Low-cost Ride Quality Characterizations for Transit Systems

Practitioners use the term ride quality to indicate the degree to which a vehicle protects its occupants from factors that decrease ride comfort. Hence, factors that affect ride quality are numerous. The road impact factors (RIP) are uneven road surfaces and roadway anomalies such as potholes, cracks, and utility covers. The driver impact factors (DIP) are driving behaviors such as abrupt braking, rapid acceleration, weaving, and speeding around curves. RIF and DIF can produce motions and noises that cause rider discomfort. The vehicle impact factors (VIF) affect how riders perceive those disturbances. VIF depends on vehicle suspension and handling characteristics, furniture design, interior aesthetics, and other in­vehicle features. Together, these factors result in the ride quality experienced. Highway agencies narrow the definition of ride quality to the RIF and use it as a key indicator of pavement performance (Bridgelall 2014). Manufacturers design suspension systems to attenuate vibrations at frequencies that could cause human discomfort or affect handling safety. Humans are most sensitive to vibrations between 4 and 8 Hertz (Griffin 1990). Hence, nearly all suspension systems attenuate vibrations in that frequency range (Jazar 2008). However, variations in road roughness, driver behaviors, vehicle handling, and suspension design could result in peak vibration levels that induce significant levels of discomfort for some riders. Studies have established that there is a strong linkage between ridership and the perception of service quality in terms of comfort (Benjamin and Price 2006). An old study found that the subjective rating of ride comfort was highly correlated to the frequency and level of vibrations experienced (Park 1976). Since then, relatively few studies characterize ride quality or its importance for transit bus riders. One study (Peterson and Molloy 2007) found that poor ride quality was a major issue of customer concern. Poor ride quality could be a significant deterrent for transit riders but the level of significance is unknown. Furthermore, the degree to which perceived ride quality correlates with the individual factors that causes roughness is unknown. This research will develop a low-cost approach to measure the transit ride quality (TRQ). The methods will include developing the theoretical foundation to characterize the performance of the TRQ measure. The case studies will produce TRQ-indices for at least two transit routes of distinctly different levels of roughness. A survey of the riders on those routes will reveal the relationship between subjective perceptions of roughness and the objective levels measured. The survey will also reveal any influences from the actual roughness level experienced to the stated level of its importance. Agencies will benefit from the research products by utilizing the low­cost tool to study ride quality throughout their service area. Practitioners will have the ability to relate objective measures of ride quality to factors that could potentially affect ridership. The new method of ride quality characterization will provide an estimate of the relative contributions from road impact and driver impact factors.

  • Supplemental Notes:
    • The National Center for Transit Research (NCTR) is a Tier 1 University Transportation Center

Language

  • English

Project

  • Status: Active
  • Funding: $101708
  • Contract Numbers:

    DTRT12-G-UTC22

    79060-02-A

  • Sponsor Organizations:

    National Center for Transit Research

    University of South Florida
    4202 East Fowler Avenue, CUT 100
    Tampa, FL  United States  33620

    Office of the Assistant Secretary for Research and Technology

    University Transportation Centers Program
    Department of Transportation
    Washington, DC  United States  20590
  • Managing Organizations:

    National Center for Transit Research

    University of South Florida
    4202 East Fowler Avenue, CUT 100
    Tampa, FL  United States  33620
  • Project Managers:

    Volinski, Joel

  • Principal Investigators:

    Bridgelall, Raj

  • Start Date: 20150701
  • Expected Completion Date: 0
  • Actual Completion Date: 0

Subject/Index Terms

Filing Info

  • Accession Number: 01615069
  • Record Type: Research project
  • Source Agency: National Center for Transit Research
  • Contract Numbers: DTRT12-G-UTC22, 79060-02-A
  • Files: UTC, RiP
  • Created Date: Oct 26 2016 12:28PM