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This research effort is part of a collaborative research project between the North Carolina Department of Transportation (NCDOT) and North Carolina State University’s (NCSU’s) Institute for Transportation Research and Education. As North Carolina confronts increasing transportation budget deficits, reliable revenue generating mechanisms will become invaluable to preserve the state’s transportation infrastructure. Understanding public perception of current and potential transportation funding mechanisms will be important for NCDOT and other decision-makers. The primary objective of this research is to not only summarize North Carolinians’ perceptions about transportation funding mechanisms, but to also explore their determinants and potential implications. This research builds from prior findings in 2019 and 2020 and seeks to further expand understanding of public opinions about transportation. Through the continuation of a longitudinal survey and the addition of twelve focus groups, several findings emerged regarding North Carolina residents’ perceptions of transportation funding and electric vehicles. Overall, respondents support increasing transportation funding and feel strongly that funding should be increased. Respondents preferred that transportation funding be supported through a general increase in the state sales tax, however, there is some support for increase in annual registration fees and the introduction of a new mileage-based usage fee. Regarding transportation funding, there are few major differences between demographic groups. However, when it comes to perceptions of electric vehicles, there are some notable differences between political ideological groups, age groups, and ethnic groups.

NCDOT RP 2019-28, Safety for all road users is a key concern as Connected and Autonomous Vehicle technologies develop and reach the testing phase. One key concern is the change to two-way communication that often occurs in traditional pedestrian-vehicle interaction. This project focused on three key aspects to this issue. First, a prototype autonomous shuttle system was expanded to include additional communication features in a lightbar as well as more advanced pedestrian detection systems. Secondly, multiple detection methods were trained and tested using traditional datasets as well as a new dataset including occluded pedestrians. Finally, a survey was conducted to determine how well pedestrians understand specific static or dynamic lightbar patterns as an additional communication tool for CAVs. This project tested multiple pedestrian detection methods and developed improved methods with increased accuracy and reduced latency. The EcoPRT vehicle was able to incorporate the improved detection method, however the training image set included multiple camera perspectives and the method could likely be applied to infrastructure-based detection systems. Additionally, the project developed a body part-based method which detects head, arms and legs of pedestrians in order to improve the overall detection of pedestrians when they are partially occluded. The project also developed a database of occluded pedestrian images which can be used for training or testing other new methods addressing this issue. Finally, the project examined multiple methods for signaling the CAV intent to pedestrians using fixed or moving lightbars. Respondents struggled to correctly identify the message communicated by the lightbar in cases where multiple movements are expected (such as locations with potential turning movements) but identification improved in more constrained environments.

NCDOT RP 2019-25, In North Carolina, wrong way driving (WWD) crashes are one of the most severe traffic crashes that often result in a fatality or serious injury since they involve head-on or opposite direction sideswipe crashes at high speeds. To minimize the occurrence of WWD crashes, the North Carolina Turnpike Authority (NCTA), which is a unit of the North Carolina Department of Transportation (NCDOT), deployed a wrong way vehicle detection system along the Monroe Expressway in 2018. The system can automatically detect wrong way vehicles at mainline stations and inform traffic management center operators. This project evaluated the effectiveness of wrong-way traffic control devices installed at the ramp and mainline locations along the Monroe Expressway. A comprehensive literature search was conducted to summarize the state-of-the-practice of WWD crash modeling, detection, and prevention. Real-world traffic data including traffic volume, traffic control devices present, geometry and configuration of interchanges were employed for identifying the relationship between the frequencies of wrong way incidents and facility characteristics. During the study period of approximately 1.5 years of data collection, there were 13 actual WWD events, of which five wrong way movements originated from the roundabout parclo interchanges on the Monroe Expressway. In addition, this project collected statewide data on partial cloverleaf interchanges to assess the risk for wrong way movements. It was found that the partial cloverleaf interchange configuration was associated with the highest number of WWD activities, and factors that affect the risk of WWD mainly include: entrance and exit ramp traffic volume and control type, divided or undivided exit ramp, median cut turn access, left-turn perpendicular turning distance, skew angle, and distance between ramp terminals.

The NCDOT has made significant strides to reduce collisions and increase capacity along, strategic highway corridors across the state. Efforts have led to the implementation of many, different access management techniques along corridors, such as installing medians versus, two-way left turn lanes, using leftovers, closing median openings, and installing superstreets., The Department has continued to receive comments from businesses along these corridors, indicating their concern that these new designs will have a negative economic impact because, of the lack of direct access to their properties. This study employs a perception based survey, technique with the use of comparison sites to create a pseudo before-after study. Owners of, businesses along treatment corridors viewed access management techniques in a more positive, light than the perceptions of those on comparison sites. Their similar performance in terms of, business revenues indicates that there is no direct evidence of negative economic impacts due, to access management installations.

Work performed in this research project was in support of the effort by the North Carolina Department of Transportation to develop criteria to discern the need for undercutting soft soils and the adequacy of the subgrade after stabilization measures are implemented. The work was specifically focused on performing field testing and collecting data at a site located in the North Carolina Piedmont geologic area. Three test pads were constructed on comparable subgrade conditions with subgrade stabilization measures that included the use of select fill material and geosynthetic reinforcement coupled with a relatively thin layer of Aggregate Base Coarse (ABC). Field loading was applied using 1000 passes of a loaded construction truck. Several parameters were monitored during loading including stresses, deformation, and moisture and suction levels. A fourth pad was also constructed to test lime stabilization; however loading of this pad was not performed since the lime used for stabilization did not meet NCDOT’s specifications. A surface profiler (Lidar-based surveying) was used at periodic intervals to monitor plastic deformation and wheel path rutting with loading cycles. The field testing also included collection of data from Light Weight Deflectometer (LWD) and Dynamic Cone Penetrometer (DCP) to assess subgrade properties. Results indicated that the measured vertical stress near the interface of the subgrade for the geosynthetics-reinforced sections initially increased, but then decreased with increasing number of truck passes This decrease was attributed to progressive densification of the aggregate base course and the mobilization of the reinforced layer tensile strength. The reinforced sections experienced surface deformation on the order of 0.5-0.7 inches and the select fill-stabilized section showed a 1.2 inches of deformation after 1000 truck passes. In addition to the field data, two models were developed for the estimation of the resilient modulus (Mr) on the b

