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Summary Background Watch and wait is a novel management strategy in patients with rectal cancer who have a clinical complete response after neoadjuvant chemoradiotherapy. Surveillance of these patients is generally intensive, because local regrowth (with the potential for salvage) occurs in 25% of patients, and distant metastases occur in 10% of patients. It is unclear for how long these patients should be followed up. To address this issue, we did conditional survival modelling using the International Watch & Wait Database (IWWD), which is a large-scale registry of patients with a clinical complete response after neoadjuvant chemotherapy who have been managed by a watch-and-wait strategy. Methods We did a retrospective, multicentre registry study using a dataset from the IWWD, which includes data from 47 clinics across 15 countries. We selected patients (aged ≥18 years) with rectal cancer who had a clinical complete response after neoadjuvant chemotherapy, and who were subsequently managed by a watch-and-wait strategy between Nov 25, 1991, and Dec 31, 2015. Patients who had not achieved a clinical complete response or who had undergone any surgical procedure were excluded. The criteria used for defining a clinical complete response and the specific surveillance strategies were at the discretion of each participating centre. We used conditional survival modelling to estimate the probability of patients remaining free of local regrowth or distant metastasis for an additional 2 years after sustaining a clinical complete response or being distant metastasis-free for 1, 3, and 5 years from the date of the decision to commence watch and wait. The primary outcomes were conditional local regrowth-free survival at 3 years, and conditional distant metastasis-free survival at 5 years. Findings We identified 793 patients in the IWWD with clinical complete response who had been managed by a watch-and-wait strategy. Median follow-up was 55·2 months (IQR 36·0–75·6). The probability of remaining free from local regrowth for an additional 2 years if a patient had a sustained clinical complete response for 1 year was 88·1% (95% CI 85·8–90·9), for 3 years was 97·3% (95·2–98·6), and for 5 years was 98·6% (97·6–100·0). The probably of remaining free from distant metastasis for a further 2 years in patients who had a clinical complete response without distant metastasis for 1 year was 93·8% (92·3–95·9), for 3 years was 97·8% (96·6–99·3), and for 5 years was 96·6% (94·0–98·9). Interpretation These results suggest that the intensity of active surveillance in patients with rectal cancer managed by a watch-and-wait approach could be reduced if they achieve and maintain a clinical complete response within the first 3 years of starting this approach. Funding European Registration of Cancer Care, financed by the European Society of Surgical Oncology, the Champalimaud Foundation Lisbon, the Bas Mulder Award, granted by the Alpe d’HuZes Foundation and the Dutch Cancer Society, the European Research Council Advanced Grant, and the National Institute of Health and Research Manchester Biomedical Research Centre.

This study investigates the presentation of service logo information under partially automated driving. Drivers completed simulated drives with partial automation during which they had to detect target logo signs and react to hazards by taking over vehicle control when needed. Driver performance was measured in terms of sign detection rate, crash rate, and hazard response time. A number of factors, including sign information source, sign information load, and driver age group, were investigated. In general, our findings support the delivery of service logo information via in-vehicle display under partially automated driving, especially when the in-vehicle display occurred simultaneously with the on-road signage. Under this presentation condition, drivers were most accurate in detecting target logo signs, and showed little impairment from processing sign information as a secondary task when negotiating a hazard. Implications of the findings and future directions were discussed.

This paper presents a methodology for modeling traffic responsive (or adaptive) ramp metering in the freeway facilities method based on the sixth edition of the Highway Capacity Manual (HCM6). Currently, the HCM only provides an option to meter on-ramps as user input using 15-min average flow rates with a focus on planning-level analyses. As a result, the possibilities for simulating and modeling ramp meters with any traffic responsive ramp metering algorithm in the HCM context are limited. Moreover, the freeway facilities methodology in the HCM plays a vital role in the analysis of travel time reliability, which is built on a set of operational scenarios. However, with the lack of traffic responsive ramp metering, analysts are burdened with the task of manually entering average effective ramp metering rates for each on-ramp within the set of reliability scenarios. This process can require a substantial amount of time, in addition to increasing the potential for inaccuracy and bias in freeway and performance measure estimations. As a result, this paper is designed to fill a significant research gap by providing a method for analyzing traffic responsive (or adaptive) ramp metering, an active traffic and demand management strategy, using the core freeway facilities methodology in the HCM. The direct application of the method focuses on the MaxView metering algorithm. However, the proposed framework can be used to model any traffic responsive ramp metering algorithm. The results are validated using real-world sites located on the I-540 westbound freeway corridor in North Carolina.

This chapter describes several key tools that safety analysts use regularly at local and state agencies across the nation. The text presents a fairly new method of site evaluation for safety improvements at newly constructed or redesigned sites: the road safety audit. Conflict studies are also presented as a surrogate analysis method for hazardous site identification, or even as a posttreatment evaluation tool when crash data are not yet available. A final section discusses the various methods in which crash data can be used to improve safety on our roadways. Several prescreening methods are presented to assist in hazardous site identification. Following the site identification phase, a countermeasure selection process is provided for the engineer. The part concludes with a discussion of posttreatment analysis; specifically, the fundamentals of various crash studies and their inherent flaws, and an application of safety performance functions provided in the 2010 AASHTO Highway Safety Manual to evaluate the effectiveness of countermeasures.

