Evaluation of the Impact of Presence Lighting and Digital Speed Limit Trailers on Interstate Speeds in Indiana Work Zones

Work zone safety continues to be one of the important focus areas for transportation agencies. Previous studies have identified that vehicle speed and lighting conditions are significant risk factors impacting work zone safety. This study evaluated the impact of the use of presence lighting and digital speed limit trailers on nighttime motorist speeds using commercially available connected vehicle speed data. Geospatial analysis was conducted on over 500,000 connected vehicle records to linear reference nearly 18,000 records from 195 unique trajectories to study section during the study period of 2 days. Results showed that median speeds reduced by 4 to 13 mph from 11PM to 7AM during the deployment of presence lighting and speed limit trailers compared to base conditions. A Kolmogorov-Smirnov (KS) statistical test comparing 105 vehicles traveling through the construction zone with presence lighting and speed limit trailers with a group of 90 vehicles during base condition indicated the speeds during the deployment of presence lighting and speed limit trailers were lower than the base condition. Also, increased compliance with the 55 mph speed limit was observed when the presence lighting and digital speed limit trailers were deployed. However, there were two hours (3AM to 5AM) where speeds increased by 0 - 4 mph, perhaps due to the low volume at that hour. The encouraging results support the further deployment of presence lighting and speed limit trailers in nighttime construction zones for reducing vehicle speeds. Those future deployments should be monitored with connected vehicle speeds to collect additional data to broaden the evaluation of these speed mitigation techniques over a diverse set of construction zone activities.

Investigating the impacts of urban speed limit reduction through microscopic traffic simulation

Road traffic congestion has become an everyday phenomenon in today's cities all around the world.The reason is clear:at peak hours,the road network operates at full capacity.In this way,growing traffic demand cannot be satisfied,not even with traffic-responsive signal plans.The external impacts of traffic congestion come with a serious socio-economic cost:air pollution,increased travel times and fuel consumption,stress,as well as higher risk of accidents.To tackle these problems,a number of European cities have implemented reduced speed limit measures.Similarly,a general urban speed limit measure is in preparatory phase in Budapest,Hungary.In this context,a complex preliminary impact assessment is needed using a simulated environment.Two typical network parts of Budapest were analyzed with microscopic traffic simulations.The results revealed that speed limits can affect traffic differently in diverse network types indicating that thorough examination and preparation works are needed prior to the introduction of speed limit reduction.

Size Reduction of Tunable Micromachined Filters for High Speed Operations

The size reduction of tunable micromachined filters is carried out for high-speed wavelength tuning. We fabricated micromachined filters having a miniature structure with an air gap of 300 run and a short cantilever of 45 urn, exhibiting fast response of below 3 us.

WIND SPEED DISTRIBUTION REGULARITY AND WIND REDUCTION EFFECT OF SHELTER NET

Wind speed distribution regularities in a shelter mesh (S. M.) have been deduced from the wind speed distribution in the sheltered area of a single shelter beh (S. B.).The components of a wind vector in a mesh follow the error function distribution model or the logarithmic model of 2-variable power function.The wind vector itself follows the vector composition model of these models.We can calculate the wind speed distribution and wind reduction effect of a mesh under the conditions of any shelter-belt characteristics, any size and shape of a mesh and any wind inclination angle with this model. The results of our field model experiment are in better agreement with the theoretically calculated results.