2014-32, The Institute for Transportation Research and Education at North Carolina State University conducted a follow-up study to, a previous North Carolina Department of Transportation (NCDOT) project, comparing mobile inventory data collection, vehicles to manually-collected data techniques. In the previous studies, sign retroreflectivity readings were either, captured with low degrees of accuracy or not captured at all. The follow-up study focused mainly on automated sign, retroreflectivity capture, but also looked at vendor capabilities regarding other sign features. The results show that, vendors can accurately locate the majority of signs. However, while vendors were unable to consistently capture sign, retroreflectivity readings within 10% accuracy, a comparison of MUTCD pass/fail ratings for signs for these vendors, showed that they captured ground-mounted signs with 88% and 97% accuracy, and overhead signs with 100% accuracy., Combining the sign location rates and the accuracy of the pass/fail comparison results in an overall accuracy ranging from, 63% to 70% which is comparable to the accuracy achieved by other sign management methods. Vendors also showed, some consistency in capturing the lower retroreflectivity readings, which should be more important to the NCDOT, as, MUTCD thresholds for failing signs are set at the lower level readings. Following location of the sign, vendors showed, promise collecting many of the other sign features, such as MUTCD code and roadside orientation, which showed, significant improvement from the previous study. This study shows that there is still room for improvement, but also, exhibits the improvements that vendors have already made in capturing all sign features.

98-1783, The effectiveness of sediment control devices was studied on a large NC DOT project to determine the, effects of different designs and conditions. Flow and sediment content of water exiting six different traps, and basins were measured and the amount of sediment trapped estimated from periodic surveys. Sediment, trapping and discharges strongly suggested that commonly used designs are relatively ineffective. The three, devices with rock dam outlets had sediment retention of <57% of sediment entering the traps and discharged, up to 20 t ac-1 during up to 12 months of monitoring. In contrast, the skimmer basins with surface outlets, stable sides and inlets, and porous baffles, retained more that 90% of sediment entering them, as long as they, were properly maintained. While the skimmer basins retained most of the sediment entering it, the, discharges were still relatively turbid and contained considerable suspended solids. The skimmer basin, which was monitored longest (one year) had average turbidity of 891 nephelpmetric turbidity units (NTU), and total suspended solids (TSS) of 537 mg L-1. It is likely that the remaining suspended materials are very, fine and will not settle by gravity alone under typical retention times. The more efficient designs tended to, retain more of the coarse fraction entering the basins than the less efficient designs. The improvement in, sediment retention with the design improvements will significantly reduce the impacts of land disturbances, from construction activity on water quality in nearby streams.

This project developed an analysis methodology and associated software implementation for the evaluation of, significant work zone impacts on freeways in North Carolina. The FREEVAL-WZ software tool allows the analyst, to predict the operational impacts of work zones, including impacts from capacity reductions, lane closures, reduced, speed limits and traffic diversions. The research is based on the 2010 Highway Capacity Manual Freeway Facilities, methodology and its companion FREEVAL-2010 computational engine. Through this project, the tool was, enhanced to allow for work-zone specific impact assessment, customized to the needs of the NCDOT Traffic, Management Unit. The tool includes a new planning-level feature that enables a quick assessment of work zone, impacts, while still allowing for a more detailed operational analysis. The tool uses default values for work zone, inputs specific for North Carolina conditions. However, all inputs can be adjusted by the user. Further, the, methodology allows the analyst to calculate user cost impacts of the work zone. All calculations and algorithms in, FREEVAL-WZ are consistent with the methodologies in the 2010 Highway Capacity Manual. The project included, a significant field validation and model calibration efforts with operational data collected directly by NCDOT using, field sensors. The data was used to compare predicted model performance to field operations and to develop default, parameters for typical North Carolina work zone configurations. Project deliverables include a final report, the, actual FREEVAL-WZ tool, and a software user manual.

Accurate predictions of camber and prestress losses for prestressed concrete bridge girders are essential to minimizing the frequency and cost of construction problems. The time-dependent nature of prestress losses, variable concrete properties, and problems related to production variables make it difficult to predict camber accurately. The recent problems experienced by NCDOT during construction are mainly related to inaccurate prediction of camber. In this report, several factors related to girder production are shown to have a significant impact on the prediction of camber. A detailed method and an approximate method for predicting camber that both utilize adjustments to account for the production factors are proposed. The detailed method uses time-dependent losses calculations and creep factors to predict camber, while the approximate method uses multipliers. The current NCDOT method and the proposed methods are analyzed and compared using an extensive database of field measurements. The proposed methods are shown to provide significant improvements to the camber predictions in comparison to the current NCDOT method. Recommendations for design and production practices are provided.

In this study, an attempt was made to determine the effect of prolonged heating on the bond strength between, aggregate and asphalt that contained anti-strip additives (LOF 6500 and Morelife 2200). On account of the, substantial decrease of anti-strip additive contents for both asphalt binders and mixes when subjected to prolonged, heating, whether the loss of additive content due to storage and transport at elevated temperatures affects mix, performance in terms of moisture sensitivity or not, was evaluated in this study. A series of tests, namely Tensile, Strength Ratio Test (TSR), Contact Angle test, Pneumatic Adhesion test and Atomic Force Microscopy (AFM) test, were performed, and the results obtained from each of these tests were compared to come to a reliable conclusion, regarding effectiveness of the various tests for assessing the effect of prolonged heating on the adhesive bond, strength. Results obtained from the Tensile Strength Ratio test clearly show that as the prolonged heating duration, increased the TSR values failed the limiting value of 85% as followed by NCDOT specification in as little as six, hours and continued to further decrease with heating duration., Tests were also conducted on asphalt cement containing LOF 6500 antistrip additive using the contact angle, goniometer, PATTI device and atomic force microscopy (AFM). The results obtained in this study were, inconclusive for the above mentioned three devices.

