Existing geometric design guidance related to interchange ramp spacing in the Texas Roadway Design Manual and the AASHTOs A Policy on Geometric Design of Highways and Streets (Green Book) is not speed-dependent even though intuition indicates spacing and speed are related. Understanding the relationship between interchange ramp spacing, speed, and freeway operations is important, especially in developing potential design values for higher speeds (e.g., 85 to 100 mph). The objectives of this project were to: (1) investigate relationships between weaving length, speed, and overall vehicle operations on Texas freeways and (2) propose updates to current Texas Department of Transportation guidance on recommended distances between ramps. Within the research tasks several methods were utilized to assist in developing guidance on ramp spacing lengths. The methods or resources used to generate potential lengths included: guidance provided in Design Manual for Roads and Bridges published by the Highways Agency in England, minimum deceleration and acceleration length for freeway conditions, decision sight distance, sign spacing needs, NCHRP project 3-75 findings, findings from field studies at seven study sites, findings from simulation conducted as part of this research, and safety relationships identified in the literature. Suggested ramp spacings were developed for the entrance ramp to exit ramp and exit ramp to exit ramp conditions.


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    Titel :

    Guidelines for Spacing Between Freeway Ramps


    Beteiligte:
    K. Fitzpatrick (Autor:in) / R. J. Porter (Autor:in) / G. Pesti (Autor:in) / C. L. Chu (Autor:in) / E. S. Park (Autor:in)

    Erscheinungsdatum :

    2010


    Format / Umfang :

    118 pages


    Medientyp :

    Report


    Format :

    Keine Angabe


    Sprache :

    Englisch




    Guidelines for Spacing between Freeway Ramps

    Fitzpatrick, Kay / Porter, Richard J. / Pesti, Geza et al. | Transportation Research Record | 2011



    Urban Freeway On-Ramps

    Yi, Hanwen / Mulinazzi, Thomas E. | Transportation Research Record | 2007


    Microscopic Safety Evaluation and Prediction for Freeway-to-Freeway Interchange Ramps

    Wang, Ling / Abdel-Aty, Mohamed | Transportation Research Record | 2016


    Effects of Off-Ramps on Freeway Operation

    W. E. Tipton / J. D. Carvell / C. Pinnell | NTIS | 1965