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Merge two one lane highways

Kerstin Rupp
Merge two one lane highways was posted on June 21st, 2018 at 6:36 AM EDT
regarding Chapter 13: Freeway Merge and Diverge Segments

To whom it may concern, I have the situation that I have two 1 lane state highways immediately merge into 1 lane. What adjustment factor would I use for a 2 lane Freeway instead of 4 lane Freeway? Or alternatively is there a simpe calculation that I could use??

PHF 0.95% 80km/hr on both state highway lanes

SH1 1029 pcu/hr, SH2 730 pcu/hr - merging like a zip into 1 combined lane.


Bill Sampson
University of Florida
RE: Merge two one lane highways was posted on June 21st, 2018 at 7:16 AM EDT

Hi Kerstin,

Your suggestion about using a merge analysis onto a one-lane freeway is described in HCM6 Exhibit 14-22(c) and could apply in your case if the roadway is similar to a freeway in design and speed. I have seen this used for the merging of a one-lane frontage road to a one-lane freeway on-ramp.

Hope this helps, Bill

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