Horizontal curves are relatively dangerous features, with collision rates at least 1.5 times that of comparable tangent, sections on average. To help make these segments safer, this research developed consistent study methods with, which field personnel could examine curves. This research included an examination of curve crash characteristics, the development of a manual field investigation procedure, the development of calibration factors for the relevant, collision prediction equations in Highway Safety Manual, and GIS methods for finding key curve parameters., Based on this work, the research team recommends a systematic approach for identifying, investigating, analyzing, and evaluating horizontal curves. This systematic approach can lead to the selection and evaluation of promising, curves, assessment of funding sources, and a recommendation of appropriate countermeasures. The approach, should sometimes include a statistical analysis of horizontal curve collisions taking into account various road, crash, weather, and temporal attributes to help identify any unique circumstances that create an overrepresentation of, certain types or characteristics of collisions. The research team found a calibration factor of 1.33 for the collision, prediction equation for two-lane roads in the Highway Safety Manual. The research team also recommends several, methodologies to identify and measure the key characteristics of horizontal curves using data already stored in GIS, files.

This study investigated the effect of moisture and amount of baghouse fines on AC mixes. Two, types of baghouse fines, each with a different gradation, were used in varying concentrations to prepare, laboratory samples. The binder used was PG64-22 and the anti-strip additive used was LOF 6500., TSR (AASHTO T283) test results showed a reduction in retained strength for specimens without, additive as compared to the specimens containing additive showing the effectiveness of the additive in, preventing the moisture damage. Mixes with highest amount of baghouse fines showed resistance to, moisture damage in presence of the anti-strip additive. However, absence of additive reduced the strength, ratio considerably to the point that these mixes would be unacceptable under current NCDOT criterion., The mix performance was evaluated using the SST machine to determine the rutting and fatigue, characteristics of the mixes. In general, it was observed that moisture conditioning reduced rutting and, fatigue resistance of the mixes considerably, although, the TSR test result showed that an LOF-6500 antistrip, dosage of 0.5% was sufficient to reduce moisture damage to the point that the mixes would be, acceptable under the current NCDOT criterion of 85% retained strength.

"The objective of this effort is to develop safety performance functions (SPFs) for different types of facilities in North Carolina, and illustrate how they can be used to improve the decision making process. The prediction models in Part C of the Highway, Safety Manual were calibrated using data from North Carolina. SPFs were estimated for 9 crash types for 16 roadway types, using statewide data from North Carolina – these SPFs just include AADT and can be used for network screening. In addition, SPFs for rural two lane roads were developed using AADT and other site characteristics including shoulder width/type and, terrain. Using examples, this report outlines how the different SPFs can be used for network screening, project level analysis, and before-after evaluation using the empirical Bayes method. Finally, there is a discussion of how NCDOT can use the SPFs in, the future by either calibrating the SPFs developed in this effort and/or develop SPFs using negative binomial regression. Along, with the final report are Excel files that can be used by NCDOT to calibrate the SPFs in the future and to implement the HSM, prediction methodology."

The intent of this study was to provide information necessary to characterize the present concentrations of an emerging transportation related contaminant, the platinum group metals (PGM), and to provide background information necessary to explore the potential uses of these metals as a specific marker of transportation related contamination that results from the discharge of road runoff into streams. Thirty-seven road crossings were evaluated in the Atlantic Slope of central North Carolina. Mussel tissue and sediment samples were collected from upstream and downstream of each road crossing. Samples were analyzed for the platinum group metal platinum (Pt), as well two other common transportation pollutants, lead and cadmium, and a common atmospheric pollutant, mercury. The enrichment of pollutants (downstream concentration -- upstream concentration) was compared to the number of vehicles crossing the stream. Local stream environmental variables and landscape scale variables were used to model the concentration of Pt in mussel tissue. Two 28-day laboratory toxicity tests, one with Pt and one with Pb, were conducted to assess the potential threat that current concentrations of these metals pose to native mussel fauna. The correlation of enrichment of the metals at bridge sites was weak for all metals studied. We hypothesize that complex hydrologic alteration caused by highway crossing structures was responsible for increased variation in downstream samples. Multiple samples taken from a single stream over an 8 km stream reach indicated that Pt concentrations in mussel tissue and sediment was enriched downstream of a road crossing, but the enrichment was not uniform and enrichment does not peak for several km downstream from the source. Results from the 28-day tests indicated that PGM may not pose an immediate threat to adult mussels and that mussels are a good sentinel species for studying PGM.

2014-13, This research effort examined the corridor impacts of various signal timing and geometric strategies to improve the, operational challenges observed at DDIs. A microsimulation analysis was conducted using a calibrated and validated DDI, modeled after the National Avenue and US-60 interchange in Springfield, Missouri. Four heavy volume scenarios were, tested in combination with seven categories of strategies. These strategies were selected from a larger pool of strategies, under the guidance of the NCDOT research panel and national expert recommendations. In addition to the microsimulation, effort, a cost analysis was conducted for the same strategies. Considerations were made for implementation cost, disruption, to user during implementation, and crash modification impacts. Finally, three sites in North Carolina were selected for field, study. In the microsimulation analysis, those strategies which reduced the number of phases at the downstream adjacent, intersection had the greatest benefit on the corridor routes for all four heavy volume scenarios. The reduction in phases, reduced loss time and increased capacity for the intersection. Unfortunately, these strategies were also the most expensive, alternatives studied, were likely to be the most disruptive to users during implementation.

NCDOT Project 2014-11, The methodology provided in this report provides guidance for NCDOT conversions of two‐way, stop controlled intersections to other intersection types to enhance the effective allocation of, public funds. The findings of this project have been incorporated into the study’s primary, deliverable, the spreadsheet‐based NCDOT Intersection Life Cycle Cost Comparison Tool, which, combines enhanced HCM 2010 methodologies and standard cost benefit analysis methodologies, to calculate the long‐term net benefits of converting a two‐way stop controlled intersections to, three different intersection options: 1) all‐ way stop controlled, 2) signalized, and 3) roundabout, types. This deliverable is designed for use during the planning phase of potential intersection, conversion projects to help stakeholders identify the most cost‐effective conversion, configuration option. This report summarizes the findings of all project tasks.

