Strategic Planning

Garbage In, Motorway Out: Why Congestion Evaluation Keeps Failing Us

There is a lot of criticism of the way we have historically measured traffic congestion costs and evaluated congestion-reduction strategies. This report from the Victoria Transport Policy Institute (VTPI) in Canada looked at both.

Key Takeaways

• A strategy to reduce congestion may seem effective and beneficial when evaluated one way, but wasteful and harmful when evaluated another way.
• Planning decisions involve trade-offs between congestion reduction and other goals such as affordability, safety and independent mobility for non-drivers.
• Overvaluing congestion costs and roadway expansion benefits leads transportation agencies to overinvest in urban highway projects and underinvest in multimodal planning, vehicle travel-reduction strategies, and more integrated planning.
• Current congestion evaluation practices are inadequate:

Congestion reduction strategies:

• Traffic was previously modelled as a fluid that flows through a road system, but we now recognise that it often behaves like a gas that fills available space and can be condensed with suitable incentives.
• Congestion tends to self-limit; it increases until delays prevent more peak-period vehicle trips. As a result, congestion seldom becomes as severe as predicted by extrapolating past trends.
• Current congestion evaluation undervalues:
  • Non-auto mode improvements by ignoring the congestion avoided by non-auto travel
  • The parking cost savings that result when commuters drive less,
  • Vehicle ownership savings that result if households need fewer vehicles.
  • Health and enjoyment benefits from more active travel,
  • Improved accessibility for non-drivers and reduced chauffeuring burdens for drivers from better non-auto travel options,
  • The fairness provided by better travel conditions for non-drivers.
• Roadways should not be expanded until all low-cost, high-benefit congestion reduction solutions have been fully implemented:

Comment

The VTPI does an excellent job of tearing apart the common practice used to justify road expansion projects. It is an important pillar of road-building advocates.

Nevertheless, it is necessary but not sufficient.

To significantly reduce the number of road expansion projects, we need to undermine the source - public support.

What Next?

How good is your evaluation of congestion-reduction strategies?

Strategic Planning

Car Dependency in the Suburbs: Lessons from Europe's Best Cities

Removing the car dependency of the suburbs remains one of the biggest challenges in transport. The author of this report toured Europe in search of solutions he could bring back to the UK.

Key Takeaways

• Some of the most promising alternatives to single-occupancy car use are the most neglected by policymakers. This includes carpooling and car clubs, and new forms of ‘light mobility’ like E-Bikes.
• The challenge of form: The transport sector likes to have one approach for everywhere; however, a one-size transport policy will not fit all suburbs, which vary widely in density and form.
• The challenge of scale: There are two challenges related to scale:
  • The daunting size of the task, given that many suburbs are dilapidated and alternatives to single occupancy car use are limited and fragmented, and
  • The fact that pilot initiatives with the most potential in lower density suburbia must be of sufficient size to give a meaningful indication of what would happen if scaled up.
• The challenge of implementation: With a lower population density than urban centres, and therefore less public transport provision, suburbs need a wider mix of travel options. However, national and sub-national governments do not see some suburban travel options with the most potential (such as e-bikes) as a policy or funding priority.

Lessons from ‘next-level’ cities:

• Pursue the good urban life: What next-level cities do is driven by what this paper terms the ‘civic imperative’, seeking to answer the question: ‘what is the good urban life?’
• Combine idealism with objective analysis: Next-level cities look objectively at what they inherit and where they want to go next. When they try something new, they pilot it at a meaningful scale.
• Work across professional divides: Individual initiatives are seen as contributing to this broad goal, and it’s the place-makers who are in charge rather than the engineers.
• Learn by doing: Forward-thinking cities are in a virtuous circle of trying, doing, learning and failing better

Advice to government:

• Shift the policy focus on car electrification to tackling residential charging challenges.
• Establish a dedicated ‘future suburbs’ funding stream for piloting innovative approaches at a meaningful scale
• Co-ordinate action on planning processes, engineering standards and co-procurement to cut the cost and speed up implementation of new light rail schemes.
• Shift the balance of national funding from building new highways to greening and reducing flood risk.
• Support the re-greening of the UK's front gardens.