In-vehicle technologies for communicating information to drivers have realized increasing use in recent years. While most attention has been paid to in-vehicle displays for presenting safety-related information, such as warnings, few studies have explored communication of non-safety-related information with in-vehicle displays. This simulated driving study examined driver performance in vehicle control and sign identification, when processing service logo information from on-road signs or an in-vehicle display. Findings suggest that in-vehicle displays, on-road signage, or both allowed drivers to identify service logos with a high accuracy and a relatively low level of workload. The use of in-vehicle displays either alone or simultaneously with on-road signage produced lower speed deviations therefore better vehicle control. Age differences were observed in vehicle control as well, suggesting the need for personalization of sign messages according to individual characteristics. This study is an initial step to examine the use of in-vehicle displays for messaging service logos as an example of non-safety-related information. The study is ongoing, and findings could provide a basis for in-vehicle display and on-road sign design for non-safety-related information.

A national-level safety evaluation of Diverging Diamond Interchanges (DDIs) in the United States was completed. This study aimed to update previous evaluations and to expand the treatment group size of previous studies to provide a more robust and reliable safety assessment of DDI deployments. For this particular treatment, it was determined that, of the observational before-and-after evaluation methodologies, the comparison group approach yields the best evaluation results. The naïve method can be influenced by outside factors that cannot be accounted for (weather, crash reporting tendencies, etc.). The empirical Bayes method is unnecessary as DDIs are installed for operational benefits, meaning that risk of selection bias and regression-to-the-mean is minimal. This study recommends a total crashes crash modification factor (CMF) of 0.633 based on the comparison group analysis of 26 DDIs in 11 states. The comparison group method was also applied to a variety of crash variables for this study. Angle, rear-end, and sideswipe crashes were found to have CMFs of 0.441, 0.549, and 1.139, respectively. Fatal-and-injury crashes provided a CMF of 0.461. Daytime and nighttime crashes provided CMFs of 0.648 and 0.638, respectively.

This study evaluated the mobility performance of pedestrian-bicycle crossing alternatives at continuous flow intersections (CFIs). CFI crossing types were compared with a standard intersect...

With advances in vehicle technologies, more information can be communicated in real-time to drivers via in-vehicle interfaces. In-vehicle messaging can be used for safety related information, such as warnings, as well as non-safety related information, such as upcoming gas stations. While much research has focused on the design of messaging safety-related information, little is known about the best practice for in-vehicle messaging non-safety-related information. The current study aimed to examine how drivers process service logos – as an example of non-safety-related information – and respond to road hazards when logos are presented on: (1) an on-road sign panel, (2) an in-vehicle display, or (3) a combination of both. It was found that drivers generally identified logos with high accuracy and low workload across the presentation conditions. Driver reactions to road hazards were slower when logos were present for processing, although the number of collisions did not increase. Although the majority of drivers self-reported a preference for the on-road presentation, the simultaneous presentation of logos on-road and in-vehicle showed a benefit on driver hazard negotiation (fewer collisions). Older drivers were less accurate in identifying logos but also had fewer collisions, likely due to them being more cautious and allocating more attention to the driving task. Findings of this study provide support for use of in-vehicle presentation of non-safety-related information in addition to existing on-road signage.

SUMMARYExosomes are secreted extracellular vesicles (EVs) carrying diverse cargos, which can modulate recipient cell behaviour. They are thought to derive from intraluminal vesicles formed in late endosomal multivesicular bodies (MVBs). An alternate exosome formation mechanism, which is conserved from fly to human, is described here, with exosomes carrying unique cargos, including the GTPase Rab11, generated in Rab11-positive recycling endosomal MVBs. Release of these exosomes from cancer cells is increased by reducing Akt/mechanistic Target of Rapamycin (mTORC1) signalling or depleting the key metabolic substrate glutamine, which diverts membrane flux through recycling endosomes. The resulting vesicles promote tumour cell proliferation and turnover, and modulate blood vessel networks in xenograft mouse modelsin vivo. Their growth-promoting activity, which is also observedin vitro, is Rab11a-dependent, involves ERK-MAPK-signalling and is inhibited by antibodies against Amphiregulin, an EGFR ligand concentrated on these vesicles. Therefore, glutamine depletion or mTORC1 inhibition stimulates release of Rab11a-exosomes with pro-tumorigenic functions, which we propose promote stress-induced tumour adaptation.