NCDOT Project 2013¿09, This is the final project report of NCDOT research project 2013‐09: Delay and User Cost Estimation for Work Zones, on Urban Arterials. The project seeked to develop a methodology for quantifying delay and user cost impacts of, arterial work zones in North Carolina in an analytical framework, supported by NC‐specific empirical performance, data of arterial work zones. NCDOT recently acquired a similar methodology for the evaluation of significant work, zones on freeways, and this research aims to build on that prior effort to develop a companion tool for arterial, streets. Just as with the prior effort (NCDOT Research Project 2010‐08), the methodology developed in this project, would be implemented in a software tool, ARTVAL‐WZ, which can be used directly for in‐house analyses of these, types of work zones to assure seamless technology transfer of these research products. This report summarizes the, findings of all project tasks.

This project completed the North Carolina portion of the pooled fund Southeast Fatal Analysis Project. In addition, to completing this portion of the causal chain analysis for NC Crashes, the project developed a ranked, comprehensive list of candidate safety countermeasures likely to be effective for reducing both the number and, severity of fatal crashes on two-lane rural roads in North Carolina. This list includes countermeasures ranked, according to their expected influence on fatal crash frequency and severity for two-lane rural roads.

The North Carolina Department of Transportation (NCDOT) is progressing toward developing quantitative and systematic, criteria that address the implementation of undercutting as a subgrade stabilization measure. As part of this effort, a, laboratory study and numerical analysis were performed from 2008 to 2010 with the results providing proposed criteria for, undercutting under various roadway site conditions and the adequacy of stabilization measures typically employed if, undercut was deemed necessary. These criteria provide provisions for discerning possible rutting and pumping of the, subgrade under construction loading, and provide response and subgrade stiffness under repeated loading of 10,000 cycles., The work in this report is focused on performing full-scale testing in the field on instrumented unpaved roadway sections to, collect data for the validation of guidelines developed from the laboratory and modeling study. Four 16 feet wide by 50 feet, long stabilized test sections were built on poor subgrade soils encountered in the Coastal Plain region of North Carolina., One test section encompassed undercutting and replacement with select material (Class II), the second and third test sections, included reinforcement using a geogrid and geotextile, respectively, in conjunction with undercutting and replacement with, ABC (Class IV), and a fourth test section included cement treatment of the soft subgrade soil. Full-scale testing was, conducted on the test pad by applying 1000 consecutive truck passes using a fully loaded tandem-axle dump truck over a, period of four days. During this time visual observations were noted and measurements were collected regarding rut depth, vertical stress increase at the base/subgrade interface, and subgrade moisture content with truck passes. Once trafficking, was completed, the test pad was re-graded and proof roll testing was performed to look for signs of pumping and rutting., Based on the field results, the proposed undercut criteria are evaluated in regards to the ability to discern the need for, undercutting as well as predict the performance of the stabilized test sections. Finally, a performance cost analysis is, conducted to illustrate the relative cost of each stabilization measure in relation to the measured performance (rutting) such, that an informed decision on cost-effective subgrade stabilization can be made.

An efficient and accurate inventory of a state highway agency’s assets, along with the means to assess the condition, of those assets and model their performance, is critical to enabling an agency to make informed investment decisions, in a Transportation Asset Management (TAM) environment. Today, new technologies provide fast and improved, ways to gather, process, and analyze data. The key is to identify and gather the most useful, reliable, cost-effect, information and use it to make informed decisions for asset management., Four key infrastructure areas have been identified as primary asset components; pavements, bridges, geotechnical, features, and roadside appurtenances. Each area contains multiple categories and data elements important for sound, decision making. Although some similarities exist in these four primary categories, the nature of data collection may, differ, depending on the asset type. The, sheer number of data elements and the length of asset networks for, pavements and roadside appurtenances render the automated highway speed data collection method a necessity, rather than a luxury. However, the discrete nature of bridges and geotechnical features make the automated mobile, data collection method on a network level unfeasible with today’s technology., Important issues in the collection process include precision, subjectivity and variability of the process itself, as well, as speed, safety of the survey crew, proximity of the public, cost, etc. Although previous research has attempted to, address these issues and determine the most appropriate method(s), the question remains as to which roadway data, collection system is best for state highway agencies given real world constraints. This research set up a “sealed, envelope” experiment wherein the identification, location, description, and quality of the asset data elements are, known only to NCSU researchers. Vendors are informed of only the data necessary to perform their evaluation. To, support this effort at 95-mile test course near Raleigh, North Carolina was identified, which contained a sampling of, pavement, roadside, geotechnical and bridge elements. This document reports on the findings from the study.

Field data for in-use fuel consumption and emission rates were collected for 15 nonroad vehicles using a portable emission, measurement system (PEMS). Each vehicle, including 5 backhoes, 4 front end loaders, and 6 motor graders, were tested, once on petroleum diesel and once on B20 biodiesel. The vehicles included different model years and thus represent a, variety of engine certification tiers. A methodology was developed for study design, field data collection, data screening and, quality assurance, data analysis, and benchmarking of the data. The average rate of loss of data due to data quality issues was, 6.9%. On average, over 3 hours of valid data were collected in each test. Time-based emission factors were found to, increase monotonically with respect to engine manifold absolute pressure. Fuel-based emission factors were mainly sensitive, to differences between idle and non-idle engine operation. Typical duty cycles were quantified in terms of frequency, distributions of manifold absolute pressure (MAP) and used to estimate cycle average emission factors. On average, the use, of B20 instead of petroleum diesel lead to an insignificant 1.8% decrease in NO emission rate and significant decreases of 18, 26, and 25% for opacity, HC, and CO, respectively. Emission rates were also found to decrease significantly when, comparing newer, higher tier vehicles to lower ones. Fuel use rate, and NO, HC, and CO emission factors, were found to be, of similar magnitude as independent benchmark data. An emissions inventory was developed for these vehicles. The current, fuel mix of B20 and petroleum diesel is estimated to produce 0.4 to 6.4 percent lower emissions, depending on the pollutant, than usage of 100 percent petroleum diesel. If NCDOT were to use 100% B20 in the same vehicles, then additional, reductions in emissions of each pollutant would be approximately 2.0% to 36.9% lower than for the current fuel mix of B20, and petroleum diesel. Although higher tier engines have lower emissions factors for each pollutant than lower tier engines, their annual average emissions tend to be higher because of greater utilization. Specific recommendations are made for, future work, including expansion of the use of B20 to further reduce tailpipe emissions in the NCDOT inventory, replacement of older vehicles with newer ones, field data for larger sample sizes of vehicles for each Tier in order to improve, confidence in the emissions factors and inventories, assessment of Tier 4 vehicles as they become available using improved, instrumentation, evaluation of fuel formulations, evaluations of other vehicle types, and others.

