Looking at the example ramp for the after scenario, examining both the on and off ramp for the eastern section of the interchange (with the higher volume).
The total volume of the freeway facility including the ramp volume is 1274 with the on and off ramp volumes of 280. The peak hour factor for both the freeway and the ramp were set to 0.95. There were no obstructions on either the freeway or the ramp. The freeway speed was entered as 65 mph and the effective ramp at 45 mph (assuming no geometric requirements for lower speeds). The percent truck for the freeway was set to 8% with 2% RVs and the ramp was 5% and 1% RVs. There were no other ramps entered that would interfere with this ramps operations.
The terrain was entered as rolling.
Running this calculation through the software, the ramp operational characteristics show a density of 16 passenger cars per mile per lane, an operating speed of 57 mph on the freeway and a ramp level of service B.
Running the same calculation for the on ramp to the freeway facility, the only change was the direction of the ramp in the traffic page.
Resulting in a density of 19 passenger cars per mile per lane, operating speed of 58 mph and a ramp level of service B.
This type of analysis should be included for each ramp segment in the interchange. For information on other items shown in the screen shots, please consult the Highway Capacity Manual to answer these additional questions.
Select any of the options to receive more information or click on the back button to return to the HCS analysis page or the site map button to go to the site map.
