The legacy of the Covid-19 pandemic continues to pose challenges for cities up and down the country.
Changing patterns of work - including the growth of home and hybrid working - have challenged assumptions about what their future transport needs might be.
For example, the chart below from our new report shows that number of people in workplaces in the seven largest cities outside London is lower than before the pandemic, on every day of the week
Then again, there’s evidence that heavy congestion is beginning to return to roads since the pandemic, and that is especially true in city centres.
Traffic jams are frustrating for drivers, bad for air quality, and a likely barrier to growing regional economies and levelling up.
Bustling, vibrant cities drive successful regional economies, attracting jobs, investment and opportunities for leisure.
We think that facilitating more journeys into and around cities is a social and economic necessity.
Cities will need to use both 'push' and 'pull' to get people out of cars
Making public transport and active travel more accessible, reliable and safe will likely only get us so far
Local leaders are best placed to identify the improvements that will work best for their cities. Government needs to give them the tools and resources, including long term stable funding cycles, to support their plans.
Brand new infrastructure will not always be the right solution: making better use of existing assets by using technology and data can help make networks more accessible and efficient.
In some places, substantial investment in new forms of mass transit may be necessary.
Dealing with uncertainty
Following the Covid pandemic, the shape of future demand for public transport is impossible to predict with confidence. Projects need to be adaptable to a range of different future scenarios.
This can be achieved by taking a modular approach, beginning with a core of 'low regrets' investments before moving on to more ambitious phases, or by designing solutions that can easily be flexed at a later stage.
Making the shift
'Demand management' - such as schemes to reallocate road space or charge drivers for access at certain times - also has a likely role in supporting the shift.
The aim of such schemes should not be to put people off making journeys altogether, but to encourage people to opt for more space-efficient modes of travel in congested cities. However, planners must be careful not to disadvantage certain groups.
A sustainable approach to facilitating more trips into city centres
Increasing urban travel has to be done in a way
that helps us reach net zero
Towards net zero transport
It is going to be particularly tough for the transport sector to meet its targets for carbon emissions, set in the government's sixth carbon budget, which should be achieved by 2035
By 2050, the UK's vehicle fleet should be largely powered by electric vehicles.
Active options for city centre travel
But while there's good progress on the electric vehicle switchover, we'll need to do more to cut emissions from transport by the level required, in little more than ten years.
A focus on encouraging a shift from people making trips in private cars, to people using public transport of active travel - that is, options like walking or cycling - will therefore also help cities achieve emissions targets.
"More trips with fewer negative impacts would be challenging to deliver in normal times, but it's doubly so with the fog of uncertainty generated by the pandemic. Cities have to remain ambitious in their visions for the future, but base that ambition on plans which are flexible enough to cope with whatever the future holds."
Sir John Armitt, Chair, National Infrastructure Commission
Future urban transport
The challenge of preparing our urban transport networks for the longer term is not an easy one.
But, working together, local leaders and central government can ensure city regions are acting now to support thriving places - where journeys can connect people to each other, and places of work and leisure, within carbon constraints.
For our part, the Commission will be undertaking more detailed work on future scenarios ahead of making recommendations on long term investment in urban and interurban transport, as part of the next National Infrastructure Assessment.
Find out more about our ideas on urban transport by reading our new Getting cities moving report.