BACKGROUND: The strategy of watch and wait (W&W) in patients with rectal cancer who achieve a complete clinical response (cCR) after neoadjuvant therapy is new and offers an opportunity for patients to avoid major resection surgery. However, evidence is based on small-to-moderate sized series from specialist centres. The International Watch & Wait Database (IWWD) aims to describe the outcome of the W&W strategy in a large-scale registry of pooled individual patient data. We report the results of a descriptive analysis after inclusion of more than 1000 patients in the registry.METHODS: Participating centres entered data in the registry through an online, highly secured, and encrypted research data server. Data included baseline characteristics, neoadjuvant therapy, imaging protocols, incidence of local regrowth and distant metastasis, and survival status. All patients with rectal cancer in whom the standard of care (total mesorectal excision surgery) was omitted after neoadjuvant therapy were eligible to be included in the IWWD. For the present analysis, we only selected patients with no signs of residual tumour at reassessment (a cCR). We analysed the proportion of patients with local regrowth, proportion of patients with distant metastases, 5-year overall survival, and 5-year disease-specific survival.FINDINGS: Between April 14, 2015, and June 30, 2017, we identified 1009 patients who received neoadjuvant treatment and were managed by W&W in the database from 47 participating institutes (15 countries). We included 880 (87%) patients with a cCR. Median follow-up time was 3·3 years (95% CI 3·1-3·6). The 2-year cumulative incidence of local regrowth was 25·2% (95% CI 22·2-28·5%), 88% of all local regrowth was diagnosed in the first 2 years, and 97% of local regrowth was located in the bowel wall. Distant metastasis were diagnosed in 71 (8%) of 880 patients. 5-year overall survival was 85% (95% CI 80·9-87·7%), and 5-year disease-specific survival was 94% (91-96%).INTERPRETATION: This dataset has the largest series of patients with rectal cancer treated with a W&W approach, consisting of approximately 50% data from previous cohort series and 50% unpublished data. Local regrowth occurs mostly in the first 2 years and in the bowel wall, emphasising the importance of endoscopic surveillance to ensure the option of deferred curative surgery. Local unsalvageable disease after W&W was rare.FUNDING: European Registration of Cancer Care financed by European Society of Surgical Oncology, Champalimaud Foundation Lisbon, Bas Mulder Award granted by the Alpe d'Huzes Foundation and Dutch Cancer Society, and European Research Council Advanced Grant.

BACKGROUND: The high morbidity associated with radical resection for rectal cancer is an incentive for surgeons to adopt strategies aimed at organ preservation, particularly for early disease. There are a number of different approaches to achieve this. In this study we have collated current national and international guidelines to produce a synopsis to support this changing practice.METHODS: The databases PubMed, Embase, Trip database, national guideline clearinghouse, BMJ Best practice were interrogated. Guidelines published before 2010 were excluded. The AGREE-II tool was used for quality assessment.RESULTS: 24 guidelines were drawn from 2278 potential publications. A consensus exists for local excision for "low risk" T1 rectal cancer but there is no agreement how to stratify the risk of treatment failure. There is a low level of agreement for rectal preservation for more advanced disease but when mentioned is recommended for unfit patients or in th context of a clinical trial. Guidelines are inconsistent with respect to surveillance in node negative disease and after, complete response to chemoradiotherapy CONCLUSION: According to current guidelines and consensus statements organ preservation for rectal cancer beyond low risk T1, is still considered experimental and only indicated in patients unsuitable for radical surgery.. Follow up strategies and cN0 staging deserve attention and highlight the need for high quality clinical trials. This article is protected by copyright. All rights reserved.

The diverging diamond interchange (DDI), also known as the double crossover diamond interchange, has been a successful, if unconventional, solution used in many parts of the United States ever since its first installation in Springfield, Missouri, in June 2009. One of the challenges to agencies in planning and operating DDIs is to apply to them methodologies developed for a conventional diamond interchange. The Highway Capacity Manual 2010 (HCM 2010) provides lane use analysis models for various lane configurations. However, there is no guarantee that these models will work for DDIs. For this reason, 11 DDIs were studied nationwide ( a) to examine whether the current HCM lane use models provided accurate results for DDIs and ( b) to develop new lane use models for them if the HCM models did not work. As a result of the study, unique multiregime lane utilization models were proposed, separated by the number of approach lanes and validated by field data not used in the model development.

In recent years, transportation policy in the United States has increasingly focused on measuring and tracking performance outcomes. However, identifying how quantifiable outcomes—such as international roughness index ratings—influence less tangible outcomes—such as user satisfaction with a roadway—can be challenging. This paper outlines a method that enables researchers to compare stakeholder perceptions of assets with actual field-measured data for roadways. More than 350 residents in six locations in the state of North Carolina were surveyed about how those residents perceived and prioritized the roadway assets managed by the North Carolina Department of Transportation. Using a method termed “roadway reviews,” researchers asked participants about state-maintained roads as the participants were driven on those roads in real time; these surveys were supplemented with focus groups. In addition to identifying how well asset conditions on roadway segments aligned with the basic expectations of roadway users, researchers determined how these ratings compared with field measurements for the segments and captured how participants ranked the importance of specific roadway assets for overall condition, safety, and appearance. The findings will be used to improve asset management practice and will be integrated into the North Carolina Department of Transportation’s annual Highway Performance Monitoring System reports.