The present project had two main objectives, to experimentally and analytically investigate a bridge deck reinforced with glass, fiber reinforced polymer rebars, and to perform durability tests on four rebar types., An analytical investigation was performed using the finite element software ANSYS for both the actual bridge deck, and for the, reduced size laboratory experiment. In addition, laboratory experiments were also performed on an 11 ft long bridge deck model, built inside the structures lab. Except for the length of the girder-deck model, the true scale was used for every other dimension., Three different tests were performed on the model, and the test data verified the analytical results. Once completed, this bridge, located in Macon County was instrumented and tested using two loaded tandem trucks., For the durability testing, four different types of Glass Fiber Reinforced Polymer (GFRP) reinforcement provided by different, rebar vendors were evaluated under exposure to an alkaline environment at different temperatures. For the moisture tests, a total, of 96 specimens were monitored for changes in length, diameter, and weight. A total 128 unscathed samples and 64 “nicked”, samples – simulating defects to the rebars that might occur on the field site – were tested in tension to determine the rate of, degradation in tensile properties. Concrete cylinders were poured, and 168 pullout specimens were tested (84 at 5Øb and 84 at, 8Øb).

This project involved four distinct research activities, (1) the influence of temperature on lime-stabilized soils, (2) the influence of temperature on cement-stabilized soils (3) temperature modeling of stabilized subgrade and (4) use of calcium chloride to accelerate strength gain of cement-stabilized soils., Significant conclusions from the lime-focused research include that the minimum lime content of a soil increases as temperature decreases. Increased curing duration leads to decreases in pore fluid pH. However, this reduction in pH is less at lower temperatures, indicating that little reactivity occurs below 50°F. Exposure to freeze-thaw cycles or initial curing at 35°F resulted in significant reductions in strength gain for a given curing duration. However, once the freeze-thaw cycles or temperature reduction was removed, strength gain resumed at approximately the same rate. Overall, these results suggest that current specifications may be modified to allow lime stabilization to proceed in cooler temperatures, provided a corresponding increase in curing time and/or thermal protection is provided prior to loading., The soil cement data indicate that curing soil-cement at lower temperatures will result in lower strengths. For example, the 7 day strength for samples cured at 25oF was less than the strength of samples cured at 50oF or 70oF by a factor ranging from 2-6. Likewise, the 7 day strength for samples cured at 35oF was less than the strength of samples cured at 50oF or 70oF by approximately 20-25%. Additionally, on the basis of 15 repeat tests for 3 and 7 day curing periods, for three different soils, results indicate that the mean strength at 3 days is 84-93% of that for 7 days, in support of a potential change in current subgrade evaluation practice predicated on the longer duration., Specifications for stabilization work have often been based on air temperature measurements, however the performance of lime or cement treated soil is expected to be more closely related to the in situ temperature. This research has found that the thermal diffusivity of both lime and cement-stabilized subgrades varies from 3.8 x 10-7 m2/s (2.14 in2/hr) to 9.8 x 10-7 m2/s (5.46 in2/hr). These data were incorporated into a model that relates air and soil temperatures. A computer application was developed to use the model to make predictions of subgrade temperatures and cured strength., A window of efficacy was observed for Buncombe, Guilford and Johnston county soil cement mixes, with ideal ranges at 50oF curing conditions of 0.25% – 1.0%, 0.25%-0.75% and 1.25%-1.75%, respectively (percentages reflect mass of CaCl2 per mass of cement). However these optimum ranges vanished or changed to levels untested at 35oF curing conditions. A field trial was conducted with CaCl2 doses of 2.3% and 8.3%, and both of these dosage levels resulted in weakening of the material, as evaluated by in situ dynamic cone penetration tests and unconfined compression testing of field-mixed samples. Laboratory mixed samples of the same material resulted in strength increases. CaCl2 modification increases the electrical conductivity and dielectric value of soil-cement mixtures which might imply increased susceptibility to longer term moisture-induced weakening at high dosage levels. The cost of CaCl2 modification at effective doses is likely to be less than 10% of cement costs. The overall body of research presented in this report suggests that CaCl2 modification of soil-cement is not a mature enough approach to serve as a method for mitigating the effects of low temperatures on strength gain. Additional data are required to probe the sensitivity of temperature, mixing method and soil type.

This research report is geared at providing guidance to NCDOT for when to consider marking crosswalks at, uncontrolled approaches for pedestrians, installing pedestrian signal heads at existing signalized intersections, or, providing supplemental treatments at a crossing location., The primary deliverable of the project, the crosswalk assessment flowchart, is intended to be a self-contained, wall-mounted, poster that fully describes most aspects of the evaluation and decision-making process. This report is intended, to supplement that flowchart, providing background for the flowchart with references to research and underlying data, used to develop the guidance., The guidelines principally consist of four parts: Step 1) Document Existing Characteristics / Signalized Crossing, Assessment, Step 2) Unsignalized Crossing or Midblock Crossing Assessment, Step 3) Additional / Alternative, Treatments Assessment, and Step 4) Pedestrian Hybrid Beacon (PHB) Assessment.

NCDOT/NC/2012-0731, This study details the research team’s approach and findings for mapping transportation-disadvantaged, populations and holding interviews with local practitioners and vulnerable groups The study provides a, straightforward and practice-ready outreach process that can be used by transportation practitioners to, better address the needs of populations facing significant mobility challenges. Underserved groups in six, North Carolina counties (Beaufort, Chatham, Graham, Wake, Warren, Wilson) are identified and mapped, with GIS applications. Most often those protected under Title VI requirements – low-income and minority, populations – but also the elderly, disabled, children, and those with language barriers have mobility, needs that are often unmet., Interview findings demonstrated that policy provisions, such as restrictive eligibility requirements for, paratransit, prohibitive monetary and time costs, and insufficient public transportation offerings, among, other reasons, pointed to why certain groups suffer transportation disadvantage., This study also provides transportation practitioners with a step-by-step process to identify and map, transportation-disadvantage populations in a user-friendly Practitioner Guide. The guide serves as a, companion to the research and is included in the appendix of this report.

