bluuebunny/crossref_metadata_2025 huggingface dataset:
Analytical Tool for Evaluating Adaptation of a High-Occupancy Vehicle Lane to a High-Occupancy Toll Lane
Authors: Eisele William L. , Burris Mark W. , Wilner Hannah T. , Bolin Michael J.
Published: May 2018

The Texas Department of Transportation (TxDOT) sponsored research to develop a decision support tool to aid in evaluating key issues related to adapting a high-occupancy vehicle (HOV) lane to a high-occupancy toll (HOT) lane. The tool includes three broad categories of factors to consider: facility considerations, performance considerations, and institutional considerations. Facility considerations, such as design, operations, and enforcement, which have been shown to be critical factors, can present insurmountable obstacles to the implementation of HOT lanes. Performance considerations and goals allow the user to estimate the likely levels of usage and person movement, factors that always bear significantly on HOT lane development decisions. Institutional considerations are also addressed, as factors of interagency cooperation and legal limitations are historically important for HOV lane and HOT lane decisions. Finally, the research incorporates simple trade-off tools to allow TxDOT and local entities to assemble all relevant factors into an analysis to aid decision makers in evaluating the available options. The analysis tool was developed in Visual Basic.net . The program is called the High-Occupancy Toll STrategic Analysis Rating Tool (HOT START), and it is designed to be tailored easily to local needs. An application of the tool to the I-10 (Katy Freeway) in Houston is also provided. Many state departments of transportation are facing the difficult task of performing assessments of potentially adapting HOV lanes to HOT lanes, and this paper describes a practical tool that can assist such analysis.
Value Pricing Education and Outreach Model
Authors: Buckeye Kenneth R. , Munnich Lee W.
Published: May 2018

After a decade of public discussion and political debate, the I-394 MnPASS Express Lane, Minnesota's first high-occupancy toll lane, opened in May 2005. The MnPASS project was designed to improve the efficiency of I-394 by increasing the person- and vehicle-carrying capabilities of existing high-occupancy vehicle lanes, maintaining free-flow speeds for transit and carpools, and using electronic toll collection (tags/transponders and readers) for dynamic pricing and electronic enforcement. While previous road pricing initiatives in Minnesota, as in other states, have provided opportunity for public feedback, the process tends to be confrontational and less than satisfying for all parties. Both citizens and politicians often believe comments and concerns are minimized and rarely taken seriously enough to alter project plans. The I-394 Express Lane Community Task Force, however, was formed to help citizens and stakeholders fully understand the project and its goals and to provide a more effective vehicle to give advice and guidance during the development of the project. Through this process, the task force members became an informed voice for the project and an essential part of an extensive education, outreach, and public involvement process that has been critical to the success of the I-394 MnPASS project. If proved successful in the long run, this task force model increases the likelihood that Minnesota citizens will support such projects in the future.
Gaining Public Support for Congestion Charging
Authors: Gaunt Martin , Rye Tom , Ison Stephen
Published: May 2018

Until February 25, 2005, the City of Edinburgh in Scotland, United Kingdom, had advanced plans for a congestion charging scheme. However, these plans were abandoned because of public acceptability problems and in particular to a referendum on the issue. The origins of the scheme in transport plans for the Edinburgh region since 1992 are explained; the nature of the planned scheme, its extent, charging technology, and predicted effect are outlined. Some evidence is presented on how and why people voted as they did in the referendum, including their attitudes to and understanding of the proposed scheme and its promoters. From these two perspectives, it is then postulated how the scheme could have been made more acceptable.
So you want to Make a High-Occupancy Toll Lane?
Authors: Ungemah David , Swisher Myron
Published: May 2018

Although high-occupancy toll (HOT) lanes have been studied or have existed for more than 10 years, the continuing developmental nature of these concepts means that there is little guidance for project managers on how to manage the process of converting a high-occupancy vehicle (HOV) lane to a HOT lane. Many guidelines have been published about the technical elements of HOT lane development and operations. A project manager of an HOV to HOT lane conversion process would face issues that differ from those of the typical highway construction project, and managing these issues can be difficult and arduous. The intent of this paper is to address issues from the perspective of the implementing agency's project manager. Eight specific issues to be addressed within the conceptual development of the HOT lane conversion process are identified here: (a) presence of significant and predictable excess capacity in the HOV lanes, (b) presence of significant and recurring congestion in the adjacent general purpose lanes, (c) nature of traffic separation on the HOV lanes, (d) primary means of funding for the HOV lanes, (e) identification of the HOT lane program's primary objective, (f) determination of the appropriate implementing agency, (g) avoidance of overwhelming public opposition, and (h) ability to build political support for the process. This paper has summarized the first of what the authors see as four steps to the successful conversion of an HOV lane to a HOT lane: conceptual development. Planned subsequent papers will address the remaining three steps: program design, implementation, and ongoing operations.
Potential Single-Occupancy Vehicle Demand for High-Occupancy Vehicle Lanes
Authors: Burris Mark W. , Xu Lei
Published: May 2018