Even though diverging diamond interchanges (DDIs) have been the subject of research for more than a decade, the effort to standardize interchange signal timing has developed only recently. A three-factor fully crossed experiment was conducted to investigate the influence of crossover spacing and increased volumes on the performance of DDI phasing schemes. PTV Vistro software and the dynamic bandwidth assessment tool were used to optimize the split, cycle length, and offset of each of the 72 treatments. PTV Vissim software was used to collect microsimulation data. Mean interchange delay and mean stops per vehicle were selected as measures of effectiveness. Pairwise comparisons were used to determine whether an existing preferred phasing scheme could minimize delays or stops under three cases: ( a) given spacing and increased volume, ( b) given volume independent of spacing, and ( c) given spacing independent of increased volume. The data revealed that a two- or three-critical-movement phasing scheme usually resulted in the lowest mean interchange delay and the fewest stops. Overall, the results provide an initial signal timing scheme for practitioners given a crossover spacing, an increased volume, or both. Future work will include exploring low volumes, balanced interchange volumes, and their effects on the four-critical-movement phasing scheme, as well as the effect of closely spaced adjacent intersections.

Exosomes are secreted extracellular vesicles carrying diverse molecular cargos, which can modulate recipient cell behaviour. They are thought to derive from intraluminal vesicles formed in late endosomal multivesicular bodies (MVBs). An alternate exosome formation mechanism, which is conserved from fly to human, is described here, with exosomes carrying unique cargos, including the GTPase Rab11, generated in Rab11‐positive recycling endosomal MVBs. Release of Rab11‐positive exosomes from cancer cells is increased relative to late endosomal exosomes by reducing growth regulatory Akt/mechanistic Target of Rapamycin Complex 1 (mTORC1) signalling or depleting the key metabolic substrate glutamine, which diverts membrane flux through recycling endosomes. Vesicles produced under these conditions promote tumour cell proliferation and turnover and modulate blood vessel networks in xenograft mouse models in vivo. Their growth‐promoting activity, which is also observed in vitro, is Rab11a‐dependent, involves ERK‐MAPK‐signalling and is inhibited by antibodies against amphiregulin, an EGFR ligand concentrated on these vesicles. Therefore, glutamine depletion or mTORC1 inhibition stimulates release from Rab11a compartments of exosomes with pro‐tumorigenic functions, which we propose promote stress‐induced tumour adaptation., Release of Rab11a‐positive exosomes with distinct cargos and increased pro‐tumorigenic functions is dependent on glutamine levels and Akt/mTORC1 signalling.

Diverging diamond interchanges (DDIs) are relatively new in the United States, and signal coordination between the crossovers and adjacent intersections is challenging. This paper provides a method for remotely fine-tuning offsets for a DDI and its adjacent intersections. The proposed method uses the dynamic bandwidth analysis tool (DBAT). The tool uses actuated phase times from the signal controller to optimize the dynamic bandwidth on the basis of that entry data set. Four performance measures evaluated the proposed method: delay, stop severity index, maximum queue, and vehicle trajectory plots. The test results confirmed that DBAT provided a better offset solution than other bandwidth optimization tools that generally optimized programmed bandwidth only and did not account for early return to green caused by skipped or gapped-out movements. Under the DBAT offsets, delay for the through movements on the corridor decreased by 52.8% for northbound vehicles and 46.83% for southbound vehicles. The average delay reduction over all measured paths for uncongested and congested scenarios was 13.88% and 3.50%, respectively. The proposed method and workflow can significantly reduce the offset retiming work process. Normally, this manual process takes more than a day, but the proposed method can be completed in less than an hour without visiting the study site. Furthermore, the proposed method can coordinate any set of movements, as well as multiple travel paths. The authors believe that the proposed method and workflow will significantly help both retiming and new timing of arterial signal coordination along DDI corridors and other signal systems.

Diverging diamond interchanges (DDIs) have swept the country as an innovative interchange system since the original U.S. installation in Springfield, Missouri, in 2009. Although the DDI provides many benefits, prior research identified some operational challenges found at some of the first DDIs built around the country. This study explored the challenge of limited capacity for the right turn at the DDI ramp terminal intersection and associated queue spillback concerns that have been observed at several sites. The study investigated the impact of five geometric treatments at a DDI’s right-turn exit ramp, including a channelized turn lane with an auxiliary lane, dual right-turn lanes, right turn on red (RTOR), dual right-turn lanes with RTOR, and a slip lane. The results showed that any treatment that decreased the green-to-cycle length ratio for the right turn from the exit ramp simultaneously reduced queues at the exit ramp and the outbound through movement at the crossover. However, treatments that did not also increase the capacity of the outbound through movement at the downstream adjacent intersection resulted in increased queues at that movement. The study concluded that the design of the DDI must be considered in the context of the entire corridor. To provide the full extent of congestion relief that is possible with a DDI, consideration of the geometrics of downstream, closely spaced, adjacent intersections must be included from the earliest planning stages.

