A weak railway subgrade may lead to instability of the railway track system. The condition of a railway subgrade is typically evaluated using trial pit excavation and a portable ballast sampler, which may severely disturb the ballast layer. Also, nondestructive geophysical techniques, such as ground penetrating radar (GPR), are used to investigate the condition of the ballast and subgrade along the track. The objective of this study is the development and application of a cone penetrometer with a helical-type outer screw rod (CPH) that minimizes the disturbance of the ballast layer for the evaluation of the subgrade condition by measuring the resistance of the cone tip. The CPH consists of a helical-type outer screw rod (helical rod) and a mini cone penetrometer inside the rod. The design concerns include easy installation of the helical rod into the ballast layer, the reaction force of the mini cone penetrometer, installation of the strain gauge, and calculation of the cone tip resistance. The helical rod, which penetrates into the ballast layer with a rotation force, provides the reaction force for the mini cone penetration test. The mini cone penetrometer with a diameter of 15 mm is pushed into the subgrade (sand layer) at the penetration rate of $1\mathrm{mm}/\mathrm{s}$. In addition, dynamic cone penetrometer (DCP) tests are carried out to compare the cone tip resistance with the DCP index (DCPI). Field application tests reveal that the cone tip resistance increases with an increase in the depth and is inversely proportional to the DCPI. On the basis of the cone tip resistance, the soil types of subgrade at three sites are classified as sandy silt to silty sand. This study suggests that the CPH may be a useful device for providing a reliable geotechnical parameter and estimating the subgrade condition with minimal disturbance of the ballast layer.

This paper presents a network-level structural capacity indicator for asphalt pavements in the state of Virginia. A literature review revealed that several network-level structural capacity indexes have been proposed, and a number of states use structural capacity measures in their network-level decision processes. Some decision methods and structural indexes are compared in this paper using network-level deflection data collected using the falling weight deflectometer and distress data from tests conducted on Virginia interstates. One index that is based on the structural number concept, the Structural Capacity Index, is found to produce network-level decisions that most closely match project-level work done by the Virginia Department of Transportation during the 2008 construction season. The index was adopted, and its sensitivity to various input parameters was determined. Furthermore, the impact of the structural capacity of the pavement on the service life of a pavement maintenance treatment was clearly established in this paper. Equations to define the service life of a corrective maintenance treatment as a function of the structural condition of the pavement are also presented in this paper.

The curling and warping of rigid pavements are the results of temperature and moisture gradients varying with depth, creep, and other factors, including construction. The indicators commonly used to evaluate slab deformation include a combination of deflections derived from a heavy-weight deflectometer (HWD) that are measured at specific locations on pavement slabs. Indicators comprise the sum of deflections (SD) across the joints and the impulse stiffness modulus (ISM) deflection ratio. The objective of this study was to identify the best indicator that can be employed for assessing the slab curling level relationship to temperature. The study was included in a project developed by the U.S. Army Engineer Research and Development Center (ERDC) and sponsored by the Federal Aviation Administration (FAA). At selected military bases, HWD testing on concrete slabs was executed on two different occasions toward the end of summer and in winter. These tests were conducted to monitor slab deflections under different temperature conditions to quantify a correlation between measured deflections and temperature. The analysis showed that the SD rather than the ISM ratio could be adopted as an indicator to determine the relative degree of slab curling. The proposed approach to analyze deflection parameters showed promising results, and with a dedicated database and intensive testing, it is believed possible to refine the regression analysis and increase its level of determination. The proposed methodology for analyzing SD and temperature differences can be adopted in those cases intended to evaluate curling trend relationships to construction or curing techniques.

Departments of Transportation (DOTs) rely heavily on chloride-based treatments for winter road maintenance despite the well-documented effects of these chemicals on infrastructure and the environment. Proposed alternative treatments have yet to be widely adopted because of economic and technical limitations that are largely outside of the control of the DOT. This work explores the application of winter maintenance chemicals with a life-cycle approach to understand which actions a DOT can take to reduce the negative life-cycle environmental impacts of these activities. Three representative treatments and/or best management practices are compared: conventional rock salt, calcium magnesium acetate (CMA), and preemptive treatments of roadways with a brine of salt and/or CMA. The results conclusively show that CMA, which has been widely touted as an environmentally preferable, if more expensive, alternative to chloride-based treatments, has considerably higher environmental impacts over its entire life cycle. Most of these burdens are associated with the upstream production processes required to generate the CMA. The salt-based treatments consume considerably less water, energy, and generate fewer greenhouse gases and biochemical oxygen demand in receiving waters. Applying the chloride chemicals as a brine rather than in the dry form results in important reductions in all environmental impacts over the entire life cycle. This result is consistent for a variety of climate conditions (e.g., representative of coastal, piedmont, and mountain climates) considered for this study, which used historical weather data from Virginia. Because DOTs can affect appreciable improvements in efficiency by using brines, sensitivity analysis identifies the activities specifically resulting in the most important environmental improvement on a systems basis. The DOT-controlled steps with the greatest potential for improvement include reducing the energy consumed for the salt application process and implementing practices that reduce total storm water runoff to reduce chloride loading.

