Eric Meyer

EVALUATION OF ORANGE REMOVABLE RUMBLE STRIPS FOR HIGHWAY WORK ZONES

Rumble strips can be effective in alerting drivers to road conditions that merit special attention. The Kansas Department of Transportation (KDOT) requires the deployment of rumble strips on state routes during maintenance work that necessitates the closure of a lane on a two-lane highway. In such a case, a temporary signal is placed at each end of the work zone, and rumble strips are used to alert drivers that they may need to stop. Currently, cold-mix asphalt is used to create the rumble strips. A new product, orange removable rumble strips, promises to reduce significantly the effort required to apply and to remove rumble strips, while improving safety by increased conspicuity. These removable rumble strips were evaluated at a bridge repair site in rural Kansas. Vehicle speeds were recorded with only the standard asphalt rumble strips in place; then the removable rumble strips were installed and more speed data were collected. Installation and removal times also were compared. Strips were easily applied and easily removed. The audible and tactile effects of the strips were weak due to their 3.2-mm (1/8-in.) thickness in comparison with the 12.7 to 19 mm (1/2 to 3/4 in.) thickness of standard asphalt rumble strips. However, the orange removable rumble strips were found to have a significant effect on vehicle speeds, attributable to their high visibility. KDOT plans to conduct another evaluation using a version of the same device that is 20 percent thicker.

CHARACTERIZING AND MODELING OBSERVED LANE-CHANGING BEHAVIOR: LANE-VEHICLE-BASED MICROSCOPIC SIMULATION ON URBAN STREET NETWORK

Key findings are discussed regarding characteristics of lane-changing behavior based on observations of an urban street network. An in-depth exploration of observed lane-changing behavior and its modeling were conducted using vehicle trajectory data extracted from video observations using VEVID, a software package developed by the authors, integrated with a video-capture system. As a result, rules for modeling lane-changing behavior are proposed with respect to various types of lane changes. A lane-changing model consists of three components: a decision model, a condition model, and a maneuver model. Drivers’ decisions to change lanes depend on travel maneuver plans, the current lane type (i.e., the relationship between the current lane and the driver’s planned route), and traffic conditions in the current and adjacent lanes. A lane-changing condition model is the description of acceptable conditions for different types of lane changes. A lane-changing maneuver model describes a vehicle’s speed and duration when a certain type of lane change occurs. All of these models are established in a heuristic structure.

Application of Optical Speed Bars to Highway Work Zones

The proximity of workers and traffic makes safety a high priority in highway work zones. The occurrence and severity of accidents is related to vehicle speeds and speed variations. The use of optical speed bars to reduce speeds and speed variations in highway work zones is examined. Previous applications of this traffic control device are considered with respect to design parameters such as length of pattern, number of stripes, and the sequence of spacing between bars. A general design was developed to test the effect of the pattern on speed, the mechanism through which the effect occurs, and the usefulness of the technique to work zones (previous applications have been predominantly at the approach to intersections). Because the application of multiple-pattern designs is impractical, simulations of various designs were developed to obtain subjective evaluations of the relative effectiveness of the various alternatives. Based on the review of previous applications and the subjective evaluations, a pattern design was developed. The design process is delineated and the resulting design described. Also described are adaptations that were made to previous designs specifically for the application of the technique to highway work zones. Finally, a test project to measure the effect of the technique on traffic is described.

TECHNOLOGICAL ADVANCEMENTS IN HAZARDOUS MATERIALS EVACUATION PLANNING

The development and implementation of a methodology by which evacuation planners can assess the sufficiency of their current evacuation plan, identify inadequacies, and define and evaluate potential improvement strategies are discussed. Such goals are accomplished through innovative uses of information technology and the development of a modeling environment that builds on previous work by introducing more representative and efficient algorithms. The new evacuation planning methodology is subsequently applied to a fixed facility incident scenario to demonstrate its applicability to present practice. In this context, several important conclusions are reached, illustrating the importance of having this type of decision-support tool available. Advancements made to the state of the art are assessed and further research needs in this critical and emerging field are identified.

Generating Vehicle-Specific Speed Profiles from Automatic Traffic Recorders

Conventional speed studies can be used to evaluate the effects of various aspects of highway design and traffic control on the speeds at which drivers choose to travel. Typical parameters examined are mean speeds, 85th percentile speeds, and speed variation indicated by standard deviation or mode. More detailed studies have been conducted by using manual techniques and specialized equipment to generate vehicle-specific speed profiles. A useful technique, called vehicle tracing, allows data from common automatic traffic recorders to be used to generate such profiles automatically. The availability of these profiles opens new avenues of analysis that ultimately promote safer highway design and traffic-control practices. This technique is discussed, and its benefits are illustrated through a case study—an evaluation of optical speed bars, an innovative technique for slowing traffic in highway work zones.

Interpreting Cellular Coverage for Transportation Applications

The process was developed for collecting and analyzing cellular coverage data by applying the results of analysis to analog cellular coverage in the state of Kansas. The type of analysis that is appropriate depends on the purpose for which the information is to be used. Two types of analyses were examined—fixed coverage and mobile coverage. Fixed coverage analysis is needed for such functions as automatic collision notification in which any individual cellular connection can occur from a fixed location. The study showed that the fixed cellular coverage of the Kansas state highway system was good. Only 0.4% of the highway by length had inadequate signal strength for using a 3-W phone (a typical car phone) and 1.7% for using a 0.6-W phone (a typical handheld unit). In contrast, the mobile coverage analysis identified numerous areas where a call from a moving vehicle would be severely limited in duration. This type of analysis is needed for applications such as communications for emergency medical services, for which a vehicle must sustain continuous communications. For example, more than 9% of the state highways by length cannot sustain a call of 30 min with a 0.6-W phone, and in some areas the percentage is considerably higher. For certain applications, this difference may simply translate to inconvenience, but for other purposes it can be very important. The results of the two types of analyses highlight different characteristics of the coverage footprint; one addresses absolute coverage and the other continuity of coverage. The results of the analysis technique relate more directly to the unique characteristics of wireless communications utilization in transportation applications.