Experiences and results of research by the North Carolina Central University Department of Public Administration while a, conducting feasibility study for establishing a new multidisciplinary undergraduate degree in public transportation administration, and management are shared. Multiple research methods yielded information about the perspectives of employees in managerial, supervisory and non-supervisory occupations in the North Carolina public transportation industry., Methods used included a literature review of education and curriculum planning for transportation degrees at public colleges and, universities; focus groups (qualitative research) to acquire an understanding and perspectives of employees and stakeholders in, the public transportation industry for establishing a degree; interviews and surveys of directors of North Carolina public, universities and select University Transportation Centers, Some of the key findings include overwhelming support for establishing a new four-year degree at a public North Carolina, University. Public transportation employees described the conditions and support they would need to enroll in a four-year, program. Managers and supervisors described the kinds of support they would be willing to give to employees enrolled in a fouryear, program. Other interest expressed for certification or short-courses, online courses, and availability of courses within 30, miles of employee’s residence.

2009 - 09, This report summarizes traffic operational evaluation of six select traffic impact analysis (TIA) case sites and the effectiveness of forecasting methods used in TIA studies. Six TIA case sites comprising 15 signalized intersections and 2 unsignalized intersections in North Carolina (four sites in the Charlotte region and two sites in the Raleigh region) were considered for comparison. Data collected during morning peak hours (7 AM – 9 AM) and evening peak hours (4 PM – 6 PM) on a typical weekday were used for evaluation. The measures of effectiveness (MOEs) considered for the evaluation of data are total number of hourly stops, 50th percentile queue length, average intersection delay, and level-of-service (LOS)., The comparison of operational performance and forecasting methods was conducted using three different methods. The first method was used to compare the operational performance at selected intersections before and after the construction of the new development proposed in the TIA study using Synchro® traffic simulation software. The second method was used to compare “what was forecasted to happen after the development?” with “what is happening after the development?” using Synchro® traffic simulation software. The third method was used to compare outcomes obtained using Synchro® traffic simulation software with field observations after the development., Results obtained from the evaluations indicate that new developments naturally have a considerable effect on operational performance at intersections near the development. The build-out year forecasted traffic volumes and traffic conditions had not been reached for the six reviewed TIA reports. This difference can at least in part be attributed to economic conditions and the fact that several of the site‟s still had vacant parcels / outlots and additional unconstructed development. Recognizing that seasonal traffic fluctuations can have a significant impact on the magnitude of commercial site traffic, improved forecasts and traffic operational condition modeling could be achieved with improved regional traffic growth rates, conservative peak hour factors (PHF) and use of representative heavy vehicle percentages. Given the variability and significance of the build out of complex mixed use sites a five year build out horizon may be more appropriate for determination of needed improvements and acceptable levels of service since a three year window often only allows completion of the construction of the primary anchors.

DTMC75-07-D-0006, The researchers conducted a study of the springtime ecology of an isolated North Carolina-Tennessee population of the Virginia big-eared bat (Corynorhinus townsendii virginianus), a federally endangered species. With limited data on the whereabouts of this population during the maternity season, the researchers could not adequately predict the impacts of transportation improvement projects (TIPs) such as the proposed widening of NC 105 (R-2566), which is ~3.3 km from the population's hibernacula on Grandfather Mountain, NC. The three objectives of the study were: 1) document seasonal movements and assess foraging habitat selection, 2) locate and describe springtime roosts and assess landscape-scale selection of roosting habitat, and 3) describe winter bat activity at the population's main hibernaculum. The researchers radio-tagged 44 adult bats (42 female, 2 male), located 35 roost sites (25 rock and 10 building roosts), and delineated foraging home range polygons for 10 bats. The researchers found the first known maternity roost sites for this species in NC, including a primary maternity roost on private land 14.4 km north-northwest from the hibernacula (≥ 359 bats used this roost), and the researchers found the first known roosts for Tennessee. Bats moved across NC 105, NC 194, and other roads while commuting the short distance to the primary maternity roost, but generally did not cross major roads during nighttime foraging bouts. Bats moved relatively short distances between the hibernacula and springtime roost sites (0.1-24.1 km), but covered a relatively large area while foraging (~330 ha on average) mainly over forested lands. Most bats used a primary maternity roost and ≥ 1 secondary roosts; primary roosts were larger, with cooler and more stable temperatures. The researchers detected winter bat activity at the hibernaculum, even on very cold days, and suggest further surveys to monitor the hibernating population. It is essential that the NC population of Vir, This report's appendices are included with the report as a separate file.

"Field, greenhouse, and laboratory studies were conducted to evaluate the feasibility for the use of native warm season grasses (NWSGs) on North Carolina roadsides. Location, equipment, and multiple grass species were assessed to determine the ideal method and timing as well as specific herbicide regimes. Few differences were present between planting equipment used, but planting date was extremely important. Stand establishment was very sensitive to environmental conditions and establishment often took two or more years. Thus, individual construction projects should be critically evaluated for NWSG planting depending upon whether ideal establishment conditions will be present., Studies were also initiated to assess the best means of control for alligatorweed and Japanese knotweed, two invasive and problematic species among North Carolina roadsides and right-of-ways. At 7 MAT, Japanese knotweed control with glyphosate, imazapyr, glyphosate plus imazamox, and glyphosate plus imazapyr was at least 93%. Glyposate plus penoxsulam controlled the plant 75%. Treatments that did not include imazapyr or glyphosate did not exceed 20% control., Imazapyr provided excellent control of alligatorweed in almost every trial conducted. No other active ingredient evaluated was as consistent as imazapyr."

