a six lane freeway (three lanes in each direction) is located on rolling terrain and has 11-ft lanes and right-shoulder lateral clearance of 4 ft. there are four ramps within three miles upstream and three miles downstream of the segment midpoint. a weekday directional peak-hour volume of 1600 vehicles is observed, with 600 arriving in the most congested 15 min period. if los c or better is desired, determine the maximum number of heavy vehicles that can be present in the peak-hour traffic stream. assume familiar users.