Triple left-turn lanes have been used to reduce vehicle delays, queue lengths, and left-turn storage bays at signalized intersections with relatively higher left-turn demand. Limited research has been conducted to study capacity issues and how they relate to various geometric configurations of triple left-turn lanes. This study analyzed the influence of a number of geometric factors found at 15 triple left-turn lane sites in Florida on saturation flow, lane usage, and lane utilization. A total of 2,395 lane cycles and 38,023 vehicles were observed. The observed saturation flows yielded a mean saturation flow of 1,859 vehicles per hour of green per lane (vphgpl) with the 95% confidence interval of 1,810–1,907 vphgpl. The analysis of variance (ANOVA) test was used to determine statistical significance of the variables’ influence on saturation flows. In addition, multivariate analysis of variance (MANOVA) was conducted to determine the influence of interaction of variables. The results showed that triple left-turn lanes on downgrades and with angle of turn less than 90° were the two factors that mostly contributed to the high saturation flow while triple left-turn lanes located on one-way streets and on approaches which are curved had the lowest saturation flow. It was also found that street type significantly influenced saturation flow results when combined with other variables. The lane utilization was dependent on the geometrics of the intersections in which shadowed left-turn lanes (one or two left-turn lanes added in the vicinity of the intersections as storage lanes) had lower utilization of the innermost lane compared to unshadowed lanes.

In this study, the goal attainment method is implemented for the optimization of speed control hump profiles. Basic dimensions for a number of hump profile functions are optimized for single vehicles classified in five categories and for a specified distribution of these vehicles. Objective functions are selected as combinations of the longitudinal and vertical acceleration components at pre-specified points on the vehicle body. The main objective is to minimize vehicle response functions below the hump crossing speed limit and to maximize them above the speed limit. Typical characteristics of a series of two axle vehicles, described by the half car model, are used and the performances of various hump profiles are assessed.

Departments of Transportation throughout the United States and elsewhere employ close-circuit television (CCTV) cameras for roadway monitoring as part of increasingly sophisticated traffic management systems. Cameras used for this purpose are attached to various highway structures and poles as high as $65\mathrm{ft}$ , all susceptible to wind- and ground-induced vibrations which adversely affect image quality. This paper describes the engineering analysis, development, and testing of a low-cost, biaxial mechanical vibration isolator specifically aimed at horizontal high-frequency motion abatement in pole-mounted camera applications and similarly conditioned supports. The device works on the principle of force and displacement transmissibility reduction via the use of a lightly damped sprung interface with a tuned natural frequency. The isolator is inserted between the top of the structure (pole) and the seat of the camera, and operates by rejecting undesirable high-frequency modal vibrations experienced by the main support; this has the effect of diminishing high-acceleration ground inputs which are principally responsible for image distortion. While favorable to high-frequency performance, the physics of this configuration prescribe the presence of a low-frequency displacement or pan of the sprung mass (albeit found to be free of blur in experiment). This characteristic is complementary to that of electronic image stabilization technology, whose performance suffers when significant motion is present in the incoming video feed. For this reason, the proposed mechanical solution is presented as an ancillary technique to image processing in installations where high frequency or displacement conditions prevail at the camera support.

The short service life of rail turnouts and the related noise and vibration disturbance, are directly related to their dynamic distress. Especially in the case of urban rail systems, such problems are amplified due to the increased train frequency and the proximity to inhabited structures. This paper presents three new concepts for the reduction of noise and vibration produced by railway turnouts in urban railway lines, and provides an assessment of their performance. The effectiveness of the three new concepts is first evaluated analytically, using two different methodologies, earlier validated against line measurements on existing turnouts. Then, the actual performance of one of the three concepts, along with the effectiveness of the two analysis methodologies, is verified through real-scale measurements. Based on the presented analyses, all three new concepts are shown to provide a substantial enhancement of turnout performance. Furthermore, soil conditions and soil-structure interaction are shown to play an important role in the behavior of the investigated systems.