Comment

As the report says, the challenge for transport planners is that there is no one-size-fits-all solution to suburbs; they are just too varied, even within a single country.

The challenge is that the capability and mindset to try, do, learn and fail better is very rare and difficult to create. You cannot simply declare you are going to make the change; you need to reengineer decision-making in our transport agencies.

The latest Freewheeling podcast has an interview with the author.

What Next?

Can you create a culture that allows a virtuous circle of trying, doing, learning and failing better to improve transport in suburbs?

Strategic Planning

Systematically Wrong: How Road Traffic Forecasting Failed the Public Purse

This week seems to be an induced demand week. This paper, by Professor Phil Goodwin, examines the impact of induced demand on benefits in the UK context, on behalf of the UK Department for Transport.

Key Takeaways

• For a period, extra capacity will reduce costs, in time and money, which will itself trigger more traffic growth, called ‘induced traffic’.
• The process also applies in reverse: when road capacity is reduced or reallocated to public transport, active travel, or other functions, demand declines.
• In the appraisal of the expansion of highway capacity, induced traffic can cause additional costs, particularly congestion, environmental, social, and other costs.
• In other circumstances there can be induced demand without imposing such additional costs, indeed sometimes bringing extra economic, health, environmental, and other benefits.
• If no account is taken of induced traffic effects, the tendency will be to overestimate how bad the conditions will be without the project and to overestimate how good they will be with the project, thereby exaggerating the benefit.
• Long-established freight modelling practice still assumes fixed demand, with no induced traffic, for LGVs or HGVs. This is not supported by the substantial body of evidence now available.
• The accuracy of the do-minimum conditions is as important as the do-something conditions and, in particular, will require the calculation of any damping effect on demand in response to rising congestion.
• If transport prices do not reflect marginal social costs (which is usually the case), there will be biases in the estimation of effects of increased capacity and other interventions.
• Even the best available models do not consider a complete set of behavioural responses and are uninformative about how long it takes for the dynamic effects to emerge.
• Over the entire period from the 1989 and subsequent official National Road Traffic Forecasts through 2025, national traffic growth has been systematically overestimated.
• From about 2002 until 2024, ex post evaluation of induced traffic from completed highway projects was carried out by National Highways in its POPE programme, using flawed methods that focused on the difference between the original forecasts and the observed outcomes; these tended to underestimate induced traffic and overestimate traffic benefits.
• There are also emerging developments in modelling which may be more effective in identifying specific aspects of induced demand.

Comment

This paper adds to the weight of evidence that the UK government has been overinvesting in road expansion. Worryingly, many other countries have adopted or based their appraisal processes on the UK's, exacerbating the problem internationally.

Even though the best available models are limited, many schemes still struggle to achieve a benefit-cost ratio (BCR) over 1 and compare unfavourably with public and active transport projects that have much higher BCRs. Better prioritisation of projects with the highest BCRs would be a major step in the right direction.

What Next?

Are you prioritising projects with the highest BCRs?

Quick Adventures in Transport Wonderland

Here is what else I came across this week:

• ​Operationalising the ‘Movement and Place’ framework: from functional to configurational street types in urban design and planning practice - A research paper that suggests enhancements to the Movement and Place framework.
• ​Strategies and sustainability in motion: An analysis of mobility and climate change policies in Greater London - A research paper that looks at the challenges of implementing climate change strategies in mobility.
• ​Reimagining assurance: reflections from the PMI Global Executive Council - A blog suggesting improvements to position project assurance as enabling delivery.

Podcast

Light Rail

In this week's Transport Leaders podcast, we discussed light rail, including why Dublin, Edinburgh and Sydney all made the same mistakes.

👂 Listen here.

👀 Watch here.

Tool

THE TRANSIT PRIORITY ATLAS

The Transit Priority Atlas maps, illustrates, and makes broadly accessible the strategies and tools cities worldwide have implemented to ensure faster and more reliable street-running transit.