No abstract

Passing on rural two-lane highways is one of the most important driving tasks. More than 28000 vehicles were observed and the passing maneuvers were recorded of 10 two-lane highways in northern Iraq during June and July months of 2005. It was found that the number of passing maneuver increase as the flow rate for both directions increase up to 1500 veh/hr flow rate. The passing maneuvers decreases with the increase in flow rate. The increase in flow rate causes an increase in demand of passing and decrease in passing supply. Volume of around 212 veh/hr gives a balance between demand of passing and passing supply.

Headway is the time interval between passages of successive vehicles past a point on the highway. More than 8000 car headways were observed in 10 level and rolling terrain two-lane highways in northern Iraq to find the critical headway and headway distribution and modeling for these highways. It is found that the critical headways are ranges between 2.5 to 4.0 seconds with a suitable critical headway of 3.2 second. The best headway model consists of composite model, for free vehicles it is a shifted negative exponential distribution, while for constrained vehicles it is a lognormal distribution.

Abstract. The present study was conducted on Reclaimed Asphalt Pavement (RAP) to assess the optimum blending ratio with new material for possible use in road construction and maintenance. It was planned to use reclaimed materials from one of the streets of the city of Mosul in Iraq, after mixing with the new material (asphalt grade (50-60), filler and aggregate) for binder course construction. Optimum asphalt content was obtained using Marshall Method through the preparation of a mixture of new material and uses this value in the preparation of recycled mixtures. Five percentages of RAP, namely, (0%, 20%, 30%, 50% and 100%) have been implemented. A total of (155 Marshall, 75 beam) specimens, and 10 slab samples were prepared in this study. Many tests were used to assist the performance of the HMA samples, these tests includes: Marshall characteristics, indirect tensile strength at 25˚C, 60˚C, flexural strength at 0˚C, -10˚C, cohesion resistance, static creep at 25˚C, 40˚C, fatigue resistance and rutting resistance. Results indicate that using RAP up to 50% is feasible, and it can improve asphalt mixture properties and its performance, while 30% is considered the ideal ratio since it showed better performance in all tests except for the fatigue where shorter fatigue life was observed.

In this study, ten pedestrian crossing spots located in Dohuk City suburban area were selected to make analysis and evaluation to the behavior of the people crossing the main streets, and walking on sidewalks according to their genders. Data was collected using double video cameras fixed on selected points to observe pedestrian movements along crossings and sidewalks, their interaction with drivers, and vehicles conflicting them. Data compiled was classified and presented to measure numbers of moving vehicles, people, vehicle gaps, space, pedestrian unit flow, speeds of both pedestrians and vehicles passing the crossing lines on suburban midblock. Data was presented using Dohuk City GIS up-to-date map taken from the city Municipality Directorate. Data analysis was implemented, and different empirical models were chosen to study the different interactions and effects of human, geometric, and vehicular traffic parameters on the behavior of pedestrians crossing, and walking on crosswalks and sidewalks respectively. Results show that in crosswalks, pedestrian flow with their speeds were polynomial in nature, while unit flow and speed relationships with density were linearly correlated. The relation between unit flow and their speed (for both male and female) on suburban sidewalks is Polynomial 2nd degree, and the optimum walking speed obtained is 1.16 and 1.0 m/sec for male and female respectively, with minimum walking speed for females are lower than male but the maximum walking speed is similar.