In recent years, there has been a growing interest in the use of high-occupancy toll (HOT) lanes as an alternative to high-occupancy vehicle (HOV) lanes to help manage the increasing demand for travel. HOT lanes combine pricing and vehicle occupancy restrictions to optimize the demand for HOV lanes. As two of the five HOT lanes in the world, the HOT lane facilities in Houston, Texas, require peak period travelers in vehicles with two occupants to pay a toll to use the lanes. During other periods of the day, two-occupant vehicles can use the lanes for free. Single-occupancy vehicles (SOVs) are never allowed. There was an opportunity to increase the usage of these HOT lanes by allowing SOV travelers to use the lanes during the off-peak periods, for an appropriate toll. This research examined the potential SOV demand for HOV lane use during the off-peak periods from the Katy Freeway and Northwest Freeway general purpose lane travelers. Of course, allowing SOVs on the HOV lanes is a multifaceted policy decision that has not been tackled by the operating agencies, and this research simply estimates the demand if such an option existed. This included estimating two important factors that influenced travelers’ potential use of the HOV lanes: their value of travel time savings (VTTS) and their value of penalty for changing their travel schedule (VPCS). It was found that respondents had VTTS approximately 45% of their hourly wage rate and VPCS approximately 3% of their hourly wage rate. Combining this information with current travel time savings and available capacity on the HOV lanes, it was found that approximately 2,000 SOV travelers per day would pay a combined total of $4,500 to use the HOV lanes during the off-peak periods.
Malaysian Toll Road Public–Private Partnership Program
Authors: Ward John L. , Sussman Joseph M.
Published: May 2018

Malaysia has relied on toll road public–private partnerships (PPPs) for more than 20 years to provide highway infrastructure. The program has been active; nearly 1,800 km of toll roads have been constructed or concession agreements have been signed for their construction. The public has been less supportive of the program due to low transparency and little public involvement. Public protests are common and may lead to long-term program instability. The complex, large-scale, interconnected, open, and sociotechnical process, developed at the Massachusetts Institute of Technology, is applied to Malaysia's toll road PPP program to develop policies that can better meet these public concerns while maintaining the financial viability of the sector. With greater transparency and public involvement, the program's political risks should be reduced and long-term stability for the government and concessionaires improved. Malaysian toll road PPPs currently are handled at the national level. However, it is argued that the focus should be at the regional transportation planning level, at which toll road PPPs can be compared with alternatives for meeting transportation needs.
Cost–Benefit Analysis of Investment in High-Speed Train System in Spain
Authors: Carrera-Gómez Gema , Castanedo-Galán Juan , Coto-Millán Pablo , Inglada Vicente , Pesquera Miguel Angel
Published: May 2018

This study compares the results of two political approaches to transport directed at the reduction of negative external effects. The comparison is between a policy of building a high-speed rail line to attract travelers away from highways and full social-cost pricing on all modes, that is, removing the implicit subsidies to all modes by pricing congestion and external costs. The former approach was adopted in 1992 in Spain with the introduction of the high-speed train in the Madrid–Seville corridor, bringing with it an important increase in the modal share of railway transport. From the analysis made, it can be concluded that from the point of view of economic efficiency and social benefit optimization, the high-speed train should not have been implemented that year (1992) in the Madrid–Seville corridor. Other transport policy approaches, such as the introduction of an optimal modal price based on the respective marginal social costs, would have increased social benefit. Therefore, the results obtained in this investigation indicate the necessity to introduce higher economic efficiency in the transport market through the application to each mode of transport of a price based on the marginal social cost.
Assessing Economic Impacts of Large-Scale Transport Infrastructure Projects
Authors: Schade Wolfgang
Published: May 2018

Assessment of large-scale transport infrastructure projects by a classical four-stage transport network model is meant to capture only the direct benefits of transport policies, while the additional indirect economic effects in nontransport markets would be partially neglected. The intent of this paper is to apply an integrated economy–transport–environment assessment model focusing on the assessment of economic impacts of national or supranational transport policies to the question of the size of indirect economic impacts of a single large-scale project. Such a model makes it possible to consider the interaction between transport and the economy as well as between the economy and transport, closing the transport–economy feedback loop. For this purpose, the European assessment of transport strategies (ASTRA) model is refined to model the implementation of the planned high-speed railway link on the Lyon–Turin corridor. This line forms part of the Trans-European Transport Networks. The estimated cost of the 257 km of new tracks is €13 billion over 10 years, which would be a sufficient size to make it a large-scale project. The results of the analysis indicate the feasibility of applying the ASTRA model for such a project assessment. Economic impacts on the country level can be detected as well as impacts for the 15 Western European Union countries, although the latter are rather small if they are measured as percentage changes to a reference scenario. A crucial task remains the analysis of impact chains that have caused and explain the model results.
Behavioral Responses to Road Pricing
Authors: Ubbels Barry , Verhoef Erik
Published: May 2018

