The Manual on Uniform Traffic Control Devices (MUTCD) establishes the basic principles for the design, selection, installation, operation, maintenance, and removal of traffic control devices (TCDs). The MUTCD indicates that some TCDs that are required and some are recommended, depending on the situation. However, most TCDs are not required and the decision to use a given TCD in a given situation is typically made by an engineer (or an individual working under engineering supervision) based on a variety of information. Not all engineers have the same degree of experience in making TCD decisions, and not all engineers that make these decisions have traffic engineering expertise. There are many other factors not addressed by the MUTCD that can lead to differences in the decision-making process. To assist engineers with evaluating these factors, this research developed a decision analysis process to assist engineers with making TCD decisions. The value of this research is the idea that the decision analysis process for TCD can be modeled and analyzed using appropriate factors. The developed factors include need, impact, influence, and cost. The process developed in this research applies two elements to each factor. One element compares the importance of each factor among all the other factors, and the other incorporates the engineer's judgment into the TCD decision. The first element described uses a decision analysis method, analytic hierarchy process, to determine the weights for each factor, or coefficients, as applied generally to a TCD. The second uses a mixture of quantitative and qualitative engineering judgment to determine the degree to which the factor applies to the TCD situation, or situational variable. The output of this process was a utility value that can be compared to a scale and determine the installation value of the device. This process will contribute to more uniform decisions amongst all levels of experience in TCD decision-making. Additional research that could expand on this developed process would include data collection on typical importance values for each factor as applied to a TCD and on decision scales for specific TCD situations. When applying this research, it is important to remember that it is not the intent of this process to remove engineering judgment. This is an important part of the process and should remain as such.

No description available.

Reduced-speed school zones greatly improve the safety of young children commuting to and from school and provide larger gaps in traffic for children to cross the street. The main focus of this study was to determine effective methods for increasing speed compliance in reduced-speed school zones. This objective was accomplished through an in-depth literature review, a public opinion survey of Utah drivers, and an evaluation of the effects of speed monitoring displays (SMDs) in school zones. The main focus of the literature review was to determine how to increase and maintain speed limit compliance within school zones. Information about the following topics with respect to school zones was researched and compiled: traffic control devices, SMDs, law enforcement, and other speed influences. A public survey was developed and implemented to evaluate the feelings and concerns of Utah drivers with respect to school-zone safety and school-zone traffic control devices. The survey was conducted in various locations throughout the state of Utah and proved to be an effective tool. The majority of those surveyed felt there was a need to improve school-zone safety in Utah. An evaluation of SMDs in four school zones throughout the state was performed. The results concluded that the SMDs analyzed in this study proved to increase speed compliance in most cases. In some cases, the SMDs maintained their effectiveness at increasing speed compliance over time; on the other hand, others lost some of their effectiveness over time, possibly due to higher percentages of commuter traffic. For the most part, speed compliance increased as manifested by the decrease in mean speed, standard deviation, 10 mph pace range, and the percentage of vehicles exceeding the 20 mph school-zone speed limit. In summary, the results of this study suggest that a combination of effective traffic control devices, public education, and appropriate law enforcement are all necessary to improve speed-limit compliance in school zones.

The purpose of the following report is to account for and summarize the authority and tasks that municipalities, authorities and contractors have in the implementation of temporary traffic diversions. In addition to this, the cooperation between all actors has also been investigated with the aim of finding out what types of routines and potential tools are used in connection with the work. The implementation of the report is based on a qualitative study, for which relevant people with different tasks have been interviewed or answered questionnaires. Furthermore, governing documents for relevant parties have been studied with the intention of describing the requirements that apply to work adjacent to or on the road. The results have subsequently been compiled in an account of the work parties' tasks, views and suggestions for improvement. In this it appears that the road maintenance authorities have an examinative responsibility and has the authority to approve the work carried out on its behalf. For and in particular all road works, of which the diversion is a part, traffic device plans must also be drawn up and describe solutions for traffic-related problems. These are the tasks of the executing contractor to draft with regard to the requirements of the road maintenance authority. It also appears that the majority of the interviewees consider the cooperation to be satisfactory, but state how interpretation of the governing documents can result in conflicts between the parties. In addition, significant differences for the systems used in the coordination can be noted for each municipality and authority.

The Flashing Yellow Arrow Left Turn signal is quickly becoming prominent in Central Florida as a new method of handling left turns at traffic signals. While the concept of a protected-permitted left turn is not groundbreaking, the departure from the typical display of a five-section signal head is, for this type of operation. The signal head introduced is a four-section head with a flashing yellow arrow between the yellow and green arrows. With this signal head quickly becoming the standard, there is a need to re-evaluate the operational characteristics of the left turning vehicle and advance the knowledge of the significant parameters that may affect the ability for a driver to make a left turn at a signalized intersection. With previous research into the behavioral and operational characteristics of the flashing yellow arrow conducted, there is more information becoming available about the differences between this signal and the previously accepted method of allowing left turns at an intersection. The protected-permitted signal is typically displayed at an intersection with up to two through lanes and generally a protected signal is installed when the number of through lanes increases above two unless specific criteria is met. With the advent of larger arterials and more traffic on the highway networks, the push to operate these intersections at their maximum efficiency has resulted in more of these protected-permitted signals being present at these larger intersections, including the flashing yellow arrow. The core of the research that follows is a comparative analysis of the operation and parameters that affect the left turn movement of the intersection with larger geometry to that of the smaller geometry. The significant parameters of the left turn movement were examined through means of collecting, organizing and analyzing just over 68 hours of field data. This research details the determining of the significant parameters based on the generation of a simulation model of the protected left turn using Synchro, a traffic simulation package, and regression models using field driven data to determine the significant parameters for predicting the number of left turns that can be made in the permitted phase under specific operating conditions. Intuitively, there is an expectation that a larger intersection will not allow for as many permitted lefts as a smaller intersection with all conditions remaining the same. The conclusions drawn from this analysis provide the framework to understanding the similarities and the differences that are encountered when the intersection geometry differs and help to more efficiently manage traffic at signalized intersections. The work of this field promises to enhance the operations of the left turning movement for traffic control devices. With an understanding of the statistical models generated, a broader base of knowledge is gained as to the significant parameters that affect a driver's ability to make the left turn. A discussion of the statistical differences and between the models generated from the small and large geometry intersections is critical to drive further research into standards being developed for the highway transportation network and the treatment of these large signalized intersections. The exploration of specific parameters to predict the number of permitted left turns will yield results as to if there is more to be considered with larger intersections moving forward as they become a standard sight on the roadway network.