The signalized diamond interchange is a widely used intersection design for freeway-to-arterial connections. The capacity of these interchanges is largely determined by the number of lanes, the demands of the various movements, the storage spaces for different movements, and the signal-timing strategies. This paper studies the advantages of using dynamic reversible lanes for left-turn movements. In traditional diamond interchanges, the bay lengths cannot change; however, if signal times are adjusted to give more time to an approach when traffic counts are heavier in one direction (such as the shifts between morning and evening peak), this limitation in capacity can be mitigated. In this work, several diamond interchange designs are studied. The optimized traditional diamond interchange performance is compared, in simulation, to the proposed dynamic reversible lane case. Situations are identified in which a dynamic reversible left-lane control would be beneficial in reducing delay and increasing throughput for the interchange.

The highway maintenance sector within the United Kingdom consumes considerable amounts of natural resources and accounts for a large amount of carbon emissions. Carbon emissions reduction is now considered an integral part of tender selection criteria and project performance issue by highway clients. This requires contractors to be able to assess and reduce both direct and indirect emissions associated with highway maintenance. This presents a challenge for the sector as despite the availability of methods to assess carbon there are no routine tools to allow a lifecycle assessment (LCA) approach to carbon reduction as part of ongoing maintenance management. Thus, there is a need for a consistent, project-focused carbon assessment tool, underpinned by a robust LCA methodology that can assess emissions and emissions reduction across core highway maintenance processes. This paper describes the development and business implementation of such a tool based on the Publicly Available Specification (PAS) 2050 protocol. The protocol is an independent standard developed by the British Standards Institution (BSI) in 2008 and updated in 2011 to produce a consistent approach for lifecycle emissions assessment from goods and services. It offers an iterative process, where the scope and objectives of the assessment are defined, relevant data collected for analysis and interpreted within the scope and system boundary defined by the standard. Twelve case studies were undertaken using the tool and the results demonstrated the tool’s potential to produce credible emissions information that can be integrated into highway maintenance decision-making processes. The tool identifies areas of emissions hotspots, opportunities for reduction, and then establishes a reduction hierarchy that can allow emissions reduction efforts to be prioritized in lifecycle terms. The study further presents sensitivity analyses with respect to choice of fuel, distance to site, material transport mode and distance, and design life of pavements. Although the implementation of the tool presented in this paper is specific to pavement resurfacing works, the tool can also be used to assess carbon emissions for other core highway maintenance processes, such as road marking, street lighting works and grass cutting, with the potential to evaluate full environmental impacts (e.g., Toxicity, Acidification and Ozone formation) associated with such highway maintenance processes.

Right-turning vehicles (in countries where vehicles driving on the left-hand-side of the road, e.g., UK, Australia) have large impacts to the operation of intersections. This paper focuses on a traffic maneuver for right-turning vehicles, named the hook turn (HT), which has been successfully implemented in Melbourne for over 50 years. To fully assess the operational performance of the intersection with the HT, two similar intersections are established by a computer model. One intersection plan has the HT maneuver, named the HT plan, and the other one has no HT maneuver, named the traditional plan. Both plans adopt the actuated control method (ACM) for signal settings. For the HT plan, a strategy is developed to cope with the spillover of HT vehicles using the loop detector data; dynamic adjustment of minimum green times is incorporated. With different traffic volumes and vehicle ratios, 24 simulation scenarios are designed. Two classes of indices, average delay and number of vehicles crossing the intersection per hour, are used to assess the performance of the two plans. The simulation results show that the HT plan can only reduce the average delay of through vehicles when the total intersection volume and the ratio of right-turning vehicles are high, and the vehicle capacity of the HT plan is, in general, greater than that of the traditional plan in most scenarios.

Trucks move around 70% of the freight weight in the United States. The combination of increased commercial motor vehicle traffic, tighter delivery schedules, and federally regulated limits on driving time lead to a nationally recognized problem on interstate highways in the United States, i.e., increased demand for commercial truck parking. Unavailability of sufficient parking spaces at rest areas results in illegal and unsafe parking at entrance/exit ramps, and other unauthorized areas. The research reported in this paper, funded by the Florida DOT, sought to understand the truck parking problem in Florida, determine the supply and demand characteristics for commercial truck parking, assess technology that can be used to improve parking management, and conduct a pilot project to test a smart truck parking-management technology to make better utilization of commercial parking spaces at public rest areas.

This paper examines the problem of determining the relation of variables and deterministic parameters of the optimum solution space for bus service zones within an urban transit model, due to the ever-evolving need for an efficient and effective transit system in modern society. A positive solution for the length of a local bus service zone was proposed and proven. Moreover, the Newton method was applied to derive a convergent sequence faster than the alternate sequence proposed in a previous paper. This analytic model will help transportation operators determine the optimum dimensions of bus service zones with great accuracy and will influence other tasks such as budget allocation.

Traffic signs are important roadway assets that provide critical guidance, including regulations and safety-related information, to road users. Traffic signs need to be inventoried by transportation agencies. However, the traditional manual methods carried out in the field are dangerous, labor-intensive, and time-consuming. There is a need to develop alternative methods to cost-effectively inventory traffic signs. The research reported in this paper, sponsored by the U.S. DOT Research and Innovative Technology Administration Program, is to critically assess an alternative traffic sign inventory method using mobile light detection and ranging (LiDAR), and inertial navigation system (INS), technologies. The contribution of this paper is three-fold, as follows: (1) an alternative traffic sign inventory method is proposed using mobile LiDAR and INS technologies, (2) a key LiDAR parameter calibration procedure (including a sensitivity study of the key parameters) is proposed to achieve a desirable traffic sign detection rate, and (3) the reliability and productivity of the proposed method is critically assessed (by quantitatively measuring the detection rate and processing time of the proposed method). Actual data, collected on an interstate highway (I-95) and a local urban road (37th Street in Savannah, Georgia), were used to critically assess the performance. Results show that the proposed method can correctly detect 94.0 and 91.4% of the traffic signs on interstate highways and local urban roads with less than seven false-positive cases. Results also show that when compared to the in-field manual survey test conducted by Georgia DOT, the proposed method can potentially reduce the processing time for sign inventory by approximately 76%. The results demonstrate that the proposed method is promising for establishing a cost-effective traffic sign inventory method for transportation agencies. Future research directions are also recommended.