Discussion: View Thread

  • 1.  Performance-Based Geometric Design - TRB Presentation

    Posted 03-30-2017 11:44 AM
    Did anyone attend TRB's webinar on 3/29 regarding performance-based design, which were basically overviews of NCHRP Report 785 and NCHRP Report 839?  I found it interesting and encouraging that context-sensitive and data-driven design may (eventually) find its way into the design guidelines that govern the vast majority of transportation design projects in the United States.  I haven't read the full reports just yet, but thought I'd share a few of my biggest takeaways from the presentation:
    -FHWA design exceptions shouldn't be viewed as a negative, but simply documentation and agreement that the best decision has been made for the context of a project (should make the lawyers happy).
    -The importance of understanding how a facility is used, with a breadth of data AND stakeholder engagement to support that understanding.
    -Introducing the idea that "Rural" and "Urban" are two ends of a spectrum.  Design solutions for communities that do not fit on either end of that spectrum means that neither rural design standards nor urban design standards may apply.   

    Has anyone read these NCHRP Reports?  What do folks think might be the largest hurdles to widespread adoption of these principles?  

    Report 785: Performance-Based Analysis of Geometric Design of Highways and Streets | Blurbs New | Blurbs | Publications 

    Report 839: A Performance-Based Highway Geometric Design Process | Blurbs New | Blurbs | Publications 

    Thanks!

    ------------------------------
    Kensey Russell P.E., M.ASCE
    Project Manager
    HNTB
    Overland Park KS

    ------------------------------


  • 2.  RE: Performance-Based Geometric Design - TRB Presentation

    Posted 04-03-2017 10:50 AM
    Very interesting, although outside of what I have studied.  I did not attend TRB, but I do have a question.  How does the direction appear to be going now in terms of productivity and quality of life?  This is particularly relevant in the global economy.  My biggest concern is in the 85th percentile speed (mentioned in both documents), essentially at +1 standard deviation of the average freeflow speed.  1 standard deviation is the inflection point from the "grouped" typical, or concave down, to concave up on the bell curve.  Setting the speed limit below that increases speed differentials which is a large cause of accidents.  Granted, the higher the speed the more severe the accident, but when traffic "platoons" the number of accidents decreases. 

    Less commuting time means more time at home with family etc., therefore higher quality of life.  It also means higher productivity.  This means America is more competitive in the global market.  Does that make sense?

    ------------------------------
    Stephen Hemphill P.E., M.ASCE
    Semi-Retired
    Rio Rancho NM
    ------------------------------

    Original Message


  • 3.  RE: Performance-Based Geometric Design - TRB Presentation

    Posted 05-11-2017 10:07 AM
    There are a myriad of factors that seem to play into quality of life/productivity as influenced by commute time.  Zoning, land use, education opportunities, crime...the list goes on as it relates to where people live vs. where they work. Since so many of those things are out of the control of a DOT or owner agency, I think DOTs are largely responsive rather than responsible for how their facilities are used.  (I do want to be clear that I'm not saying DOTs aren't responsible for their facilities, just that they have little control over how many people decide to use their system, when they use it, where, etc...)

    I saw the reports as ways to better understand and define the usage of a system in order to formulate the best response to an issue, whether that be a planning issue, a maintenance issue, or an operations/safety issue.  In my experience (limited...I've only been at this 14 years now), productivity and quality of life aren't vocabulary being used.  They may ABSOLUTELY be affected, but traffic operations (congestion, level of service, density, etc), safety, and cost are what show up in pro/con lists of solution alternatives.

    I think relating commute time to global competitiveness makes sense. For a personal anecdote, I recently switched offices to a location about half the distance to my home from what I had been commuting.  I'm not sure if I notice a change in productivity, but I do notice a change in quality of life (a bit more sleep in the mornings, a bit more time to help with dinner in the evenings).

    ------------------------------
    Kensey Russell P.E., M.ASCE
    Project Manager
    HNTB
    Kansas City MO
    ------------------------------

    Original Message


Related Content