Experimenting with Orange Pavement Markings on Indiana Roadways

This session presents the status of experimental orange pavement markings on Indiana roadways. The presentation includes a summary of the MUTCD experimentation request and an evaluation of orange pavement marking types— including tapes and paints with a focus on color and retroreflectivity retention. The effects of driving behavior on the safety of work zones, vehicle lane positioning, and public opinion are also discussed

Utilization of Unmanned System Technology in Transportation Engineering

Drone technology can be very beneficial to transportation engineering by increasing the efficiency of the data collection process and limiting the number of personnel needed, allowing resources to be dedicated to multiple projects simultaneously. However, the technology can be costly. This presentation identifies a cost-effective way to employ drone technology for data collection

Long-Term Effectiveness of Radar Speed Display Signs in a University Environment

Vehicular speeds are of particular interest in areas with a high number of pedestrians due to the fact that 14-percent of all fatal crashes involve pedestrians. This study investigated the effect of a radar speed display sign placed for an extended period of time, at a location frequented by law enforcement on a road segment entering a university campus with a high number of pedestrians and vehicle speed violations. The statistical analysis included a comparison between AM peak, PM peak, and midday speeds collected one year apart. The data suggested that radar speed display signs can remain effective over a long period of time; causing drivers to decelerate when warned of a speeding violation. While other studies have examined long-term impacts of similar technologies, none have included a road entering a University campus. Thus, these findings support that other similar locations entering university campuses could see long-term benefits to stationary radar speed display signs

Identifying the Safety Impact of Signal Coordination Projects along Urban Arterials Using a Meta-analysis Method

The safety impact of changes to roadway operations have been of interests in recent years with the publication of the Highway Safety Manual. One area that is in need of further study is the safety impact of traffic signal coordination projects in urban areas. Specifically, this study seeks to identify the safety benefit from traffic signal coordination projects on major arterial roadways through urban areas using a before and after study with a comparison groups approach and a meta-analysis method. The findings suggest that traffic signal coordination could decrease total crashes by 21 percent, injury crashes by 52 percent and property-damage-only crashes by 21 percent. The results can be utilized by engineering practitioners to estimate the safety benefits for projects that seek to coordinate traffic signals along an urban corridor. Because these projects can both improve the safety of roadways while improving traffic flow, the application of these findings could be broad

The Impact of Traffic Incident Locations on a Metropolitan Evacuation

Modeling emergency evacuations can help engineers, planners, and emergency managers identify the approximate time it would take for evacuees to leave a disaster area. Unfortunately, many evacuation studies do not account for traffic incidents. This study examined the effect of traffic incidents during a no notice emergency evacuation in the eastern St. Louis metropolitan area road network. The roadway network was modeled using traffic micro-simulation software VISSIM, which utilized the expected traffic volumes that were determined by the regional planning agency, and guided by input from the transportation engineers at the Illinois Department of Transportation (IDOT). Because traffic speeds are expected to be low during such a high-volume event, this study considered only minor incidents. Incident locations were selected based on historical data. The results suggest that minor traffic incidents occurring upstream of key bottlenecks created no significant change in delay or evacuation duration. On the contrary, minor traffic incidents downstream of bottlenecks can significantly increase delay; albeit not enough to delay the duration of the entire evacuation by more than 15 minutes. Thus, during no notice emergency evacuations, traffic managers could prioritize available traffic incident management resources accordingly

Planetary systems around close binary stars: the case of the very dusty, Sun-like, spectroscopic binary BD+20 307

Field star BD+20 307 is the dustiest known main sequence star, based on the fraction of its bolometric luminosity, 4%, that is emitted at infrared wavelengths. The particles that carry this large IR luminosity are unusually warm, comparable to the temperature of the zodiacal dust in the solar system, and their existence is likely to be a consequence of a fairly recent collision of large objects such as planets or planetary embryos. Thus, the age of BD+20 307 is potentially of interest in constraining the era of terrestrial planet formation. The present project was initiated with an attempt to derive this age using the Chandra X-ray Observatory to measure the X-ray flux of BD+20 307 in conjunction with extensive photometric and spectroscopic monitoring observations from Fairborn Observatory. However, the recent realization that BD+20 307 is a short period, double-line, spectroscopic binary whose components have very different lithium abundances, vitiates standard methods of age determination. We find the system to be metal-poor; this, combined with its measured lithium abundances, indicates that BD+20 307 may be several to many Gyr old. BD+20 307 affords astronomy a rare peek into a mature planetary system in orbit around a close binary star (because such systems are not amenable to study by the precision radial velocity technique).Comment: accepted for ApJ, December 10, 200

Appropriate inclusion of interactions was needed to avoid bias in multiple imputation

OBJECTIVE: Missing data are a pervasive problem, often leading to bias in complete records analysis (CRA). Multiple imputation (MI) via chained equations is one solution, but its use in the presence of interactions is not straightforward. STUDY DESIGN AND SETTING: We simulated data with outcome Y dependent on binary explanatory variables X and Z and their interaction XZ. Six scenarios were simulated (Y continuous and binary, each with no interaction, a weak and a strong interaction), under five missing data mechanisms. We use directed acyclic graphs to identify when CRA and MI would each be unbiased. We evaluate the performance of CRA, MI without interactions, MI including all interactions, and stratified imputation. We also illustrated these methods using a simple example from the National Child Development Study (NCDS). RESULTS: MI excluding interactions is invalid and resulted in biased estimates and low coverage. When XZ was zero, MI excluding interactions gave unbiased estimates but overcoverage. MI including interactions and stratified MI gave equivalent, valid inference in all cases. In the NCDS example, MI excluding interactions incorrectly concluded there was no evidence for an important interaction. CONCLUSIONS: Epidemiologists carrying out MI should ensure that their imputation model(s) are compatible with their analysis model