This paper demonstrates that in addition to intracycle demand fluctuation, which is already a consideration in many delay models, intercycle demand variance also impacts average delay at signalized intersections. Webster-type delay models treat demand fluctuation over the whole analysis period, often $15\min$ or longer, as if it were just within a single cycle. Such an approach is fine if used judiciously, one might presume. However, results from Monte Carlo simulations with the incremental queue accumulation (IQA) method indicate that Webster-type delay models will underestimate the average delay under heavy traffic conditions. As unutilized capacity at a signalized intersection cannot be saved or carried over to be used by succeeding cycles when demand surges due to normal fluctuation, better understanding of the patterns of intercycle demand variance is important. Simulation results demonstrate that different patterns of intercycle demand variance can result in different levels of average delay. A low-to-high demand pattern will cause a higher average delay than a high-to-low pattern would, even though the overall demand level is exactly the same. It is therefore clear that neglecting intercycle demand variance may lead to significant inaccuracy and, hence, suboptimal signal timing decisions.

This paper is aimed at estimating the time available for compaction of a hot-mix asphalt mixture during night construction. Laboratory tests were conducted on dense-graded and porous asphalt (PA) mixtures to evaluate their mechanical properties. Temperatures and mix characteristics tested in the laboratory were determined to be those typically found in an asphalt lift from initial laydown through final compaction. In field, thermocouples were installed at different depths to measure temperature changes to decide pavement cooling times of the same mixes as used in the laboratory. The cooling behavior of asphalt concrete could be classified into the following three stages: rapid, transition and stable zone. The air void in the PA mix was found to contribute to heat loss and result in a rapid cooling rate when compared to that in a dense-graded mix. The cooling rate at depth of 0, 2.5, and $5\mathrm{cm}$ showed an essential difference in the cooling rate initially. As the cooling process continued, the cooling rate became stable and reached a thermal equilibrium condition. An increase in lift thickness was shown to increase the compaction time. However, an increase in layer thickness more than $10\mathrm{cm}$ might not increase the time available for compaction significantly. A regression model was developed to predict the time required to cool to the minimum temperature allowed for compaction at night. The predicted values were in good agreement with those measured in the field. This study shows that a simplified method to predict available compaction time can be developed by considering only the significant factors affecting pavement cooling.

Pavement preservation programming often involves multiple objective considerations. Traditional single-objective optimization frameworks consider one single objective while imposing competing objectives as constraints in the optimization formulation. This paper proposes an approach for pavement preservation programming that uses multiobjective optimization and chance constraints. This approach can handle multiple incommensurable and conflicting objectives while considering probabilistic constraints related to the available budget over the planning horizon. The implementation of the approach in a case study with two conflicting objectives of: (1) maximizing the network level of service in terms of weighted average state condition; and (2) minimizing the total preservation cost, shows that its application provides a practical and flexible tool to determine optimal allocation of resources for pavement preservation that reflects agency goals, resource limitations, and performance targets.

To better understand the characteristics of traffic congestion and efficiently employ congestion measures for interstate highway systems, this study examined the limitations of the congestion measures currently in use such as the percent of congestion and the duration of continuous congestion. Based on this study, these congestion measures provided different results of the congestion severity for even the same interstate highway segment, which means that the use of a single measure might not give a reliable evaluation result. In order to minimize the potential bias and enhance the advantage of each congestion measure, this study proposed a composite congestion severity measure by combining congestion information of both percent of congestion and duration of continuous congestion measures. The writers found that the proposed composite congestion severity measure efficiently identified the levels of the congestion severity of interstate highway segments and that it could be instantly accomplished with the existing loop detector count systems in most states. This proposed measure may be a potential candidate for describing levels of congestion severity and can provide a proper guideline for transportation engineers or decision makers to efficiently allocate available budget and resources to correct applicable interstate segments.