One segment of a six-lane urban freeway (three lanes in each direction) is located at 6% upgrade that is 1.0 mi long with 11-ft lanes, obstructions 2 ft from the right edge of the traveled pavement, and ten ramps within three miles upstream and three miles downstream of the midpoint of the analysis segment. A directional weekday peak-hour volume of 3200 vehicles is observed, with 900 vehicles arriving in the most congested 15-min period. If the traffic stream has 15% single-unit trucks and 15% tractor-trailer trucks, determine the level of service.