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Project Manager

Ytve Guerrera
HNTB
Project Manager was posted on January 11th, 2019 at 3:06 PM EST
regarding Chapter 13: Freeway Merge and Diverge Segments

Exhibit 13-4 shows the typical geometry of a two-lane on-ramp. In this figure the combined length of LA1 and LA2 is less than the influence area of the on-ramp (1,500 ft). I have a situation in which the end of the second acceleration lane goes beyond the 1,500 ft. I am wondering how this should be modeled in HCS. Should LA2 be 1,500-LA1?

Bill Sampson
University of Florida
RE: Project Manager was posted on January 11th, 2019 at 3:13 PM EST

Yes, that is likely the best approach. HCM Page 14-31 defines this maximum length to be 1500 feet: "Component lengths are as illustrated in Exhibit 14-16. Some two-lane on ramps may have acceleration lanes that are longer than the 1,500 ft specified in Exhibit 14-16. In these cases, the acceleration lane length used for calculation should be set to 1,500 ft, since the methodology is not calibrated for greater lengths." I hope this helps. lengths.

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