For the evaluation and design of transport pricing strategies, it is important to have insight into the behavioral responses induced by transport pricing. Relevant dimensions of behavior include trip suppression, mode choice, and departure time choice. The results from a questionnaire among Dutch car owners are presented. The behavioral responses to two Dutch policy-relevant road pricing measures were analyzed. Depending on the type of measure, reductions of 6% to 15% were found in the number of car trips, which is in line with previous findings. A flat kilometer charge affects social trips considerably more than commuting trips. Respondents do appear to adjust commuting trips when a peak hour charge is implemented. Nonmotorized travel and trip suppression are the most popular alternatives for noncommuting trips. Departure time changes become attractive for all purposes when the proposed measure varies over time. Important explanatory variables for these effectiveness levels include the type of measure, income, and the possibility for commuters to work at home.
Desirable Length of Spiral Curves for Two-Lane Rural Roads
Authors: Perco Paolo
Published: May 2018

Most design standards recommend the use of spiral curves in the transition design. The advantages usually connected with their use are a gradual increase in the centrifugal force, a convenient arrangement for superelevation, and a satisfactory roadway appearance. However, some studies show a potentially negative effect of a long spiral transition on the driver's curve perception and safety. An analysis conducted on paths surveyed along 12 transitions with and without spiral curves confirmed the negative effect of excessive spiral length on driver behavior. The results of this analysis showed that the most desirable spiral length, which offers advantages in comparison with a tangent-to-curve transition, is equal to the distance traveled during the steering time. Therefore, a model to estimate the desirable spiral length for transitions of sharp horizontal curves on two-lane rural roads was developed on the basis of the data collected in three studies. Starting from the radius of the impending curve, the model calculates the desirable spiral length and gives a good description of real driver behavior, as observed in field surveys. The choice of the spiral length based on this model appears to be useful because the estimated length is consistent with the real distance traveled by the vehicle during the steering action, and this correspondence ensures optimal operating conditions for drivers.
Daytime High-Speed Passing Maneuvers Observed on Rural Two-Lane, Two-Way Highway
Authors: Carlson Paul J. , Miles Jeffrey D. , Johnson Patricia K.
Published: May 2018

Daytime high-speed passing maneuvers were recorded along a straight and flat 15-mi section of a rural two-lane, two-way highway in Texas. The posted speed limit was 70 mph. Passing maneuvers were covertly recorded from the overtaken vehicle, which was driven at three specific study speeds: 55, 60, and 65 mph. A total of 105 single-vehicle daytime passes were analyzed. Speed profiles of the passing vehicles’ passes were developed for each of the three studied speeds. The results were compared with AASHTO's assumptions and criteria for minimum passing sight distance (PSD) for two-lane, two-way highways. In particular, the analysis focused on the elements associated with a passing vehicle while it occupied the opposing lane of travel. The specific elements that were studied included these four: the average passing speed, the speed differential between passing and passed vehicles, the distance traveled while making the pass, and the total elapsed time. The general findings provided support for the AASHTO PSD model. For the assumptions made, the model provided reasonable results. However, the assumptions may need to be updated or to have more flexibility added. For instance, for a 70 mph design speed, the assumed speed of the overtaken vehicle is 54 mph in the AASHTO PSD model. The PSD associated with these speeds was verified in this study. But what if the overtaken vehicle was traveling at 60 or 65 mph? The results of this study show that the current AASHTO PSD model would provide inadequate PSD values for overtaken speeds greater than those currently assumed.
Operating-Speed Model for Low-Speed Urban Tangent Streets Based on In-Vehicle Global Positioning System Data
Authors: Wang Jun , Dixon Karen K. , Li Hainan , Hunter Michael
Published: May 2018

Low-speed urban streets are designed to provide both access and mobility and to accommodate multiple road users, such as bicyclists and pedestrians. However, speeds on these facilities often exceed the intended operating speeds, as well as their design speeds. Several studies have indicated that the design speed concept, as implemented in the roadway design process in the United States, does not guarantee a consistent alignment promoting uniform operating speeds less than design speeds. A promising design approach to overcome these apparent shortfalls of the design speed approach is a performance-based design procedure with the incorporation of operating speeds. However, this approach requires a clear understanding of the relationships between operating speeds and various road environments. Although numerous previous studies have developed operating-speed models, most of these studies have concentrated on high-speed, rural two-lane highways. In contrast, highway designers and planners have little information about the influence of low-speed urban street environments on drivers’ speeds. This study investigated the relationship between drivers’ speed choices and their associated low-speed urban roadway environments by analyzing second-by-second in-vehicle global positioning system (GPS) data from more than 200 randomly selected vehicles in the Atlanta, Georgia, area. The authors developed operating-speed models for low-speed urban street segments on the bases of roadway alignment, cross-section characteristics, roadside features, and adjacent land uses. The results of this research effort can help highway designers and planners better understand expected operating speeds when they design and evaluate low-speed urban roadways.
Hierarchical Fuzzy Inference System to Evaluate Expert Opinions on Median Safety
Authors: Lee Dongmin , Pietrucha Martin T. , Donnell Eric T.
Published: May 2018

