Road maintenance planning using network flow modelling

This paper presents a road maintenance planning model that can be used to balance out maintenance cost and road user cost, since performing road maintenance at night can be convenient for road users but costly for highway agency. Based on the platform of the network traffic flow modelling, the traffic through the worksite and its adjacent road links is evaluated. Thus, maintenance arrangements at a worksite can be optimized considering the overall network performance. In addition, genetic algorithms are used for maintenance planning in order to find the best maintenance arrangements for the worksites. The key variables in the optimization model involve the starting time of maintenance works during the day, their duration, the duration of the break during the maintenance work and traffic signal controls at the worksite

The UK Transport Carbon Model : An integrated life cycle approach to explore low carbon futures

Peer reviewedPostprin

Variation in abundances of common bird species associated with roads

1. The global road network, currently over 45 million lane-km in length, is expected to reach 70 million lane-km by 2050, while the number of vehicles utilising it is expected to double. Roads have been shown to affect a range of wildlife, including birds, but most studies have been relatively small scale. 2. We use data from across Great Britain to analyse the relationships between roads and the spatial distributions of bird populations. We model counts of 51 common and widespread species from the U.K. Breeding Bird Survey in relation to road exposure, which we calculated for each count site using the density, distance and traffic volume of all roads within a 5 km radius. In these models, we incorporate other factors known to affect bird populations, including agricultural intensity, human population, habitat and climate. Importantly, we also account for differences in detectability of birds near to roads. 3. The abundances of 30 species were strongly significantly related to exposure to either major or minor roads. Species were generally in higher abundances with increasing exposure to minor roads (20/28). In contrast, most significant associations between major road exposure and bird abundance were negative (7/8). 4. For species with significant effects of road exposure, we assessed how estimated abundance changed across the central 50% of road exposure experienced for each species. The mean decrease in abundance was 19% and the mean increase was 47%. These changes in bird abundance were up to half as large as those associated with increasing agricultural intensity, a factor often cited as a major cause of bird population changes. 5. Synthesis and applications. Our research shows many species to vary in abundance with increasing road exposure. This suggests that roads may modify bird populations on a national scale and that their potential as drivers of biodiversity change should not be overlooked. Our work highlights the need for appropriate mitigation of roads, particularly in areas important for avian biodiversity. This could include efforts to reduce impacts of road noise and/or collisions, such as reduced speed limits or quieter road surfaces in sensitive areas

Commuting and wellbeing: A critical overview of the literature with implications for policy and future research

© 2019, © 2019 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group. This review provides a critical overview of what has been learnt about commuting’s impact on subjective wellbeing (SWB). It is structured around a conceptual model which assumes commuting can affect SWB over three time horizons: (i) during the journey; (ii) immediately after the journey; and (iii) over the longer term. Our assessment of the evidence shows that mood is lower during the commute than other daily activities and stress can be induced by congestion, crowding and unpredictability. People who walk or cycle to work are generally more satisfied with their commute than those who travel by car and especially those who use public transport. Satisfaction decreases with duration of commute, regardless of mode used, and increases when travelling with company. After the journey, evidence shows that the commute experience “spills over” into how people feel and perform at work and home. However, a consistent link between commuting and life satisfaction overall has not been established. The evidence suggests that commuters are generally successful in trading off the drawbacks of longer and more arduous commute journeys against the benefits they bring in relation to overall life satisfaction, but further research is required to understand the decision making involved. The evidence review points to six areas that warrant policy action and research: (i) enhancing the commute experience; (ii) increasing commute satisfaction; (iii) reducing the impacts of long duration commutes; (iv) meeting commuter preferences; (v) recognising flexibility and constraints in commuting routines and (vi) accounting for SWB impacts of commuting in policy making and appraisal

Evaluating the long-term impacts of bus-based park and ride

Many park and ride (P&R) schemes worldwide are based on rail transport, however there has also been substantial development of bus-based P&R in which an enhanced bus service operates between a P&R site and an urban centre. This has been particularly marked in Britain, often in historic cities (such as York, Oxford and Cambridge). Development of busways has also provided opportunities for complementary P&R development. Nonetheless, a net increase in passenger car unit (pcu)-kilometres may be observed, despite a reduction on the principal radial corridor. This is due to increased car-kilometres in catchment areas of P&R sites, but this simple additive approach to changes in pcu-km may not reflect overall impacts if pcu-km are removed from a congested urban corridor. By using monetised external cost per pcu-km for different road types and traffic conditions (such as those in ‘WebTAG’ guidance in Britain), the net effect can be expressed in economic terms. Presented here is a case study of the Chelmsford system, showing that a net economic benefit may be attained, even though a net increase in pcu-km has occurred. Energy savings through diversion of car occupant trips to the Cambridgeshire busway are also assessed

Peak car and increasing rebound: a closer look at car travel trends in Great Britain

