Texas Department of Transportation

Street space reallocation measures, such as Low Traffic Neighbourhoods (LTNs), have attracted substantial controversy in the UK and elsewhere, for instance around reported poor engagement with residents and local actors. However, limited attention has been given to the political-economic context shaping scheme implementation, such as the impacts of reduced resources or the use of short-term, contingent funding. Based on 37 interviews with officers and councillors who implemented or sought to implement LTNs in 12 English local authorities, and part of a larger project investigating the impacts of LTNs in London, this paper addresses the gap. It shows how challenges to design, engagement and delivery are often linked to funding scarcity and processes of projectification, advancing the literature on transport governance and controversy. • Limited attention has been paid to the political-economic context shaping the implementation of Low Traffic Neighbourhood schemes • Existing approaches to funding active travel schemes, which in the context of austerity urbanism exacerbate the negative aspects of projectification, affect the success of schemes • Schemes require significant investment in terms of staff time and knowledge • They would also benefit from more funding to deliver greening aspects • The effects of austerity and projectification are exacerbated within uneven geographical areas • Local authorities with access to additional internal resources were able to implement and sustain schemes and learn from mistakes • Less resrouceful local authorities saw initial failures translate into increasing challenges for future schemes and an overall inability to implement successfully

Traffic crashes remain a major threat to road safety, with many crash-related casualties and large economic losses occurring every year. Generally, crashes are complex events involving interactions between a wide range of factors, including those related to the driver, vehicle, roadway, traffic, and weather at the time and place of the crash. Whereas numerous road safety studies investigated the contribution of various factors to crash frequency and severity, a better understanding of the combined effect of pavement condition on crash occurrence is needed to assist pavement managers identify appropriate pavement safety improvement projects. Pavement surface condition factors are of particular interest to highway agencies because they fall directly within their control and can be addressed through maintenance and rehabilitation (M&R) projects. This study introduces crash susceptibility as a new parameter useful for incorporating safety in pavement management decisions. In this study, crash susceptibility is defined as the probability of a crash occurring on any given pavement segment within a given year. Logistic regression was employed to estimate the likelihood of crash occurrence on asphalt concrete pavement (ACP) with and without surface treatment (ST) or seal coat as a function of the pavement condition (roughness, macrotexture, skid resistance, and distresses), while considering traffic volume, road geometrics, and environmental conditions. This study utilized three years (fiscal years 2021–2023) of crash, pavement condition, and site condition data from Texas. The results show that for both asphalt pavement types, increased roughness contributes to higher crash susceptibility, whereas increased skid resistance contributes to lower crash susceptibility. However, the effects of these pavement conditions are more significant on pavements without ST or SC. This study also shows that higher macrotexture is associated with a reduction in crash susceptibility for pavements without ST or SC. Of the individual pavement distresses examined, only potholes show a significant increase in crash susceptibility, and this effect is observed only for pavements with ST or SC. Other pavement distresses, including rut depth, raveling, flushing, cracking, failures, and distress score, were found to have no significant impact on crash susceptibility. Highway agencies can use this study to assess the influence of pavement surface conditions on crash susceptibility and to support data-driven decisions for roadway maintenance and safety improvements.

The mitigated and fenced section of State Highway 100, extending from Laguna Vista to Los Fresnos, includes five wildlife crossing structures and 16 modified cattle guards (also called wildlife guards) installed to mitigate ocelot road mortality. Bridge grate and pipe wildlife guards were deployed at vehicle entries, and we evaluated their effectiveness in preventing meso-carnivores and ungulates from entering the roadway through the fence gaps from April 2020 to 2024. Wildlife guards collectively were >82% effective in repelling ungulate attempts to enter the roadway, while only 16.64% of meso-carnivore attempts were repelled. The pipe wildlife guard (PWG) design repelled 86.79% of ungulates and 18.83% of meso-carnivore attempts to enter the roadway. In comparison, the bridge grate wildlife guard (BGWG) design repelled 81.51% of ungulates and 15.81% of meso-carnivores. Our results indicate that PWG and BGWG effectively prevented ungulates from entering the roadway through fence gaps. Although both PWG and BGWG had low repulsion rates for meso-carnivores, PWG was found to be more effective at preventing meso-carnivores from entering the roadway.

As the asphalt pavement industry evolves, advanced methodologies for pavement design are becoming essential. Tools like the Texas mechanistic-empirical flexible pavement design system are vital for effective pavement design. The program requires repeated load permanent deformation (RLPD) test parameters, α and μ, as inputs to determine rutting behaviors. However, the RLPD test, a cyclic loading test that simulates traffic loads and is generally favored in pavement design programs, is costly and time-consuming. In contrast, the mix design process tends to use faster and simpler performance tests, such as the ideal rutting test (IDEAL-RT), which estimates rutting potential with less expenses. Thus, the industry faces two distinct sets of performance tests for mix and pavement design processes. This study aims to bridge this gap by deriving RLPD parameters from the IDEAL-RT. Both the RLPD test and IDEAL-RT were conducted on various asphalt mixes sampled from different climatic regions across the United States. The results reveal a strong correlation between the IDEAL-RT and RLPD test outcomes. Specifically, relationships between the RTIndex from IDEAL-RT and RLPD parameters were established using power-law models derived through regression analysis and demonstrated good agreement with the data. Ultimately, this study effectively bridges the gap between mix designs and pavement designs, facilitating early prediction of pavement performance during the mix design stages.

The concept of air voids (AV) continues to be used as the primary control parameter in the mix design of hot mix asphalt (HMA). AV are estimated from the bulk specific gravity and the maximum specific gravity. Their accurate estimation is very important, since samples for various tests are compacted to target AV, which are calculated on their basis. This study explored the impact of gradation and asphalt content on the AV, effective air voids (EAV), and apparent and maximum specific gravity of a fine- and a coarse-graded HMA. Samples were tested for bulk specific gravities, apparent and maximum specific gravities, rutting tolerance index, and cracking tolerance index. The results indicate that significant differences exist between AV measured by the different procedures and EAV, and that the differences are greater for a coarse-graded mix than for a fine-graded mix. Major sample-to-sample variations exist for the apparent specific gravity values, which could be significantly different from the generic maximum specific gravity values that are used for each mix. This has a significant impact on the estimation of AV and variability of test results. A strong correlation between the ratio of EAV and AV is presented. Based on the results of this study, and because EAV are strongly correlated to permeability and aging, it is recommended that the concept of EAV be considered in the regular mix design of coarse-graded HMA.