No abstract

The Federal Highway Administration (FHWA) requires each state in the United States to report the International Roughness Indices (IRI) of their road network in the annual Highway Performance Monitoring System (HPMS). The reported IRI for road segments are compared to the national standards developed by the FHWA based on national data. Deviations from the national standards are used to identify road segments that need to be included in repair or maintenance programs. The FHWA IRI thresholds for all road classes range between 170 in/mi and 96 in/mi for "acceptable" pavements, and 95 in/mi or less for "good" pavements. The use of the IRI for identifying sections of highways for repair and rehabilitation has been under review in several states. There is the concern that the national values of the IRI often do not reflect the ride smoothness perceived by citizens in the specific jurisdictions. This research obtained the ride quality ratings of residents of a dense urban area (Washington, DC) and correlated those with the IRI values for selected road segments. This research presents the IRI thresholds developed for the urban area based on the regression models obtained and the standard IRI thresholds for newly constructed pavement.

No abstract

The Manual on Uniform Traffic Control Devices (MUTCD) states that Countdown Pedestrian Signals (CPS) shall only be displayed during the clearance interval (FLASHING DON'T WALK -FDW) of pedestrian signals. The purpose of the CPS display is to inform pedestrians of the remaining time for crossing a road controlled by the signal, to discourage them from starting when there is insufficient time for complete crossing, and to inform those who are already on the way of the remaining time before the beginning of the DON'T WALK (DW) interval. The general literature on CPS is conclusive that CPS is better understood than the conventional pedestrian signals. In the District of Columbia the CPS display starts at the onset of the Steady WALK (SW) interval and continues through the FDW interval. It is not certain whether this CPS display has any advantage over the standard display as prescribed by the MUTCD. In this research a comparative field study of both types of countdown displays at twenty-five (25) intersections in the District of Columbia was conducted in addition to an attitudinal survey to gauge the public's preference of the type of display. The results of the evaluation showed that at the majority of the intersections studied, there were no statistically significant differences in pedestrian crossing behaviors (using 5% significance level) due to the type of CPS display. The attitudinal survey results showed that the majority of pedestrians (~86%) and drivers (~83%) prefer CPS display which starts at the onset of the SW.

This study aimed to evaluate the growth performance and Kleiber ratio and to determine the growth curve of Dorper x Tumele sheep under a smallholder management system. Growth and efficiency-related traits were analyzed by using the GLM procedure of SAS. Gompertz, Logistics, Brody, Monomolecular, and Negative exponential models were used to determine the growth curve, and growth curve parameters were estimated via the NLIN procedure of SAS. The overall least-squares means of the birth weight, weaning weight, six-month weight, and yearling weight were 3.29, 13.7, 17.3, and 23.4 kg, respectively. Dorper x Tumele lambs grew faster during the pre-weaning period (115.3±1.19 g day -1) than during the post-weaning periods (44.1±1.26 g day -1 to 33.5±1.13 g day -1). Likewise, a higher Kleiber ratio was observed during the pre-weaning age (16.1±0.08 g/day/kg 0.75) than during post-weaning periods (5.08±0.13 g/day/kg 0.75 to 3.10±0.09 g/day/kg 0.75). Brody, a model without an inflection point was the best-fitted growth function for Dorper x Tumele sheep under a smallholder management system. The highest and lowest asymptotic weight was observed for Brody (23.8±0.22 kg) and Logistics (20.7±0.11 kg) models, respectively. The maturation rate ranged between 0.21 (Brody) and 0.66 (Logistics). Based on the Brody model, the correlation between asymptotic weight and maturity rate was -0.92. The growth parameter estimate in this study indicates that Dorper x indigenous sheep had a better speed to achieve mature weight and the early mature crossbred sheep are less likely to exhibit high adult weight. The rapid growth of crossbred sheep during the early period can provide more profit to the farmer by reducing the cost of sheep production inputs. Therefore, crossing Tumele with Dorper sheep and integrating with improved management would be suggested to improve productivity and profit from sheep production.