An adequate evaluation of stress developments in concrete is essential to ensure well-performing and long-lasting portland cement concrete (PCC) pavement designs and construction. In this study, the effects of creep and built-in curling (BIC) on the stress history of PCC pavements under environmental loadings were investigated primarily through a series of field tests and numerical data interpretations. To identify the stress-dependent strain component within the in situ measured total strain, a nonstress cylinder (NC) was employed in the field tests. The identified stress-dependent strains from the field tests were converted to stresses using a step-by-step numerical method. To investigate the effect of creep on stress developments, stress histories were computed in two different ways—one with elastic analysis and the other with viscoelastic analysis—and then their difference (stress relaxation) over time was evaluated. The finding indicated that creep may be a key element in the evaluation of long-term stresses and, in turn, the design and analysis of PCC pavements. Furthermore, this study examined the impacts of BIC on the residual stresses of PCC pavements. The result showed that BIC may affect the early-age stress development, but it has little influence on the long-term environmental stress state.

This study evaluated the effects of portable plastic rumble strips (PPRSs) on speed reduction and drivers’ behaviors in advance of flagger-controlled work zones. Travel speed data were collected at three two-lane highways with temporary (less than a day) maintenance activities, at which standard flagger traffic control was set up with or without the implementation of PPRSs. Drivers’ reactions to the PPRSs, such as changing lanes and braking in the vicinity of the PPRSs, were also investigated when the PPRSs were in place. The results showed that drivers became more cautious because of the PPRSs. The PPRSs reduced car mean speeds by 9.7 to $22.2\mathrm{km}/\mathrm{h}$ (6.0 to $13.8\mathrm{mi}/\mathrm{h}$). They also decreased the 85th percentile of car speeds at two field test sites. It was observed that 30 to 80% of all drivers activated their brakes when they approached the PPRSs close to the flagger. In addition, about 5% of car and truck drivers swerved around the PPRSs. This indicates that additional signing or other supplemental traffic devices would be needed when the PPRSs are implemented.

The objective of this research was to define eventual differences in models of pedestrian behavior at signalized pedestrian crossings, with and without countdown displays. The outcomes of this work represent a contribution to the harmonization of positions on the effect of a countdown display on pedestrian behavior. Video recordings at two completely similar pedestrian crossings enabled the collection of pedestrian behavior data (crossing at the red light), which included different categories (gender, age, individual/group, and “slow” pedestrians), collected in different conditions (during certain red light intervals and traffic volume). The results of the research showed that a statistically significant larger number of pedestrian offenders occurred at pedestrian crossings without countdown displays rather than at crossings with countdown displays. The presence of a countdown display significantly reduced the number of women offenders in particular. The number of offenders in the first and last four seconds of the pedestrian red light at the pedestrian crossing with a countdown display, differed, in terms of statistical significance, from the number of offenders at the crossing without a countdown display. The countdown display had a positive influence on pedestrians older than 40 years of age, as well as on slow pedestrians.

Operational performance of right-turn-on-red (RTOR) at signalized intersections is a function of drivers’ gap-acceptance behavior. The objective of this study is to characterize gap-acceptance behavioral patterns of individual RTOR drivers turning from dual right-turn lanes. On the basis of direct field observation, binary logit models were developed, calibrated, and validated, and the attributes that have significant effects on gap-acceptance decisions were identified. The proposed model showed an improved capability of predicting gap-acceptance decisions as opposed to conventional, deterministic methods that may overrepresent aggressive drivers, whereas the deterministic method represents a reasonable trade-off between accuracy and ease of use for dual right-turn lanes. For RTOR drivers turning from a curb right-turn lane, the critical headway decreases on average as they are waiting for an acceptable gap. RTOR drivers turning from an inside right-turn lane did not demonstrate statistically significant evidence of increased impatience while waiting.

Current analytical methods to estimate the pedestrian level of service (PLOS) usually only consider a narrow range of pedestrians and may not be applicable for more diverse pedestrian populations with different characteristics. The aim of this study is to conceptualize the disabled pedestrian level of service (DPLOS) for different street hierarchies not previously addressed to ensure inclusive walking conditions. An analytical point system comparing existing pedestrian facilities to a standard is proposed to estimate the DPLOS. Although this practical model is only used for one case study in Singapore, the use of international standards would make this model universally applicable.

Intersection performance, in terms of the degree of complexity and efficiency defined from a traffic conflict point of view, was studied for this paper. The degree of intersection complexity was determined by conflict points and the probability of conflict at intersections, whereas intersection efficiency was determined by average velocity, volume, and conflict intensity. The corresponding parameters were adopted to construct models to calculate the degree of intersection complexity and efficiency. A case study was conducted by using three types of intersection layouts that are commonly seen in the field. A quadratic model was founded to describe the relationship between the degree of complexity and efficiency. The results of this study will be helpful in guiding intersection planning and design by optimizing intersection efficiency through controlling its degree of complexity.

