The popularity of bicycles in North America is growing. As the popularity of bicycles has increased, so has the physical network of separate bicycle facilities and designated bicycle lanes in many locations. As a consequence of this growth, there is a demand for more information about bicycle operations on these facilities. Unfortunately, the state of knowledge regarding bicycle operations in the United States currently lags far behind that of motor vehicles and pedestrians. The international research that has been conducted to date regarding bicycle operations on uninterrupted facilities is thoroughly reviewed, and recommended procedures for the operational analysis of uninterrupted bicycle facilities are outlined. The recommended procedures are based on the concept of “frequencies of events” involving a bicyclist and other bicyclists or facility users. Events are defined as bicycle maneuvers required by a bicyclist on a facility, including passings (same-direction encounters) and meetings (opposite-direction encounters). The frequency of events for an uninterrupted bicycle facility is related to the service volumes of bicycles using or projected to be using the facility and does not have to be observed directly. The proposed procedures are, therefore, recommended based not only on their theoretical substance but also on their ease of use by practitioners.

Work zone capacity values for rural and urban freeways without continuous frontage roads were defined and determined. Data were collected using Nu-Metrics counters and classifiers at 24 work zones in North Carolina. The research included analysis of speed-flow behavior, evaluation of work zone sites based on lane configuration and site location, and determination of the location within the work zone where capacity is lowest. It was shown that the intensity of work activity and the type of study site (rural or urban) strongly affected work zone capacity. The data suggested that the location where capacity is reached is also variable based on the intensity of work. For heavy work in a two-lane to one-lane work zone configuration, the capacity values proposed at the active work area are approximately 1,200 vehicles per hour per lane for rural sites and 1,500 vehicles per hour per lane for urban sites. It is recommended that two distinct volumes be used when queue behavior in a freeway work zone is analyzed. The collapse from uninterrupted flow (designated work zone capacity) and the lower queue-discharge volume both should be considered.

Signalized intersections on high-volume arterials are often congested during peak periods, causing a decrease in through movement efficiency on the arterial. Much of the vehicle delay incurred at conventional arterial intersections is caused by high left-turn demand. Unconventional intersection designs attempt to reduce intersection delay and travel times by rerouting left turns away from the main intersection. Seven unconventional designs—the quadrant roadway intersection, median U-turn, superstreet median, bowtie, jughandle, split intersection, and continuous flow intersection designs—that could apply to a wide range of standard, four-leg intersections are compared. Previous comparisons of intersection delay and travel time between conventional designs and these unconventional designs have been piecemeal and have largely used hypothetical volumes. Simulation experiments were conducted using turning movement data from seven existing intersections of varying sizes to compare the travel time of conventional and unconventional designs fairly. Optimum cycle lengths were used for each design, and a number of factors were held constant to keep the comparisons fair. Off-peak, peak, and peak-plus-15-percent volume levels were examined. The results from the simulations showed that at each intersection one or more unconventional designs had lower total travel times than the conventional design. Whereas most of the unconventional designs showed improvement in one or more scenarios, the quadrant roadway intersection and the median U-turn designs consistently produced the lowest travel times. When considering the design of high-volume intersections like those tested, engineers should seriously consider quadrant roadway intersection and median U-turn designs where rights-of-way are available.

The objective of this research was to determine the performance characteristics of thermoplastic pavement markings in NC and to create viable degradation models. Additionally, an evaluation of paint pavement marking materials was conducted and models were created for them as well. The resulting models provide pavement marking managers with valuable tools that will allow them to focus limited resources where they are most needed and avoid replacing materials with effective life still remaining in them. Consideration was given to the analysis of the relationships between pavement marking retroreflectivity values and variables such as time, traffic volume, and marking color. Unique to this research is the inclusion of lateral location as a key variable affecting the performance of pavement markings. Another key contribution to pavement marking management from this research was the development and use of level of service increments for describing the status of a given marking at some point in time. Using the tools reported herein an expected service life for thermoplastic and paint pavement markings in NC can be estimated. A key finding of the research is that the markings have a far greater life expectancy than originally expected. Combining our predictive tool with level of service increments provides a holistic infrastructure management approach to pavement markings.

Roundabouts generally provide safety and other advantages. During peak hours, however, even moderate demands on an upstream approach can result in long delays and driver frustration over downstream movements. A metering signal is one way to ensure that all demands at a roundabout are adequately served. A roundabout metering signal regulates flow into the circle from one approach and thereby creates larger gaps in the circle for downstream entrants. Although metering signals have been used successfully around the world, little guidance is available for U.S. designers. The goal of this research was to provide U.S. designers with some guidance on the use of metering signals. The authors developed a simple macroscopic model based on the Highway Capacity Manual, validated it by using a simulation model, and performed exercises with it on a number of demand combinations to see where a meter might help. The macroscopic model should be helpful as a quick screening tool. The results from application of the model provide evidence that a meter may reduce delays compared with those seen in an unmetered roundabout with some demands. Although signalized intersections produced lower delays than did metered or unmetered roundabouts in most cases tested, roundabouts were sometimes better. Analysts should consider more than just peak period delays in deciding on the optimum traffic control at an intersection. If, with the aid of a metering signal for a few peak hours, a roundabout produces slightly higher delay levels during those peak hours than a standard traffic signal, with consideration of its many other benefits, a roundabout could well be the optimum design.