Showing papers by "California Department of Transportation published in 2017"

DSRC Versus 4G-LTE For Connected Vehicle Applications: A Study on Field Experiments of Vehicular Communication Performance

Abstract: Dedicated short-range communication (DSRC) and 4G-LTE are two widely used candidate schemes for Connected Vehicle (CV) applications. It is thus of great necessity to compare these two most viable communication standards and clarify which one can meet the requirements of most V2X scenarios with respect to road safety, traffic efficiency, and infotainment. To the best of our knowledge, almost all the existing studies on comparing the feasibility of DRSC or LTE in V2X applications use software-based simulations, which may not represent realistic constraints. In this paper, a Connected Vehicle test-bed is established, which integrates the DSRC roadside units, 4G-LTE cellular communication stations, and vehicular on-board terminals. Three Connected Vehicle application scenarios are set as Collision Avoidance, Traffic Text Message Broadcast, and Multimedia File Download, respectively. A software tool is developed to record GPS positions/velocities of the test vehicles and record certain wireless communication performance indicators. The experiments have been carried out under different conditions. According to our results, 4G-LTE is more preferred for the nonsafety applications, such as traffic information transmission, file download, or Internet accessing, which does not necessarily require the high-speed real-time communication, while for the safety applications, such as Collision Avoidance or electronic traffic sign, DSRC outperforms the 4G-LTE.

Empirical Terrain-Based Topographic Modification Factors for Use in Ground Motion Prediction

Abstract: We develop a model to predict topographic effects on ground motions using the NGA-West2 data set. Topography at a site is quantified using three parameters: smoothed curvature, smoothed slope, and ...

Leg Loss and Fitness in Female Green Lynx Spiders Peucetia viridans (Araneae: Oxyopidae)

Abstract: The relationship between the extent of leg loss and female fitness was investigated in the green lynx spider Peucetia viridans (Hentz, 1832). Adult females and their egg sacs were collected at nine sites in southern California and three measures of bodily characteristics (carapace width, weight, residual index) and three measures of reproductive performance (egg sac weight, egg number, mean sac weight per young) were determined for each spider. Of the 344 spiders sampled, 17.1% were missing one or more legs, with the frequency of leg loss showing no significant differences with respect to the eight limb positions or the four limb pairs among spiders missing one leg. While female size did not differ among leg-loss groups, females which were intact or which had lost one leg were generally heavier and in better body condition than females which had lost two or three legs. Such eight- and seven-legged females also produced heavier egg sacs and more eggs than six-legged females. These findings do not support Guffey's (1999) prediction that female arachnids which lose two legs experience minimal costs, but they are consistent with Brueseke et al. (2001)'s suggestion that reproductive output might be reduced for female spiders which have lost legs. Why females missing three or more legs did not exhibit a comparable, if not more severe, reduction in egg sac weight and egg number than six-legged females is unknown, though it may be related to the small size of this group (8) and peculiarities of the few spiders in it.

Development of a Universal Cracking Amount Model for Fatigue and Reflective Cracking of Asphalt Pavements

Abstract: This paper reviewed mechanistic-empirical (ME) design and analysis frameworks and identified a weak link: a cracking amount model connecting pavement damage (predicted from mechanistic-empi...