driven technological changes and in the responsiveness of demand for infrastructure services to efficiency improvements. These differences were further accentuated through the cumulative effect of interdependencies between sectors, as was the case for the electrification of transport.