A diverging diamond interchange (DDI) is an innovative interchange design that is being used with increasing frequency in the United States because of the ability to use existing right-of-way and infrastructure frequently. This paper documents the state of the practice in DDI signal phasing with principles established in the Signal Timing Manual, namely, that it uses consistent phase numbering in a logical format to describe each of the phasing concepts being considered and discussed in this paper. Although some literature exists on several methods of signal phasing for DDIs, inconsistency in the reporting leaves practitioners scratching their heads when attempting to decipher what phasing scheme to use. In response, three fundamental phasing schemes are presented, one each for volume patterns with two, three, and four critical movements. Each scheme is described with a consistent naming convention, and, when possible, each is manipulated to provide varying coordination strategies. In addition, concepts such as use of actuation and barriers to improve coordination are described, and methods for reducing lost time are introduced. Other supplemental information related to preemption and pedestrians is discussed briefly. In conclusion, practitioners are given some basic guidance on when one phasing scheme may be more appropriate than another.

This paper outlines the process for selecting sites to perform counts on transportation facilities in the context of establishing a nonmotorized traffic volume counting program. Many agencies are well practiced in collecting motor vehicle traffic counts and estimating annual average daily traffic volumes for motor vehicles on the basis of knowledge founded on years of research and experience. Selecting sites is one component of developing a consistent system for quantifying nonmotorized travel so bicycle and pedestrian volumes can ultimately feed into tools to measure existing trends and model future increases in nonmotorized trips at site, corridor, and regional levels. The outcome of collecting count data can ultimately assist in evaluating facility usage over time, better inform the project prioritization process, and provide evidence to support nonmotorized facility inclusion through Complete Streets planning and improve planning for active transportation. This paper outlines the goals of a nonmotorized traffic monitoring program and objectives of the site selection process. From the experience of a pilot project conducted by the North Carolina Department of Transportation, the site selection method details the following components: gathering potential sites, conducting a site visit, gathering additional data needed to inform the decision-making process, and ultimately selecting sites and developing an equipment inventory.

This research considered the unique challenges for pedestrians and bicyclists at superstreet intersections and recommends crossing alternatives for both users. For pedestrians, the options included the diagonal cross, median cross, two-stage Barnes Dance, and midblock cross. For bicyclists, the options included the bicycle U-turn, bicycle use of the vehicle U-turn, bicycle direct cross, and midblock cross. These options were analyzed through microsimulation on the basis of average stopped delay, average number of stops, and average travel time per route. Various parameters were analyzed for each crossing configuration, including two signal cycle lengths (90 and 180 s), two signal splits (60/40 and 75/25), two signal offset designs (vehicle platoons arrive simultaneously and at various offset times), and two midblock distances (600 and 800 ft). The recommended pedestrian crossing was a combination of the diagonal cross with the midblock cross. The parameters that decreased travel time for pedestrians were a 90-s cycle length, a 60/40 signal split, and an offset signal design in which the vehicle platoons arrived at different times. For bicyclists, the bicycle direct cross resulted in the lowest average number of stops and the lowest average travel time, whereas the vehicle U-turn showed the lowest stopped delay. The parameters that decreased travel time for bicyclists included a 90-s cycle length and the vehicle platoons arriving at different times. The recommended options for bicyclists at a superstreet were a combination of the bicycle direct cross and the midblock cross.

Double crossover diamond (DCD) interchanges, also known as diverging diamond interchanges, are popular and promising alternative interchanges that are increasingly being implemented nationwide. One unique feature of a DCD interchange is that through movements on the arterial road have to cross each other twice to complete their movements, while enabling left-turn movements from the arterial to the freeway to proceed without stopping at the downstream intersection. Consequently, interchanges with heavy left-turn movements are good candidates for DCD implementation. This unique feature of a DCD interchange means that there is a need to research lane utilization at the upstream approach intersection of DCD interchanges, as the lane use could be unbalanced. This unbalanced lane utilization could have a significant effect on operations at the first crossover and the interchange as a whole. This study examined lane utilization factors provided in the Highway Capacity Manual 2010 (HCM) for conventional diamond i...

Lidar is becoming increasingly popular across the United States, and state transportation agencies are adopting this technology for practical uses in transportation-related applications. This trend can be seen in the growing number of agencies acquiring lidar scanners and contracting lidar services. The primary factors behind this trend are that (a) surveyors, engineers, and technicians are becoming more educated about and increasingly open to lidar and its applications and (b) lidar is potentially more cost-effective than traditional surveying technologies. Lidar can provide transportation agencies with the benefits of safety, data collection productivity, cost-effectiveness, applicability, high levels of detail, and technological advancement. Many of the more practical uses and benefits of lidar have come to fruition in recent years, and transportation agencies have been more open to its use. However, little more than anecdotal evidence supports when a specific lidar platform should be applied for various applications rather than a traditional surveying method. Decision makers in geomatic and surveying departments that use lidar must regularly weigh the options of which surveying method to use for specific projects and base decisions on performance tradeoffs. The methodology presented in this paper aims to provide guidance on how agencies may determine whether lidar can be practically used within their organizations. The aspects and performance measures outlined for effective deployment of lidar equipment or contracted services should be systematically considered.