Transportation experts may be asked to provide an opinion about a topic for various reasons. Most studies use simple statistical methods to aggregate these opinions. However, because experts use linguistic information and their own subjective decision criteria to formulate and express their opinions, this aggregation can ignore the unique characteristics of individual experts and the decision criteria they used. To overcome these limitations, a hierarchical fuzzy inference system was developed to evaluate the subjective opinions from transportation experts on median safety. Variables were selected from the results of a survey of transportation experts conducted as part of a previous study. The fuzzy membership functions for six selected variables were constructed through a review of the experts’ opinions and transportation safety references. The proposed fuzzy inference system was decomposed into two systems with a hierarchical structure to reduce the complexity of the multivariable fuzzy system. In the decomposed system, the degree of median safety, distilled from geometric and traffic flow conditions, was represented by a fuzzy median safety index (FMSI). Through comparison with observed median crashes, it was found that the mean cross-median collision (CMC) frequency and mean CMC crash rate increased exponentially with an increase of FMSI, typically for roadway segments with an FMSI equal to or greater than 0.7. The fuzzy inference system can then be used to estimate the likelihood of a median crash occurring within an individual segment of highway.
Upstream Signalized Crossover Intersection
Authors: Sayed Tarek , Storer Paul , Wong Godwin
Published: May 2018

Left turns have a significant impact on the operation and performance of signalized intersections. Therefore, researchers have investigated alternative measures to improve the performance of intersections with heavy left-turn movements, some of which have been unconventional schemes. One of these schemes is the upstream signalized crossover (USC), a four-legged intersection designed to eliminate left-turn-opposing conflicts by crossing the left and through traffic to the left side of the road at all four approaches prior to the intersection. Crisscrossing action is achieved through the use of a secondary two-phase signal at each crossover point. This research investigated signal optimization strategies for USC intersections and identified important operation issues. The VISSIM microsimulation program was used to model and analyze the unconventional USC intersection and, for comparison, a conventional intersection. The analysis revealed that, for relatively balanced volumes, a USC intersection can significantly reduce average vehicle delays, particularly when the volumes entering the intersection are relatively high. More important, the capacity of the USC intersection was found to be approximately 50% greater than that of a conventional intersection with similar geometry under balanced traffic volumes. For highly unbalanced volumes, particularly when the intersection volumes were relatively low, a conventional intersection outperformed the USC intersection. Overall, the USC intersection showed considerable potential for situations in which one or more of the following conditions exist: (a) intersection volumes are balanced and near or over the capacity of a conventional intersection, (b) traffic volumes are somewhat unbalanced, but the overall entering volumes are too high to be accommodated with a conventional intersection, or (c) the intersection has heavy left-turn volumes that cause excessive delays.
Role and Application of Accident Modification Factors within Highway Design Process
Authors: Lord Dominique , Bonneson James A.
Published: May 2018

Over the past few years, transportation agencies have placed greater emphasis on incorporating safety into the highway design process. The main assumption is that a highway designed with an explicit attention to safety could significantly reduce the frequency and the severity of crashes. One tool that is rapidly gaining popularity is the use of accident modification factors (AMFs) to estimate the change in safety following implementation of a countermeasure, a significant change in a geometric design element, or a planned construction upgrade of a highway facility. Although AMFs will play an extremely important role in coming years, especially with the forthcoming publication of the Highway Safety Manual (HSM), no document currently exists that addresses how they potentially could be used with the process to design highways. This paper describes the role and application of AMFs in the highway geometric design process. More specifically, it provides guidelines for applying these factors within the preliminary design stage, for assessing design consistency, and for evaluating design exceptions. For each design application, a proposed procedure is described in detail. Finally, an example is provided to illustrate more clearly the descriptions of two of the procedures.
Radius Requirements for Trucks on Three-Dimensional Reverse Horizontal Curves with Intermediate Tangents
Authors: Easa Said M. , Halim Amir Abd El
Published: May 2018

