Jari Kauppila

Managing Highways for Better Reliability: Assessing Reliability Benefits of Ramp Metering

Despite the importance of reliability, few countries monitor it or explicitly incorporate it into transport policy making. Nevertheless, a number of policy options are available to improve this aspect of transport management. Active management of the network through ramp metering is recognized as an efficient way to control motorway traffic and improve average travel time. Far less is said about the reliability benefits of ramp metering. This paper assesses reliability benefits of ramp metering on the basis of a before-and-after study on the A6W, a French motorway near Paris. Several indicators for travel time variability are applied before and after the introduction of ramp metering. For purposes of taking reliability into account in policy impact evaluation, cost–benefit assessment provides a consistent framework within which to assess the monetized benefits. The monetary value of the reliability benefits of ramp metering is therefore calculated, and the policy implications of the results are discussed. The results suggest that in addition to providing gains in average travel time, ramp metering significantly improves reliability of travel times. It is also proposed that indices such as buffer time or planning time are useful for communicating the results, both for network operators and for users. Failing to unbundle the time-savings benefits of a project between average travel time and the variability in travel time is likely to lead to suboptimal policy solutions. Managing existing capacity better can be a cost-effective way to improve both average travel time and the variability in travel time.

Global Urban Passenger Travel Demand and CO2 Emissions to 2050

This paper presents long-term scenarios on the development of urban passenger mobility and related carbon dioxide (CO2) emissions by 2050 in global cities that have populations greater than 300,000 on the basis of the International Transport Forum’s new global urban passenger transport model. Results from the policy scenarios analysis show that in the baseline scenario total motorized mobility and related CO2 emissions in cities will grow by 94% and 27% in 2050 compared with 2015. The share of private cars will continue to increase in developing regions while slightly decreasing in developed economies. Policy measures exist to fulfill mobility demand while reducing the carbon intensity of travel. Technology contributes the most to the CO2 mitigation in the most transit-oriented scenarios. Behavioral policies such as fuel tax, lower transit fares, and controlled urban sprawl can bring the additional mitigation efforts required to make cities sustainable and are essential to combat congestion and health issues.