Transportation agencies have made significant strides to reduce collisions and increase capacity along strategic highway corridors. Efforts have led to the implementation of many different access management techniques along corridors, such as installing medians versus two-way left-turn lanes and closing median openings. Businesses along these corridors have indicated their concern that these new designs will have a negative economic impact on their business because of the lack of direct access to their properties. The objective of this study was to quantify the business perceptions of median treatments on businesses adjacent to multilane highways. Owners of businesses along treatment corridors viewed median installations with a more positive outlook following implementation of the median than they did prior to the installation. The performance of treatment sites in terms of reported impacts on business revenues indicates that there is no direct evidence of negative economic impacts due to median installations.

In October 2011, the North Carolina Department of Transportation conducted a roadway review with a randomly recruited sample of North Carolina residents and community leaders. More than 300 people from 61 communities participated in the surveys, which were held in six locations: Asheville, Burlington, Charlotte, Jonesville, Rocky Mount, and Wilmington. The purpose of the roadway review was twofold: to determine the expectations for the condition of North Carolina highways and to identify the features that North Carolinians believe are most important on different types of highways. Surveys were completed during both daytime and nighttime hours and covered many roadway maintenance aspects, such as pavement, landscaping and mowing practices, signage, retroreflectivity, and shoulders. Regression equations are also provided to predict the overall satisfaction of condition, safety, and appearance by each individual roadway type.

This study compared output from mobile inventory data collection vehicles to manually collected data techniques with a focus on two-way communications primarily through the submission of a sample data set to be analyzed prior to the submission of a full data set. The interim submittal and feedback to the vendors based on that resulted in a marked improvement in data quality for 5 of the 28 assets studied. After feedback, it is apparent that highway data collection vendors can accurately locate the vast majority of assets, with the primary exception being those that are occluded by vehicles or surrounding landscaping, such as those assets in the median. Along with the locations of assets, vendors showed promise at collecting many of the feature descriptions such as asset type and condition. Many of the elements (location, type, etc.) for a particular asset type that created collection difficulty were only problematic for a particular vendor, which suggests that further improvements may be achieved ...

Arterials across the United States are experiencing far too many collisions. Agencies tasked with improving these arterials have few available effective solutions. Superstreets, called restricted crossing u-turns by the Federal Highway Administration (FHWA), are part of a menu of unconventional arterial intersection designs that may provide a promising solution. Up to this point, there is little valid information available on the safety effects of superstreets, as study results have been from basic analyses that only account for traffic volume changes. The purpose of this research was to determine the safety effects of the unsignalized superstreet countermeasure on existing arterials in North Carolina. The safety study involved traffic flow adjustment, comparison-group, and Empirical Bayes analyses of 13 unsignalized superstreet intersections in North Carolina. The superstreets have been installed in the last few years across the state as opportunities presented themselves, but not necessarily at the most hazardous sites. The unsignalized superstreet countermeasure showed a significant reduction in total, angle and right turn, and left turn collisions in all analyses. Analyses also showed a significant reduction in fatal and injury collisions. The authors recommend that future analysts use a crash modification factor of 46 percent when considering the conversion of a typical unsignalized arterial intersection into a superstreet. Language: en

This paper evaluates the structural integrity and safety performance of weathered steel beam guardrail (WSBG) in North Carolina. WSBG is a popular alternative to galvanized steel guardrail (GSG) in that it is an aesthetic solution that blends in with the surrounding natural environment. A New Hampshire study, however, found that WSBG deteriorates more quickly. That study prompted an FHWA recommendation discouraging the use of WSBG across the country. This paper describes a comprehensive study of all WSBG installations in North Carolina, where weather conditions and deicing practices are generally much less severe than in New Hampshire. The research results did not show any trends of deteriorating thickness as a function of guardrail age (the oldest installation was almost 30 years old), elevation (the tallest installation was 4,200 ft), and annual average daily traffic (the highest traffic volume was 27,000 vehicles per day). The WSBG at all 25 test sites was shown to be above AASHTO minimum thickness specifications of 0.096 in. at a 95% confidence level. From a safety perspective, the research results suggested a lower percentage of injury collisions at WSBG installations relative to GSG installations at comparison sites, although low crash sample sizes made a more robust comparison difficult. Overall, this research suggests there are no structural concerns about using WSBG in North Carolina. The findings of this study may have broader policy implications for other states.

Five cues were evaluated with respect to their usefulness in directing the headings of pedestrians who were blind during street crossings. The study was conducted at a simulated crosswalk, with the angle of the crosswalk varied relative to the approach and direction of the slope of the ramp. Three cues worked well over the distance equivalent to the width of a six-lane road.

Accurately aligning to a crosswalk is an important component of safe street crossing for pedestrians who are blind. Six alignment cues were evaluated in a simulated crosswalk environment in which the angle of the crosswalk was not always in line with the slope of the ramp. The effectiveness of each cue is reported and implications are discussed.