Minimum radius requirements for reverse horizontal curves are currently based on the design of each arc as a separate simple horizontal curve on flat terrain, with the effects of reverse horizontal curvature and vertical alignment being ignored. This paper establishes minimum radius requirements for trucks on three-dimensional (3-D) reverse horizontal curves with intermediate tangents on the basis of vehicle stability. With vehicle simulation software, vehicle dynamics were recorded for the base case of two-dimensional simple curves and for reverse curves superimposed with different vertical alignments (upgrade, downgrade, crest curve, and sag curve). The simulation was run for two maximum superelevation rates, three design vehicles, and different vertical grades. Two mathematical models were developed for flat and 3-D reverse curves. The models provided the minimum radius of the sharper arc of the reverse curve as a function of design speed, maximum superelevation, ratio of flatter to sharper curve radius, design vehicle, and intermediate tangent length. The results showed that an increase in the minimum radius of existing design guides (ranging from 5% to 27%) was required to compensate for the effects of reverse curvature and vertical alignment. The required increase can be reduced by using longer intermediate tangents. Design requirements for the spiral length of reverse curves are also presented.
Three-Dimensional Stop-Control Intersection Sight Distance
Authors: Easa Said M. , Ali Zain A.
Published: May 2018

Intersection sight distance is an important design element. A stopped vehicle on the minor road needs sufficient sight distance to depart (cross, turn left, or turn right) safely, even though an approaching vehicle on the major road comes into view. Current AASHTO policy assumes that both minor and major roads are straight and intersect at right angles. Previous research has addressed sight distance for stop-control intersections on three-dimensional alignments for obstructions inside the horizontal curve and for intersection and major-road vehicle (object) on the curve. The results of the research presented in this paper extend previous research work by (a) allowing the object to be anywhere on the horizontal curve or tangent, (b) allowing the horizontal and vertical curves to overlap partially, and (c) considering the case in which the obstruction lies outside the horizontal curve. The obstruction location was formulated through use of a simple variable that takes the value of +1 or −1 for an obstruction, respectively, inside or outside the horizontal curve. Design aids for the required minimum lateral clearances (from the minor and major roads) are presented for different radii of horizontal curve and major-road design speeds. Application of the model is illustrated through a numerical example. The presented model and guidelines, which are general and easy to use, should be of interest to highway designers.
Nonlinearity of Repeated Creep and Recovery Binder Test and Relationship with Mixture Permanent Deformation
Authors: Delgadillo Rodrigo , Cho Dong Woo , Bahia Hussain
Published: May 2018

It is recognized that the Superpave® binder rutting parameter (G*/sinδ) is not sufficient to evaluate binder contribution to asphalt mixture rutting. As a result of the NCHRP 9–10 project, a new dynamic shear rheometer test was introduced with promising results: repeated creep and recovery (RCR). For simplicity, the original RCR creep stress was 25 Pa so that the binder would stay in the linear range. However, there is evidence that stresses under traffic loads are high enough to make the binder reach the nonlinear range. This paper was prepared to cover the stress dependency of binders in the RCR test and the relationship with mixture performance. Eight different binders, modified and unmodified, were compared in the stress dependency. The relationship between binder and mixture performance was studied with mixtures prepared with two kinds of aggregates and seven different binders. Results show that the binder stress sensitivity varies significantly between binders on the basis of modification type and testing temperatures. Results of the mixture repeated creep show significant effects of modifier type and good correlation with results of the RCR of binders. For stresses until 10,000 Pa, the correlation between RCR and mixture permanent deformation is good in regard to the stress level selected. It was also noticed that binder samples that were able to withstand high levels of stress in the RCR test without collapse provided the mixtures with a lower amount of permanent deformation. The stress sweep using cyclic loading to measure G* relates well to the stress sensitivity measured with RCR.
Binder Oxidative Aging in Texas Pavements
Authors: Al-Azri Nasser A. , Jung Sung Hoon , Lunsford Kevin M. , Ferry Ann , Bullin Jerry A. , Davison Richard R. , Glover Charles J.
Published: May 2018

Aging of binders in pavements is much less understood than laboratory aging of neat binders because of a number of complications. Complications include suitable extraction and recovery methods; uncontrolled variables and unknowns such as mixture characteristics (e.g., air voids), maintenance treatments, traffic, and climate; sustaining of a research effort to study a given pavement during an appropriate time frame (in excess of one decade); and cost. An ongoing research effort sponsored by the Texas Department of Transportation studied binder oxidative hardening at 15 pavements across Texas. Results indicate that typically unmodified binders in pavements oxidize and harden to a degree that exceeds generally accepted pavement aging assumptions. In addition, this hardening may extend much deeper into the pavement than has been previously assumed or documented. Data suggest that pavements can oxidize at surprisingly uniform rates with depth once early oxidation occurs and that these rates continue for an extended time. As a rough measure, 1 month environmental room aging of 1-mm neat binder films at 60°C was equivalent to about 15 months in Texas Highway 21 after the early higher hardening rate period.
High-Pressure Gel Permeation Chromatography of Aging of Recycled Crumb Rubber–Modified Binders with Rejuvenating Agents
Authors: Shen Junan , Amirkhanian Serji , Xiao Feipeng
Published: May 2018

