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HCS Facilites - How to correctly input ramp add/drop lanes

Bryan
CH2M
HCS Facilites - How to correctly input ramp add/drop lanes was posted on February 28th, 2017 at 9:24 AM EST
regarding Chapter 10: Freeway Facilities

I have a freeway facility that has several on-ramp add lanes and off-ramp drop lanes. How can I represent these segments in the HCS Facilities? In chapter 13 for this situation, I believe both the ramp and upstream/downstream freeway segments are considered basic freeway segments with a change in number of lanes. In HCS facilities, it doesn't look like you can have two basic freeway segments next to eachother with different volumes to represent the ramp. Since these locations aren't technically a merger and diverge section, I'm not sure how I can correctly model this situation in HCS. Thank you for your help.

Bill Sampson
University of Florida
RE: HCS Facilites - How to correctly input ramp add/drop lanes was posted on February 28th, 2017 at 10:15 AM EST

In HCS, you would code the basic segment downstream of the merge or diverge segment with the added or dropped lane. The software will model this as two basic segments with a different number of lanes and check the capacity of the ramp. Please let me know if I can provide more information at bsampson@ufl.edu.

Bryan
CH2M
RE: HCS Facilites - How to correctly input ramp add/drop lanes was posted on February 28th, 2017 at 1:59 PM EST

Thank you Bill, In the HCS Facilities I can input two basic freeway segments together with different number of lanes, but I can’t modify the demand for the downstream basic segment (to account for the change in volume for the ramp). From what I understand, the Facilities analysis in HCS 2010 and HCS7 only allows demand changes for the initial segment & downstream diverge/merge segments. Let me know if there’s a way to correctly analyze this scenario using facilities. Thank you very much for your time.

Bill Sampson
University of Florida
RE: HCS Facilites - How to correctly input ramp add/drop lanes was posted on February 28th, 2017 at 3:00 PM EST

You would code this as a merge or diverge to be able to account for the demands, but it will be analyzed as basic segments when the downstream number of lanes is greater (merge/add) or fewer (diverge/drop). I hope this helps.

Bryan
CH2M
RE: HCS Facilites - How to correctly input ramp add/drop lanes was posted on February 28th, 2017 at 3:44 PM EST

Ok, this makes sense. Basically, I would just code this as a typical merge or diverge segment, but the downstream basic freeway segment would have a different number of lanes to account for the add/drop. Thanks again for the help.

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