The primary objective of this research effort was to compare roadside data collected by typical manual methods - on foot and often requiring traffic control - to data collected by manned data collection vehicles moving with traffic. The research team provided an unbiased comparison of multiple vendors collecting many types of data on various roadway elements including curb, guardrail, signs, pavement markings, and roadway geometry. These data are frequently collected and used by many units within a highway agency such as roadway maintenance, safety, and operations. The research team provided a catalog to each vendor prior to running a 144.8 km (90-mile) test course. The catalog provided a map of the course, a list of each roadway element to be collected, and specific details on how each data element was collected manually. The test course included a variety of highways across a portion of central North Carolina. Multiple data collection companies were given the opportunity to participate, with six actually agreeing to partake and submit data. No vendors supplied sign retroreflectivity data, one submitted pavement marking retroreflectivity data, three submitted roadway geometry data, and five submitted data on roadside elements. The results showed that mobile data compared reasonably well to manual data for most of the desired variables. Mobile data on elements in close proximity to the edge of pavement matched manual data better than elements further from the road. Counts of specific elements were a better fit between mobile and manual data than elements that needed qualitative judgments. Among the major lessons learned is the need for crystal clear specifications before embarking on a mobile data collection program and the desirability of having vendors submit data for a small sample of roadway before embarking on the bulk of a data collection effort.

This paper presents work conducted as part of an evaluation of the Ticketing Aggressive Cars and Trucks (TACT) III program of the North Carolina Highway Patrol. The goal of the TACT program is to reduce the contribution of aggressive driving behaviors to crashes involving commercial motor vehicles. In the present study, camera-based detection methods were used to identify the incidence of following too closely within the context of prevailing commercial motor vehicle and passenger vehicle volumes, speeds, and lane position both before and during TACT program enforcement operations. The data suggest that enforcement under the TACT program may have differential effects on the following distances of cars and trucks. An increase in the following distances of commercial motor vehicles was observed in the rightmost lane of an Interstate facility. A slight decrease in the speeds of commercial motor vehicles was also observed during the enforcement period, but no significant changes in speeds or vehicle following times were observed for passenger vehicles. The results indicate that the methodology developed is sensitive and is able to detect changes in driver behavior. It may thus become a potential alternative strategy for evaluation of the TACT program. The use of roadside instrumentation further enables future applications for automated driver feedback, in which following too closely and speed violations may be detected automatically and the information relayed to the driver in an infrastructure-to-vehicle context like that for dynamic speed signs. Automated methods developed as part of this research could also be used for automated enforcement in future applications.

This paper describes the development and implementation of the conflict-based assessment of pedestrian safety (CAPS) methodology for the evaluation of pedestrian accessibility at complex intersections. Significant research has explored pedestrian access to modern roundabouts and other complex intersections, and a significant focus has been placed on accessibility for pedestrians who were blind. A majority of these studies relied on actual street crossings by study participants under the supervision of a trained orientation and mobility specialist. These crossing studies quantified risk from a measurement of intervention events, in which the orientation and mobility specialist had to physically stop the participant from crossing. Although such studies provide useful data on the crossing risk at a particular intersection, street crossings can be dangerous to the study participants and are time-consuming and expensive to conduct. The CAPS method emphasizes the use of conflict-based safety factors to quantify risk in a framework compatible with indicator studies. This method relates pedestrian crossing decisions to advanced measurements of vehicle dynamics to estimate lane-by-lane conflicts and identifies the grade of conflict on the basis of a five-criterion rating scale. The CAPS framework was applied to a study of crossings by blind pedestrians at a multilane roundabout. The resulting risk scores were calibrated from the actual orientation and mobility interventions observed during the study. The calibrated CAPS framework correctly matched all (high-risk) orientation and mobility intervention events and further identified other (lower-risk) pedestrian–vehicle conflicts. The CAPS framework provides a more efficient, objective, and consistent safety assessment of pedestrian crossings in a research context, without the need for pedestrians to step into the roadway.

Arterials across the United States are operating inefficiently and are becoming increasingly congested because of growing traffic demand. Agencies tasked with improving these arterials are running out of good solutions. Superstreets, called restricted crossing U-turns by FHWA, are part of a menu of unconventional arterial designs that may provide promising solutions. Up to this point, little valid information exists on the operational effects of superstreets because study results have been from macroscopic analyses and simulations of hypothetical arterials. The purpose of this research was to determine the operational effects of the superstreet treatment on existing signalized arterials in North Carolina. The operational analysis involved calibrating and validating VISSIM models of three existing signalized superstreets in North Carolina; two isolated intersections and one five-intersection superstreet corridor. After some adjustments, the team produced VISSIM models that provided travel times within an acceptable range of the field data collected. Results from the three calibrated VISSIM models were compared with results from models of equivalent conventional sites at various volume levels with travel time as the primary measure of effectiveness. The superstreet outperformed the conventional design at each location studied and reduced the overall average travel time per vehicle traveling through the intersection. The travel time savings and extra capacity at higher volumes can buy agencies more years of acceptable operation before intersection improvements, or even interchanges, are necessary.

