Smart Use of Roads – a new report

Congestion is most successfully addressed by a complete set of tools for managing traffic demand and integrating transport and land-use planning

This article is the executive summary of the International Transport Forum’s (ITF) ‘Smart Use of Roads’ research report published in March 2019, which examines strategies and technologies applied to better utilise existing road networks.

It has long been recognised that capacity expansion through the construction of new roads alone is not an efficient approach to meeting peak demand, especially in cities with a well-developed road network. This approach to congestion is often unsustainable because pent-up demand quickly fills up new road space and congestion will return.

The report summarises the findings of a workshop on alternative responses to congestion organised by the ITF’s working group on the smart use of roads. The workshop – held in Tokyo in October 2018 – brought together 39 experts and practitioners from 11 countries.

Participants discussed the use of real-time data to identify congestion bottlenecks and to provide dynamic route guidance to travellers, and reviewed localised infrastructure measures to relieve congestion in the short to medium term. The workshop also examined the way in which road tolls have been modified to relieve congestion on the expressway networks of Tokyo and Chinese Taipei and the evolution of Singapore’s road pricing system to maintain its effectiveness in managing demand.

What we found

Making smarter use of roads is increasingly the focus of investment in trunk road networks and their management. This involves investment in information and communications technology, and the use of a mixture of localised and network measures, to optimise use of the network and maximise flow on existing roads, rather than simply adding capacity.

The strategy is a response to the unsustainable costs of unlimited expansion and the difficulties of expansion in densely built-up areas. More fundamentally, it responds to the failure of strategies based on expansion of capacity to manage congestion in cities with a well-developed network, with expansion generating additional demand and driving mobility to be more and more car-dependent.

There are three broad categories of real-time traffic information:

  1. Those collected from intelligent transport systems (ITS) such as systems with roadside sensors, electronic toll collection (ETC) systems and mobile communications networks.
  2. Data from ETC systems, combined with traffic counts, can be a useful substitute for ITS data, particularly when the onboard units (OBUs) record probe data on driving behaviour (such as braking and acceleration) and trip patterns (origin, destination, parked time). Combined, this can provide information on trip purpose.
  3. Mobile phone network data can provide similar if less complete data to that obtained from ITS systems, but with a wider geographical coverage, and can contribute to assessment of traffic volumes to make projections of network performance.

Past experience shows that investment in ITS smart motorway technologies can achieve better value for money than network expansion. But such investment can be costly and therefore ITS infrastructure is likely to be installed mainly on selected strategic corridors. Mobile network data can be a valuable supplement to ITS and ETC data, but its use is still at an early stage and business-to-government data sharing is not common.

A number of investments that cost less than adding lanes to motorways can relieve congestion, with much higher benefit-cost ratios (BCRs) than network expansion. These include adapting hard shoulders (safety lanes) to take peak-hour traffic, controlling access to expressways through ramp metering and variable speed limits, and speed-calming devices to smooth and increase traffic flow. The latter include pulsing banks of LED strips providing a visual signal that acts to synchronise and adjust vehicle speeds.

The safety implications of hard-shoulder running are addressed by lowering variable speed limits when in use and variable message sign (VMS) posting to evacuate lanes in case of emergency. In practice, hard-shoulder running is found to reduce both safety risk and travel time and improve journey time reliability.

Tolls on tolled roads can be adjusted to steer traffic away from congested sections of the network. This has been done very successfully in Tokyo, following completion of its trunk ring roads. What were largely distance-based tolls were modified in 2016 to equalise charges for crossing the city through the centre or via the ring roads. This resulted in a large shift of traffic to the ring roads, cutting congestion sharply.

Tolls on the national expressway network in Chinese Taipei have been rationalised and modified to begin to steer demand away from congested locations and periods. The biggest reduction in congestion with the modification of Chinese Taipei’s motorway tolls has been achieved by removing toll plazas. Manual fee collection has been replaced entirely with drive- through ETC technology after a phase-in period to allow for reassignment of labour. Other tolled motorway systems should replicate this experience.

Congestion is most successfully addressed by a complete set of tools for managing traffic demand and integrating transport and land-use planning. Singapore has developed the most comprehensive policies. These include joint planning of transport – infrastructure investment and public transport services – with land-use change and property development, together with a full suite of measures to manage car ownership and use. The tools include auctioning of permits to buy cars that limits car ownership, as well as charges on the use of cars – fuel taxes, parking charges and road pricing.

Tokyo uses a similarly broad set of demand-management instruments to cut congestion to current low levels. For example, car ownership is limited by the requirement to own or lease off-street parking space before purchase, and urban expressways are tolled, with congestion-based tolling being considered for the future. At the same time, the expressway network is being expanded, including development of ring routes around urban areas, to complete Tokyo’s basic road network.

What we recommend

A range of effective, active traffic demand-management measures, such as hard-shoulder running, have been used in many places with proven results

Make use of smart technologies part of the response to congestion

ITS use information and communication technologies to enable users to be better informed and make more coordinated and smarter use of transport networks. Investment in ITS provides better value for money than network capacity expansion in some circumstances, and should be considered as part of strategies to address congestion.

For cities with existing tolling systems, upgrading tolling technologies can reduce congestion at charging points by eliminating the need for motorists to stop for payment. Modifying existing tolling systems to manage congestion at specific locations and time of day is a particularly cost-effective option.

Invest in improving junctions where these create bottlenecks

In general, one of the major causes of congestion on motorways is reduced traffic flow around interchanges and ramps where lanes merge and diverge. Experience in Tokyo demonstrates that localised investment to improve road geometry and expand capacity at these points can be very successful in eliminating congestion on the network, at least where overall traffic demand is constrained by tolls.

Use hard-shoulder running and ramp metering to get the most out of trunk road capacity

A range of effective, active traffic demand-management measures, such as hard-shoulder running, ramp metering and speed harmonisation, have been used in many places with proven results. These measures provide better value for money than network expansion, at least in the medium term.

Use congestion pricing for active traffic management as part of integrated urban policies

Charging for the use of roads with prices differentiated by route, location, time of day and day of the week has proven to be effective in changing behaviour and limiting congestion, notably in Singapore. Demand-responsive road pricing is the most efficient way of balancing supply and demand for road use in the long term.

In cities, it works best as part of a comprehensive set of measures to manage car ownership and use and integrate land-use and transport planning. Without road pricing and/or instruments that price the impact of consuming road and parking space into the cost of owning a car, it is congestion itself that regulates demand.

Adopt barrier-free electronic tolling to remove bottlenecks

Even simple forms of congestion pricing, without time and distance-based differentiated pricing, can be effective in managing demand, as London’s congestion charge demonstrates. A range of technologies can be used for barrier-free toll collection and enforcement, and experience in Chinese Taipei and Singapore shows how simple systems can evolve over time to incorporate technological innovation for more effective traffic management. Replacing manual fee collection with barrier-free systems should be a priority for removing congestion bottlenecks.

Whatever system is selected, the focus should first and foremost be on ensuring the basic toll collection and enforcement function is operational before incorporating other functions.

The International Transport Forum is an intergovernmental organisation with 59 member countries (including New Zealand). It acts as a think tank for transport policy and organises the annual summit of transport ministers. ITF is the only global body that covers all transport modes. The ITF is politically autonomous and administratively integrated with the OECD.

The full report can be downloaded at