This paper presents a study that uses gel permeation chromatography (GPC) to characterize the aging process of blends of aged crumb rubber–modified (CRM) binders containing rejuvenating agents. Two aging processes proposed by SHRP binder specifications—rolling thin-film oven (RTFO) and RTFO + pressure-aging vessel (PAV)—were used for the aging of the blends. The GPC profiles—namely, the molecular size distributions—of the blends of aged binders and rejuvenating agents were measured by GPC, and different molecular sizes of these blends were calculated. Three aged CRM binders and two aged control binders of PG76-22 (3% styrene–butadiene–styrene–modified binders) were mixed with several percentages of either a rejuvenator or a softer binder to produce the blends. In addition, performance properties of these blends at three different aging states—that is, no aging, RTFO aging, and PAV aging—were tested and correlated with the larger molecular sizes of the GPC results. It was concluded that compositional changes of these blends due to the RTFO and RTFO+PAV aging processes were well reflected by GPC results. In addition, correlations between the large molecular size and the performance properties of the blends are rather good.
Compact Tension Testing of Asphalt Binders at Low Temperatures
Authors: Edwards Michelle A. , Hesp Simon A. M.
Published: May 2018

This paper documents and discusses the development of a compact tension (CT) test for the grading of asphalt binders. The geometry was chosen because it provides an easy way to obtain the plane-strain fracture toughness ( KIc), fracture energy ( Gf), and crack tip opening displacement (δ t) in brittle failure on a small sample. It is believed that the method will allow for a better ranking of binders in regard to their low-temperature fracture resistance. CT specimens were prepared in different sizes with varying notch depths. KIc was found to be constant, regardless of the notch depth or specimen width for both straight and modified binders. Gf was found to decrease with notch depth; this is thought to be the result of energy-absorbing mechanisms away from the crack tip. Deeper notches or an energy correction is able to account for that issue. A slightly different fracture energy, Jf, was obtained in a more direct fashion from the slope of a plot of the normalized failure energy ( Uf/B) versus notch depth ( a). Jf provided results close to those obtained with an energy correction from a single notch depth. Reproducibility of the fracture test was found to be good with pooled standard deviations of 5% to 10% for KIc and 15% to 20% for Gf, which is typical for such tests. Given the fact that brittle fracture properties can vary by orders of magnitude for binders of the same Superpave® grade, it is concluded that the test method has a high ability to reveal statistically significant differences in toughness.
Analysis of Premature Low-Temperature Cracking in Three Ontario, Canada, Pavements
Authors: Yee Patricia , Aida Bill , Hesp Simon A. M. , Marks Pamela , Tam Kai K.
Published: May 2018

An analysis of premature low-temperature cracking in three Ontario, Canada, pavements is documented and discussed. Two of the contracts consisted of a 50-mm single lift of hot-mix asphalt on recycled asphalt pavement; the third contract was a single lift overlay on a previously cracked pavement. All three pavements exhibited extensive transverse cracking during their first winter. The binders used in each of the surface courses were evaluated for possible deviations from specification requirements and for their susceptibility to cracking as a result of excessive reversible aging during cold storage. The reversible aging tendencies, as indicated by bending beam rheometer (BBR) tests after extended periods of conditioning, showed that although all three binders met the specification, they lost a considerable amount from their grade temperature as determined according to AASHTO M320 criteria. Fracture tests on the binders showed that properties in the brittle state were all considered to be poor, yet typical for unmodified materials. Fracture properties in the ductile state for the binder from the one overlay contract indicated that low resistance to ductile failure could explain the observed distress. The experience has further confirmed the need to develop an extended BBR test protocol as well as brittle and ductile fracture tests to exclude binders that will be susceptible to these types of failures for future paving contracts.
Controlling Performance of Crumb Rubber–Modified Binders through Addition of Polymer Modifiers
Authors: Abdelrahman Magdy
Published: May 2018

The use of tire rubber as a modifier to enhance the properties of asphalt mixes through the wet process has proved to be a successful procedure, but full control of the properties of crumb rubber–modified binders has been a challenge. The literature indicates a wide variation on adding rubber to asphalt and that the degree of success of rubber modification in AC mixes depends on several factors, the majority of which relate to the method of mixing, storing, and transporting and to construction technologies. Understanding the nature of the interaction process between asphalt cement and crumb rubber–modifier (CRM) helps explain the development of binder properties. This paper covers the wet process, a relatively different technology in the application of CRM in asphalt with virgin polymers used to control and enhance the performance properties of CRM binders. The paper provides some clear insights into the mechanisms by which the interaction, with and without the existence of polymer modifiers, takes place. Effects of the interaction process variables, time and temperature, are explained. Results of this research are based on monitoring the changes in the rheological parameters of the developed binder.
Comparing Fine Aggregate Angularity with Aggregate and Hot-Mix Asphalt Performance Tests
Authors: Bennert Thomas , Maher Ali , Bryant Matthew , Smith Joseph
Published: May 2018

