Commentaries

Abstract

This paper surveys the technologies available for constructing a pervasive, national‐scale road pricing system. It defines the different types of road pricing, the methods by which a vehicle’s position can be determined, and then examines possible pricing regimes in the context of their technological requirements and implications. The issue of enforcement and the distribution of pricing policies are considered, and further complexities are outlined. An examination of the security aspects of such systems is made, focusing particularly on the need to ensure privacy using technological, rather than solely procedural, methods. The survey concludes that a pervasive, national‐scale deployment is unlikely to be technically achievable in the short‐term.     

Combined emergency braking and turning of articulated heavy vehicles

‘Slip control’ braking has been shown to reduce the emergency stopping distance of an experimental heavy goods vehicle by up to 19%, compared to conventional electronic/anti-lock braking systems (EBS). However, little regard has been given to the impact of slip control braking on the vehicle’s directional dynamics. This paper uses validated computer models to show that slip control could severely degrade directional performance during emergency braking. A modified slip control strategy, ‘attenuated slip demand’ (ASD) control, is proposed in order to rectify this. Results from simulations of vehicle performance are presented for combined braking and cornering manoeuvres with EBS and slip control braking with and without ASD control. The ASD controller enables slip control braking to provide directional performance comparable with conventional EBS while maintaining a substantial stopping distance advantage. The controller is easily tuned to work across a wide range of different operating conditions.     

Toward More Integrated Ocean Governance in Massachusetts: A Progress Report

The U.K. government is committed to establishing a coherent network of marine protected areas by 2012 and the recent Marine and Coastal Access Act, 2009 will designate marine conservation zones and provide wider access rights to the coast. To fulfill these goals, this article argues the need for a clearer, shared understanding of the social value of protected areas in creating new designations and managing existing ones. Although marine and coastal environments attract many people and are vitally important in terms of realized and potential social value, the majority of the public in the United Kingdom lacks understanding and awareness regarding them. Combined with this, the social value of marine and coastal protected areas (MCPAs) have been largely ignored relative to conservation and economics, with the latter invariably taking precedence in environmental policymaking. Social value reflects the complex, individual responses that people experience in a given place. Many reasons determine why one area is valued above another, and this research investigates the social value of MCPAs from a practitioner's perspective through a series of interviews. Understanding why we “socially” value MCPAs will ultimately equip managers with an informed understanding of these spaces, influence management decisions, and, potentially, policymaking. This article defines social value in the context of MCPAs in England and Wales from a practitioner perspective, explores key concepts, and suggests possible improvements in decision-making.     

Alternative information technologies for the provision of spatial information to public transport passengers in France,Germany and Spain

In France, Germany and Spain, the availability of computer‐generated itineraries to travellers in the street is still very limited, though growing slowly. Although many French towns have an effective passenger information system via Minitel, which will calculate itineraries, this is available only from the home. The vast majority of decisions about routes for journeys by urban public transport are still made using the traditional forms of spatial information abundantly displayed at bus stops and in vehicles: usually a map of the network and diagrammatic maps of individual bus or underground lines. Unfortunately a map of the whole network is often too complicated to yield the desired information easily. Alternatively the traveller may have the difficult task of comparing several diagrammatic maps of the individual lines departing from that bus stop, none of which alone can answer his spatial query: which bus lines, if any, go to my destination? The priority for the application of the computer should be the use of a geographic information system to generate automatically two types of less‐complicated map. The ‘stop‐specific route map’ shows on one piece of paper the routes of all buses from that stop, excluding of course the portions before the stop. The ‘zone map’ shows only the bus lines which serve a specific limited zone of the city, including at a reduced scale the portions extending out to their various destinations beyond the limits of the zone itself.     

Rates and mechanisms of climate change: Implications for ports and harbours

The paper explores some of the key ocean-atmosphere processes relevant to the themes of ‘global warming“ and ‘sea level rise“ addressing some of issues that form the basis of the science. It is shown that both processes as well as the data used to characterise such processes demonstrate that a) there is no such thing as a single global sea level and b) changes in extreme storminess are not uniform worldwide. Instead, trends in storminess (including Asian typoon and Atlantic hurricane activity) exhibit marked regional variability with strong regional signature linked to episodes of major El Niño and La Niña activity. Similarly, satellite data demonstrates that whereas some ocean areas have recently experienced sea level rise caused principally by thermal expansion effects, other ocean areas have been subject to cooling and sea level lowering. This account provides an introductory account that discusses the rationale for understanding the regional variability in the nature of coastal flood risk to the world’s ports and harbours.     

Using Incentives to Reduce Bycatch and Discarding: Results Under the West Coast Catch Share Program

Abstract

Catch share management was implemented in the bottom trawl sector of the West Coast Groundfish fishery in 2011 to address a range of issues including high bycatch and discard rates. The catch share program was designed to remove the incentives to discard through full catch accounting, tradeable quotas, increased flexibility in fishing, and penalties for catch overages. We assess the effectiveness of the program in meeting its environmental objectives by comparing discard weights, proportions, and variability from 2004–2010 with 2011–2016. We analyzed these metrics for species managed using quota, including historically overfished stocks, as well as for non-quota species caught in the fishery. Discard amounts decreased over time for all species and declined to historic lows after the implementation of the program, remaining low through 2016 with much less inter-annual variability. Mean annual discards of two highly-targeted quota species, sablefish and Dover sole, showed the greatest decreases, falling by 97 and 86%, respectively. The discard proportion of overfished quota species fell by 50% on average. The unanticipated decline in discards of non-quota species as well as the decreased variability in discard amounts for all species indicate that the incentives produced by catch share management provided additional ecosystem benefits.     

Sideslip estimation for articulated heavy vehicles at the limits of adhesion*

Various active safety systems proposed for articulated heavy goods vehicles (HGVs) require an accurate estimate of vehicle sideslip angle. However in contrast to passenger cars, there has been minimal published research on sideslip estimation for articulated HGVs. State-of-the-art observers, which rely on linear vehicle models, perform poorly when manoeuvring near the limits of tyre adhesion. This paper investigates three nonlinear Kalman filters (KFs) for estimating the tractor sideslip angle of a tractor–semitrailer. These are compared to the current state-of-the-art, through computer simulations and vehicle test data. An unscented KF using a 5 degrees-of-freedom single-track vehicle model with linear adaptive tyres is found to substantially outperform the state-of-the-art linear KF across a range of test manoeuvres on different surfaces, both at constant speed and during emergency braking. Robustness of the observer to parameter uncertainty is also demonstrated.