The effects of a mobile automated speed enforcement system in Charlotte, North Carolina, were examined. Limited focus groups were conducted to characterize resident and professional attitudes, opinions, and beliefs regarding such a speed program. Overall, opinions were positive. The system, consisting of three mobile units, was implemented along 14 corridors. Two separate analyses were conducted on data collected from January 2000 to December 2005. Findings from a previous study done for the North Carolina Governor's Highway Safety Program were updated. The first, and primary, analysis was a before-and-after analysis of collisions. This study used Hauer's comparison group methodology. Three different collision data sets were analyzed: total collisions, data accounting for regression to the mean, and data for five heavily enforced corridors. On the basis of the analysis, the impact of regression to the mean appears to be negligible. The results indicate that the camera program likely reduced collisions in corridors with automated enforcement. The second analysis observed whether compliance with posted speed limits was enhanced. Mean speeds, median speeds, 85th percentile speeds, and percentages of drivers more than 10 mph over the speed limit were analyzed. The analyses found speed reductions caused by the camera program. On the basis of these findings, it was recommend that the City of Charlotte continue the automated speed enforcement program. Other agencies considering speed camera programs can benefit from the knowledge gained in Charlotte.

Superstreets are an unconventional at-grade intersection design that have significant potential to help with safety and delay. The purpose of this paper is to formally evaluate residential, commuter, and business owner opinions of superstreets across North Carolina through feedback from three separate surveys. Findings from each of the surveys provide interesting feedback. Residents living near superstreets agree the design helps them travel more safely through the intersection. Commuting drivers perceive superstreets to be more difficult to navigate, but feel strongly about savings in travel time and reductions in numbers of stopped vehicles. Business reactions varied greatly depending on the ability to make direct left turns from the arterial. In general, more business managers feel superstreets negatively impact business growth and operations. Based on the opinions of adjacent business owners/managers, access and confusion were identified as key problems in retaining the number of regular custo...

When some two-lane roads with 55 mph speed limits are widened to four through lanes, curb and gutter is installed to address issues such as access control, difficult terrain, and limited right-of-way. Posted speed limits along such highway segments are typically decreased to 45 mph in North Carolina because of guidance in the AASHTO Green Book and elsewhere that vertical curbs should not be placed next to high-speed lanes. Although much money is spent to improve such roadways, the results may be viewed negatively by the public, design professionals, and law enforcement personnel. Drivers may be unhappy about getting tickets or driving more slowly, designers are unhappy about being blamed by the public, and police are unhappy about the increased enforcement burden. To help resolve such a dilemma, in this research the team collected relevant data such as speeds and collisions on four-lane road sections with curbs that have 45 or 55 mph speed limits and nontraversable medians or two-way left-turn lanes. The team found that the speed limit does not seem to make an important difference in collision rates or severities for the roads the team examined. The higher speed limit also made relatively small differences in the mean speeds and speed variances observed. Considering all results, the researchers recommended that the North Carolina Department of Transportation continue its current policy of allowing 55 mph speed limits on four-lane roads with curbs on a selective, case-by-case basis.

Previous studies have shown that roundabouts, especially multilane roundabouts, pose accessibility challenges to pedestrians with vision impairments, in part because of a lack of yielding by drivers, especially on multilane roundabout exit legs. In this study, a driving simulator was used to assess three different treatments in regard to their propensity for increasing the driver yielding rate. These treatments were the relocation of the stop bar and crosswalk away from the beginning of the exit leg and two types of beacons, namely a pedestrian hybrid beacon (PHB) and a rectangular rapid flashing beacon (RRFB). The study showed that the installation of any kind of beacon (PHB or RRFB), with or without crosswalk relocation, increased driver yielding rates significantly. Relocating the crosswalk did not provide a significant increase in the driver yielding rate for the base case, but appeared to enhance further the effectiveness of the PHB and RRFB treatments. The results of using an eye tracker on drivers to track their gaze pattern while exiting the roundabout showed that having a beacon installed with crosswalk relocation increased drivers’ attention on the beacon and on the pedestrian along the road. However, some of the participants failed to see and react to the pedestrian treatments and thus caused concern about the visibility of these treatments at the roundabout exit leg.

This report is intended to provide practitioners with useful information related to establishing safe crossings at roundabouts and channelized turn lanes for pedestrians with vision disabilities. The specific focus areas of the report provide guidance on: identifying under what conditions pedestrians with vision disabilities may experience problems with crossing performance; tying treatment solutions to specific crossing challenges faced by the visually impaired pedestrian population; conducting pedestrian/vehicle studies that help identify performance problems and appropriate treatment strategies; quantifying pedestrian accessibility at a particular crossing; presenting findings from selective field studies performed through this research; developing approaches for extending research findings to other locations; and discussing implications for the practitioner in terms of treatment selection and facility design. The results of this research will be useful to engineers, the accessibility community, policy makers, and the general public to aid in understanding the specific challenges experienced at these facilities by pedestrians with vision disabilities. It is only through the understanding of the components of the crossing task and the particular challenges involved that solutions can be developed, installed, and evaluated appropriately.