The fine aggregate angularity (FAA) was determined for 13 fine aggregate sources (angular and round) and eight aggregate blends. AASHTO T304 Methods A, B, and C as well as the Kansas Department of Transportation test procedure KT-50 were used to determine the FAA value. The direct shear test and the compacted aggregate resistance (CAR) test were also conducted to provide a more performance-based aggregate parameter for comparison. Eight different aggregate blends were used to construct eight different fine-graded 12.5-mm Superpave® hot-mix asphalt (HMA) mixtures with similar gradation and volumetric properties. The HMA mixtures were tested in the asphalt pavement analyzer and repeated shear and frequency sweep at constant height test modes of the Superpave shear tester to evaluate their respective permanent deformation properties. Results indicate that for the fine aggregate sources used in the study, the FAA and CAR values correlated well, as did the CAR values with the angle of internal friction calculated from the direct shear tests. By a comparison of the FAA value of the aggregate blends with published criteria of the HMA permanent deformation tests, the Superpave-recommended FAA value of 45 was validated. Results of the HMA mixture testing and FAA comparison also allowed for the recommendation of a pass–fail CAR value for use in Superpave mix design.
Evaluating Recycled Asphalt Pavement Mixtures with Mechanistic–Empirical Pavement Design Guide Level 3 Analysis
Authors: Chehab Ghassan R. , Daniel Jo Sias
Published: May 2018

The main objective of this study is to assess the sensitivity of the predicted performance of recycled asphalt pavement (RAP) mixtures to the assumed binder grade. That is achieved with the Mechanistic–Empirical Pavement Design Guide (MEPDG) software to predict the performance of a specific flexible pavement structure with a RAP-modified hot-mix asphalt surface layer. Different design runs are conducted for which all the pavement properties and conditions are held constant except the properties of the surface layer. Specifically, a near-full factorial experiment is performed in which RAP content and effective binder PG grade are the main variables. Comparison of the predicted performance of the various runs reveals important findings on the extent and manner in which those two properties affect pavement distresses and performance. The influence of the assumed PG binder grade on the RAP mixtures, particularly the high-temperature grade, has a significant effect on the predicted amount of thermal cracking and rutting for the given structure. The predicted performance is especially sensitive to changes in assumed PG grade in the range in which the true effective PG grade is expected to fall; the difference from one PG grade to another can be the difference between a well-performing mixture and one that requires redesign. Results emphasize the importance of determining the effective binder grade of RAP mixtures. An added benefit of conducting the numerous MEPDG software runs is the identification of issues that need to be considered when incorporating RAP mixtures in pavement design using the software.
Low-Energy Asphalt with Performance of Hot-Mix Asphalt
Authors: Romier Alain , Audeon Maurice , David Jac , Martineau Yves , Olard François
Published: May 2018

The paper presents an original process to produce a warm asphalt mixture: low-energy asphalt (LEA) with the performance of hot-mixasphalt(HMA). The Kyoto agreements continue to divide the planet, while protocol signatories are defining their application conditions. People wonder what the resulting repercussions will be on their respective fields of activity and their quality of life. A new aggregate coating technique is being presented in that context. The technique, the LEA process, substantially reduces energy consumption and greenhouse gas emissions. The low-energy coating technique LEA (EBE, from the French “enrobage à basse energie” involves the manufacture and application of asphalt mixes at a temperature lower than 100°C. These mixes offer a performance equivalent to that of HMA. They combine the action of the mixing energy, temperature, and water on the components of the mix, its bitumen, and aggregate skeleton. The originality of the process lies in the best use of changes in the condition of the bitumen: fluid when it is hot and able to transform into foam or to emulsify when in contact with water. Moreover the moderate-temperature heating of only the chippings (coarse aggregates) is involved; the rest of the aggregate skeleton is used cold and wet. This technique yields a significant saving in mixing energy and reduces the resulting gas emissions. The paper looks briefly into the process and sets it within its appropriate context.
Determination of Lime in Hot-Mix Asphalt
Authors: Arnold Terry S. , Rozario-Ranasinghe Muriel , Youtcheff Jack
Published: May 2018

Lime is added to hot-mix asphalt to mitigate stripping and other modes of moisture damage. No standard forensic test exists for the measurement of the lime content after it has been incorporated in the asphalt. This paper evaluates several methods to quantify the amount of hydrated lime (calcium hydroxide) in asphalt. A rapid analytical technique, Fourier transform infrared spectroscopy, was identified for determining the quality and quantity of lime. It yields qualitative or semiquantitative results from samples as small as 10 mg. No sample preparation is involved, and the binder can be scraped directly from large stones in the hot mix. The analysis can be completed in 30 s and offers the possibility of timely adjustment to the mix. For more accurate quantitative measurement, a second procedure is recommended. Samples are taken from cores with a hammer drill. The lime is separated from the resulting dust by acid extraction, and the calcium level is determined by atomic absorption spectroscopy or ion exchange chromatography. Different methods for removing the binder are discussed.
Vessel, Firm, and Lock Efficiency Measures in Lock Performance
Authors: Wilson Wesley W.
Published: May 2018