Research in this report presents the first study documented in literature to characterize, the surface disturbance and associated ecological impact due to pile jetting process. The enclosed, work describes development of phenomenological pile jetting model in various soil profiles, through implementation of a laboratory experimental program, field testing program, and, comprehensive data analyses. The physical phenomenon of jetting was observed in the, laboratory and a model for computing disturbance created by jetted-pile installations was, developed. Four test sites were chosen in different geographical locations in Eastern North, Carolina to perform a total of 26 jetted pile installations. Ecological impacts of jetting on marine, environment and tidal marches are discussed and presented.

Maintenance activities account for a substantial portion of the life cycle costs of a roadway and are categorized by means of performance: contract maintenance by outside forces or in-house maintenance by DOT personnel and equipment. The nature and timing of the in-house maintenance tasks can be planned based on currently available asset performance models, but estimating the cost of future work requires knowledge of the current maintenance costs and the trends in maintenance costs., The purpose of this research was to develop a set of maintenance cost indices that can be updated annually and used to quantify trends of in-house maintenance costs. Indices were developed for the Roadside, Maintenance, Traffic, and Bridge categories of the Standing Maintenance budget. A composite index was also developed to represent overall Roadway Maintenance. The indices were developed in a fixed base, Laspeyres index form with 2014 selected as the base period. A total of 20 maintenance tasks were selected for the basket of goods and collectively accounted for 76 percent of recorded costs in the base year. The unit cost data recorded in work order records was not normally distributed and the median value was selected for use in the calculations. The total quantity for each task was also calculated from the work order records., Work order data records from 2012 to 2015 were used to demonstrate the index calculations. A spreadsheet tool was developed to facilitate calculating and archiving index values.

The genus Alasmidonta currently contains 12 species with 3 species presumed extinct., Six species of Alasmidonta occur in North Carolina, including the presumed extinct Alasmidonta, robusta. Tissue samples from all taxa of living Alasmidonta species were included in a test of the, monophyly of the genus and the relationships of the species using mitochondrial DNA sequences, from cytochrome oxidase c subunit 1 (COI) and NADH dehydrogenase subunit (ND1)., Alasmidonta (Prolasmidonta) heterodon and Alasmidonta (Pressodonta) viridis are significantly, different from the rest of Alasmidonta and the two subgenera are elevated to generic level., Alasmidonta varicosa is split into two separate species as is A. viridis. Alasmidonta raveneliana, is represented by two separate conservation units corresponding to the French Broad and Little, Tennessee River drainages. Further work is needed to understand the variation in A. marginata, between the upper Mississippi River basin and the Ohio River drainage populations.

This project uses Roadway Reviews and Focus Groups to gain insight into how North Carolina residents assess and prioritize roadway assets. During a three-week period in November 2015, researchers from the Institute for Transportation Research and Education (ITRE) surveyed more than 350 residents in six locations across the state (Asheville, Burlington, Charlotte, Jonesville, Rocky Mount, and Wilmington) during both daytime and nighttime hours to determine expectations for the condition of NC roadways and to identify features that NC residents think are the most important on different types of roadways.

The present study used commercial motor vehicle (CMV) crash data from NCDOT’s Traffic Engineering Accident, Analysis System (TEAAS) to infer the presence and relative extent of STAA dimensioned vehicles operating, beyond the 3-mile buffer of the present STAA Truck Network in North Carolina. STAA dimensioned vehicles, include trailers 53ft or greater in length and double trailers. STAA routes in NC constitute only about 8 percent of all, state-maintained roadway miles. The data showed that approximately 87 percent of all large truck crashes took place, on STAA network roads during the period 2001-2005. While only 13 percent of large truck involved crashes took, place on roads ‘off’ the network, the likelihood of any given off-network crash involving a fatality was twice that of, a crash taking place on the network. Off network crashes involving large trucks are problematic for reasons other, than safety, especially in metropolitan areas where operations, irrespective of crash involvement, are associated with, traffic delays (due to the maneuvering/turning requirements of larger vehicles) and infrastructure damage. The report, provides GIS ‘maps’ of each of the eight NCSHP troop areas, the network and its 3-mile buffer and the location and, severity of all large truck-involved crashes reported as taking place ‘off’ the network. The report also provides a, detailed description of the attributes of off-network crashes for 2001-2005 for each NCSHP troop. Several criteria, were explored as a means for ranking troop areas in terms of need for STAA improvements. The report also, identifies specific off-network routes at the county and troop levels having the highest numbers of crashes per mile., Recommendations are provided for ‘next steps’ as well as a plan for technology transfer and implementation.

This report summarizes the finite element modeling and simulation efforts on evaluating the performance of cable median barriers including the current and several proposed retrofit designs. It also synthesizes a literature review of the performance evaluation of cable median barriers, existing finite element modeling and simulation work on roadside safety, and an analysis of crash data collected by the North Carolina Department of Transportation., Two retrofit options were proposed for this project, and several designs for each option were evaluated using the full-scale finite element simulations of a vehicle crashing into a cable median barrier. The simulation results showed that the potential of vehicle under-riding in back-side impacts was higher than that for front-side impacts, because the vehicle’s suspension was compressed and there was less median traversal width for back-side impacts. The evaluation of different retrofit options indicated that lowering the middle and bottom cables and changing the sides of all cables on the posts could increase the likelihood of redirecting small vehicles for back-side impacts without sacrificing the CMB’s performance for front-side impacts and for large vehicle impacts. For each of the two retrofit options, a new design was developed and evaluated. The simulation results showed that the newly developed three-cable and four-cable retrofit designs could improve the performance relative to the current design in back-side impacts without sacrificing its performance in front-side impacts., The simulation results of this project should only be used to investigate performance trends for evaluating the CMBs; they should not be used to draw definitive conclusions about CMB performance for a specific crash event, because many factors affecting CMB performance were not considered in the simulations. Finite element analysis was shown to be a useful tool in crash analysis and could be used in future research to investigate these remaining issues.

