a six-lane urban freeway (3 lanes per direction) is on rolling terrain with 10-ft lanes, obstructions 5 ft from the right edge of the traveled pavement and 8 ramps within 3 miles upstream and 3 miles downstream of the midpoints of the analysis segment. a directional weekday peak-hour volume of 2800 vehicles is observed with 760 vehicles arriving in the most congested 15-min period. the traffic stream has 7% single unit trucks and 3% tractor-trailer trucks. a. determine the density and the los. b. if instead of rolling terrain, the freeway segment has an incline of 4.5% for a distance longer than 2 miles, determine the density and los