The inland waterway system is made up of a set of rivers and associated locks and dams. Dams establish “pools” of water that allow rivers to be navigated, and locks allow barges to pass from pools of different elevations. Lock performance (i.e., the timely passage of barges through the waterway) depends on many factors. This study examines lock performance in terms of the structural design of locks; the characteristics of the flotilla (vessels and barges); a set of state conditions (weather, river levels, etc.); and characteristics of vessels, locks, and firms. Vessel, firm, and lock efficiency measures are developed by using panel data techniques, and observed factors that influence efficiency are evaluated. The results indicate considerable heterogeneity across vessels, firms, and locks, which results in significant differences in timely passage through the locks.
Increasing the Attractiveness of Inland Waterway Transport with E-Transport River Information Services
Authors: Pfliegl Reinhard , Bäck Andreas
Published: May 2018

Inland navigation must enhance its service quality to gain from the increasing transport demand in Europe. This requires the provision of reliable fairway conditions and innovative information services. Telematics services to support traffic and transport management [River Information Services (RIS)] will improve the information processes of inland navigation. RIS provide fairway users and authorities with geographical, hydrographical, and regulatory information supported by standardized electronic navigational charts. Temporary restrictions of fairways are published by means of language-independent notices to skippers. Transportation of dangerous cargo is announced electronically, which enables authorities to be prepared for disasters. Vessel tracking and tracing enhance lock, bridge, and terminal management as well as law enforcement. In addition to these basic services, e-transport applications provide advanced services for governmental and commercial users. To promote the harmonized implementation of RIS, the European Union established a legal framework in September 2005. The framework comprises binding rules for onboard equipment and data exchange as well as minimum requirements for future RIS implementations. Austria will be the first country to comply with this legislation. The Austrian RIS system provides electronic navigational charts, including water depth data and notices to skippers, electronically. Inland automatic identification system transponders are used for vessel tracking and tracing, and electronic reporting of dangerous cargo is possible electronically. The full implementation of RIS on the Danube (nine countries, 2,400 km) is expected in 2008. This will improve safety, efficiency, and the environmental friendliness of inland navigation and will contribute toward modal shift.
Hub-and-Spoke Networks in Container-on-Barge Transport
Authors: Konings Rob
Published: May 2018

Container-on-barge (COB) transport has developed successfully in Europe during the past two decades, but this transport business has been focused primarily on maritime container flows and therefore developed as a typical hinterland transport system. This paper postulates that increasing the market share of COB transport, and in particular opening up new geographical markets, would require transport services in addition to the existing line and point-to-point barge services. The central question is whether hub-and-spoke (H-S) services could be a fruitful tool in improving the performance of COB transport and so in gaining market share. The typical cost, service, and geographical characteristics of H-S networks are discussed and illustrated with examples from the airline industry, which has a rich history in H-S research and applications. These general features of H-S networks are used as a framework to explore the feasibility of H-S networks in COB transport. The conditions and implications of operating these networks in barge transport are discussed. The discussion indicates that an H-S network can result in efficient barge services, because it can make a vessel most productive through optimized sailing schedules and more efficient use of vessel capacity in case of differences in waterway dimensions. A major precondition, however, is a cheap, fast, and reliable exchange of containers in the hub terminal.
Study of Parametric Rolling Event on a Panamax Container Vessel
Authors: Carmel Stephen M.
Published: May 2018

In January 2003 the Maersk Carolina, a Panamax container vessel, encountered a storm in the North Atlantic en route from Algeciras, Spain, to Halifax, Nova Scotia, Canada. The vessel experienced gale-force winds and seas in excess of 10 m. During one particularly violent rolling and pitching event, the vessel quickly and unexpectedly began rolling upwards of 47 degrees. During this incident 133 containers were lost overboard, and 50 others sustained moderate to severe water damage but remained on board. Cargo claims exceeded $4 million. The vessel itself sustained moderate structural damage. Results of a simulation and modeling study of the event are presented, and they indicate that the vessel had experienced parametric rolling, a little-understood and unexpected risk for certain container vessel designs. The simulation further showed that in tiers where containers were lost, excessive compression forces acting on the lower on-deck container tiers exceeded the strength of the corner posts, which would cause containers in these tiers to collapse and result in a catastrophic failure of the lashing system. All simulation results correspond closely to what was observed on the vessel. A brief introduction to vessel design and weather factors leading to parametric rolling is provided. New wave sensing technology, advanced on-board analysis software similar to that used in the Maersk Carolina study, and precise vessel motion measurement technology currently under development are described. These innovations will allow masters to make more informed navigational decisions and avoid parametric rolling events in the future.