Microscopic vehicle behaviors, such as car following, overtaking, and lane changing, may occur differently on links with different numbers of lanes. Thus, this paper addresses the impact of the number of lanes on the platoon dispersion of traffic flow in low-friction conditions. A well-adopted dispersion model is used to reflect the platoon dispersion. The platoon dispersion factor of the model is then recalibrated using data on road segments with different numbers of lanes. The data are obtained from a comprehensive survey taken at several locations on the arterial streets of Changchun and Hangzhou city, China, where each direction of road segment has two, three, four, or five lanes. The statistical results verify that the number of lanes does have an evident effect on the platoon dispersion factor α: when the number of lanes grows from two to five, the value of $\alpha$ decreases significantly; meanwhile, the slope of the function curve between $\alpha$ and the normalized flow becomes larger.

The design and planning of pedestrian walking facilities must be undertaken in the context of the prevailing and future local traffic composition. The latter is changing rapidly as a result of demographic changes such as aging population and obesity trends. If the traffic consists of a significant proportion of various pedestrian groups, some form of adjustment factor may need to be introduced in the dimensioning process. This paper introduces the concept of standard pedestrian equivalent factors as a practical systematic methodology when dealing with heterogeneity in pedestrian flow. Pedestrian microsimulation was employed to evaluate hypothetical pedestrian proportions to generate corresponding flow relationships. To estimate the factors, the equivalent time-space concept was utilized in order to consider the effects of the differences in physical and operational characteristics of pedestrians, particularly walking speed and body sizes. These characteristics were varied across different flow conditions, walkway widths, and proportions of other pedestrian types in the study sensitivity analysis. A case study was also conducted by utilizing field-collected data in order to illustrate the significance and relevance of the methodology in determining walkway widths.

The railroad blocking problem (RBP) is an important decision for freight railroad companies. The objective of this problem is to minimize the costs of delivering all commodities by deciding which interyard blocks to build and specifying the assignment of commodities to these blocks. In this paper, a mathematical model is presented for the RBP on Iran Railways. Its decision variables identify blocking scheme and demand assignment to these blocks. The RBP in medium and large sizes is not solvable with any commercial software available in the market. Therefore, a solution method based on tabu search algorithm is proposed for the suggested model. For evaluating the proposed algorithm, several simulated test problems are randomly generated and solved. The obtained results on the test problems are compared with those of solutions generated by CPLEX software. The comparison shows high efficiency and effectiveness of the proposed algorithm. The proposed model and solution method are applied to build a blocking plan for the Iranian railway.

The configuration of service facilities, such as ticket vending machines, staffed ticket booths, automatic fare gates, and escalators, is an important issue for the plan and design of rail transit stations. Reasonable configuration of service facilities is based on a good understanding of the passenger traffic characteristics of such service facilities, which are affected by passenger characteristics, station types, and facility performance. To study the passenger traffic characteristics of service facilities, five stations are selected in Shanghai, and their passenger traffic data are collected and analyzed. In this study, the results indicate that service-time frequencies of ticket vending machines and staffed ticket booths follow Weibull distribution and exponential distribution, respectively, and that the headway of passengers passing the automatic fare gate under ideal conditions follows normal distribution. According to the service time and headway distributions of ticket-selling facilities and automatic fare gates, the derived capacities of ticket vending machines, staffed ticket booths, and automatic fare gates are 137, 186, 253, 368, and $1,500\mathrm{passengers}/\mathrm{h}$, respectively. In addition, theoretical analysis and field survey of escalators show that escalator capacity is between 4,700 and $5,200\mathrm{passengers}/\mathrm{h}/\mathrm{m}$. It is found that the capacities of ticket-selling facilities and escalators in this study are far lower than those in China’s design codes. The capacity of automatic fare gates in this study is a little lower than that in China’s code; however, it is a little greater than that from the corresponding U.S. capacity manual.

In this paper two vertical alignment profiles (labeled dipped and undipped) connecting rail transit stations with different elevations are compared. A deterministic simulation model is developed and used to analyze train motion and energy use for three different vertical alignments. To minimize the cost of rail transit operation for both directions, cruising speed is optimized as a decision variable while train operations are simulated on the proposed vertical alignments. The numerical analysis and sensitivity studies show that the developed deterministic simulation model is useful for comparing vertical alignments, and that the proposed alignment concepts can significantly reduce travel time, energy use, brake wear, operating cost, and total cost compared with the baseline alignment profile.

Location planning for pedestrian zones is a multifaceted problem. The selection of best location from a list of potential stations involves consideration of different technical, economical, environmental, and social factors. For some of these factors, numerical values can be provided, but the others are based on the qualitative data. In this paper, a multicriteria decision analysis approach is presented based on analytic hierarchy process (AHP) for location planning of pedestrian zones under lack of quantitative data. A decision-making committee comprised of representatives of city transportation officials, public administration, and city residents or users is formed to select the criteria/subcriteria for evaluating pedestrian zones. Five locations for pedestrian zones are considered for evaluation in the city of Montréal: namely, Downtown, Jean Drapeau, Olympic stadium, Old Montréal, and Saint Denis. The results of this study indicate that the downtown area is the best choice for a pedestrian zone. Sensitivity analysis is conducted to determine the influence of criteria and subcriteria weights on the decision-making process.