Stormwater runoff from roadways is a source of surface water pollution in North Carolina. The North Carolina Department of Transportation (NCDOT) is required to implement stormwater control measures (SCMs) in the linear environment. NCDOT has specific interest in evaluating pollutant loads from interstate highways and potential stormwater treatment measures. The research presented herein focuses on monitoring of highway runoff at four sites along Interstate 40 (I-40) in Johnston, Sampson, and Duplin counties. This entire stretch of I-40 had a permeable overlay [known as a permeable friction course (PFC)] applied in November, 1998. The overlay is porous, and allows water to pass through the surface of the pavement, reducing splash during rainfall and allowing for improved vehicle traction (Barrett et al. 2006). Drainage from the PFC was monitored at all four sites to determine highway pollutant concentrations and loads. Roadside filter strips are nearly ubiquitous on highways, as they are constructed to make grade and to hydraulically connect the roadway to the roadside swale. Two roadside filter strips (21.5 ft in width) were evaluated in this study. Finally, four linear roadside swales were monitored to determine their hydrologic and water quality benefits. Two of these swales were dry swales, meaning that they drained inter-event. The other two swales had wetland characteristics, including hydrophytic vegetation, hydric soils, and wetland hydrology.

Lane drops downstream of signalized intersections are found on many urban and suburban streets and highways. Since, drivers tend to avoid using the short lane due to the potential for stressful merges downstream of the signal, the short lane is, typically under-utilized. Previous research indicates that the default lane utilization factors in the Highway Capacity Manual, (HCM) appear to overestimate traffic in the short lane. The purpose of this project was to develop models to predict lane, utilization factors for six defined intersection types and to assess how a lane drop affects safety near intersections., Traffic, signal, and collision data were collected at 94 sites in North Carolina. Based on 15 candidate factors, multiple, regression models were developed for the purpose of predicting the lane utilization factor. This study found that the downstream, lane length and traffic intensity positively correlate with the lane utilization factor, and that some geometric variables at the, approach may also influence lane utilization. Collision data analysis results show that collision rates downstream of an, intersection decline as the distance to a lane drop increase. The results also show that the lane drop type does not affect collision, rates upstream and downstream of intersections., Many of the results derived from this study are consistent with previous research. The models developed should provide, designers and traffic engineers with concrete methods to improve lane utilization when lane drops are contemplated., A re-assessment of the effect of lane utilization on capacity is recommended, since models in the HCM consistently, overestimate delay for all types of lane drop intersections with low lane utilization.

In order for the Transportation Planning Board to provide oversight and assistance to the 20 RPOs in the state, they, need effective evaluation criteria and performance measures. The existing measures, including the annual, performance report, do not meet those needs. We developed measures they needed in order to fulfill their goals., We conducted an extensive review of published research and a search of RPO-related documents in each state in, order to identify evaluation and performance 'best practices' in each state. We met with the TPB, NCARPO, and, representatives of RPO constituents to determine concerns with existing measures and their needs and suggestions, for the new performance measures. After developing the evaluation criteria and performance measures, the project, team presented the plans to the various groups, and gathered feedback. The feedback was used to clarify any issues, within the new performance measures. The development of the performance measures was driven by several, principles: (1) The assessments developed, where possible, should be objective and quantifiable, (2) The evaluation, criteria and performance measures should be developed with input from all of the parties involved, (3) The, evaluation criteria and performance measures should facilitate the assessment of both short-term and long-term, goals, and (4) measures should be practical and cost-efficient to implement.

The Transportation Planning Branch (TPB) of the North Carolina Department of Transportation (NCDOT) desired a, user-friendly tool for determining highway capacity and service volumes for freeways, multilane highways, arterials, and, two-lane highways based upon the specific conditions present in North Carolina for use in planning applications. The tool, developed in this project is based upon the methodology and theory presented in the 2000 Highway Capacity Manual, with default values established specifically for North Carolina conditions across the three regions of the state. The tool, includes a unique graphical interface and plot of the measure of effectiveness against average annual daily traffic. This, tool allows for various planning scenarios to be examined in an efficient, yet accurate manner, both visually and, numerically., Additionally, a comprehensive sensitivity analysis on the input parameters was carried out. The analysis showed that, four (4) inputs had high sensitivity, eleven (11) inputs had medium sensitivity, and six (6) inputs had low sensitivity., NCDOT’s future data collection efforts can be expanded and targeted to include information on the most sensitive inputs, to enhance future planning analysis efforts by establishing documented default values on these inputs.

The North Carolina Department of Transportation operates a large and varied fleet of on-road and off-road equipment. Regular oil changes for these machines result in significant costs due to the required labor, replacement oil and filters, and disposal of used oil, as well as downtime for the machine. Provided that oil of sufficient quality can be maintained, PM costs can be reduced by extending oil drain intervals. The purpose of this research was to monitor oil quality throughout extended drain intervals to determine the type, rate, and magnitude of resulting degradation, and to investigate the potential for extending oil drain intervals. The oil analysis program established to analyze and monitor oil quality included selection of the oil analysis equipment, identification of threshold values for oil quality parameters, selection of NCDOT equipment for the program, and establishing oil sampling protocols. The OSA4 TruckCheck benchtop oil analyzer was used to analyze the physical and chemical properties of fresh and used oil samples of HD Fleet Supreme 15W-40 conventional oil and Rotella T6 5W-40 synthetic oil. Threshold values for measured oil quality parameters were established at conservative levels based on OEM recommendations, review of literature, and expert opinions., A total of 952 samples of used oil were collected and analyzed from 47 machines that consisted of trucks in classes 0209 and 0210, and tractors in classes 0303 and 0311. Trucks in classes 0209 and 0210 were sampled at approximately 1500, 2500, and 5000 miles after the oil drain, while tractors in classes 0303 and 0311 were sampled at approximately 50 hour intervals. Machines on the extended program were sampled approximately every 1,500 miles or 50 hours beyond the normally scheduled oil drain. Analyses of the used oil sampled from the NCDOT equipment showed that the oils degraded chemically as the oil aged, but the observed viscosity degradation was not related to oil age. Contamination of the oil by water, coolant, dirt, or wear metals was not generally present. The results indicate that the oil drain intervals for most of the studied equipment can be conservatively extended. The economic and environmental impact of extending oil drain intervals for similar machines in the NCDOT fleet were estimated to be annual savings of over $120,000 and 2,500 gallons of used oil.