This paper uses econometric analysis of aggregate time-series data to explore how different factors have influenced the demand for car travel in Great Britain since 1970 and how the rebound effect has changed over that time. Our results suggest that changes in income, the fuel cost of driving and the level of urbanisation largely explain travel trends over this period – with recent reductions in car travel (peak car) being driven by a combination of the rising fuel cost of driving, increased urbanisation and the economic difficulties created by the 2008 financial crisis. We find some evidence that the proportion of licensed drivers has influenced aggregate travel trends, but no evidence that growing income inequality and the diffusion of ICT technology have played a role. Our results also suggest that the rebound effect from improved fuel efficiency has averaged 26% over this period and that the magnitude of this effect has increased over time. However, methodological and data limitations constrain the level of confidence that we can have in these results

A methodology for measuring the sustainability of car transport systems

Measuring the sustainability of car fleets, an important task in developing transport policy, can be accomplished with an appropriate set of indicators. We applied the Process Analysis Method of sustainability assessment to generate an indicator set in a systematic and transparent way, that is consistent with a declared definition of a sustainable transport system. Our method identifies stakeholder groups, the full range of impacts across the environmental, economic and human/social domains of sustainability, and those who generate and receive those impacts. Car users are shown by the analysis to have dual roles, both as individual makers of decisions and as beneficiaries/sufferers of the impacts resulting from communal choice. Thus car users, through their experience of service quality, are a potential force for system change. Our method addresses many of the well-known flaws in measuring transport sustainability. The indicator set created is independent of national characteristics and will be useful to transport policy practitioners and sustainable mobility researchers globally. © 2013 Elsevier Ltd

Updating Outdated Predictive Accident Models

Reliable predictive accident models (PAMs) (also referred to as safety performance functions (SPFs)) are essential to design and maintain safe road networks however, ongoing changes in road and vehicle design coupled with road safety initiatives, mean that these models can quickly become dated. Unfortunately, because the fitting of sophisticated PAMs including a wide range of explanatory variables is not a trivial task, available models tend to be based on data collected many years ago and seem unlikely to give reliable estimates of current accidents. Large, expensive studies to produce new models are likely to be, at best, only a temporary solution. This paper thus seeks to develop a practical and efficient methodology to allow currently available PAMs to be updated to give unbiased estimates of accident frequencies at any point in time. Two principal issues are examined: the extent to which the temporal transferability of predictive accident models varies with model complexity; and the practicality and efficiency of two alternative updating strategies. The models used to illustrate these issues are the suites of models developed for rural dual and single carriageway roads in the UK. These are widely used in several software packages in spite of being based on data collected during the 1980s and early 1990s. It was found that increased model complexity by no means ensures better temporal transferability and that calibration of the models using a scale factor can be a practical alternative to fitting new models

Rebound effects in UK road freight transport

This paper analyses aggregate time-series data to estimate the direct rebound effect in UK road freight over the period 1970–2014. We investigate 25 different model specifications, conduct a comprehensive set of diagnostic tests to evaluate the robustness of these specifications and estimate the rebound effect using three different elasticities. Using the mean of the statistically significant estimates from these specifications, we estimate a direct rebound effect of 61% - which is larger than previous estimates in the literature and almost twice as large as the consensus estimate of direct rebound effects in road passenger transport. Using the mean of the estimates from our most robust models, we estimate a slightly lower direct rebound effect of 49%. Our estimates are fairly consistent between different model specifications and different metrics, although individual estimates range from 21% to 137%. We also find that an increasing proportion of UK road freight is being undertaken by foreign registered vehicles, and that increases in the vehicle weight limits have encouraged more freight activity. We highlight the significant limitations imposed by the use of aggregate time series data and recommend that further studies in this area employ data from vehicle use surveys

Motor traffic on urban minor and major roads: impacts on pedestrian and cyclist injuries

This article compares per-mile risks posed by motor traffic to pedestrians and cyclists on urban major and minor roads. Carrying out new analysis of police injury data from 2005-15, the paper finds that per billion vehicle miles, motor vehicles on minor roads create more pedestrian casualties than motor vehicles on major roads. Specifically, for KSI (killed or seriously injured) injuries the rate per billion motor vehicle miles is 17% higher on minor roads (47 versus 40 KSIs per billion vehicle miles), while for slight injuries it is 66% higher (188 vs. 123 slight injuries per billion vehicle miles). Examining the costs of injuries sustained, these are 7.4% higher for pedestrians per motor vehicle mile travelled on urban minor roads, compared to major roads. For cyclists, injury costs are slightly higher (4.2%) on major roads per mile driven, compared to minor roads. These results suggest that re-routing motor traffic to major roads in urban areas may reduce pedestrian casualties. However, if cyclist safety on major roads is not improved, shifting motor traffic from minor to major roads may result in unintended negative injury consequences for cyclists