For some years, most skid measurement systems have used a watering nozzle of the divergent type, which has been known as the Penn State University (PSU) design. Due to the divergent nature of the PSU nozzle, it has been difficult, if not impossible, to adjust the water flow rate from the nozzle such that it will satisfy the ASTM Standard E-274-77 for pavement wetting at all speeds. In particular, if the water flow rate is adjusted properly at 40 mph it will be out of specifications at 20 and/or 60 mph. The Ohio State University (OSU) Engineering Experiment Station has developed a working model of a non-divergent nozzle from a previous concept by the State of Virginia. This nozzle was compared to the PSU nozzle for accuracy, precision, and ease of calibration to the ASTM-E-274-77 Standards. It was found that there were no significant differences in the measured SN accuracy and precision at 20 and 40 mph. However, at 60 mph, the SN measurement using the PSU nozzle averaged more than one over those obtained when using the OSU nozzle. This significant difference does indicate the effect of flaring out the water trace by the divergent nozzle and thus placing less than normal water thickness ahead of the test tire. The adjustment of water flow rate of the OSU nozzle was easily accomplished at 20, 40, and 60 mph. /FHWA/

  • Corporate Authors:

    Texas Transportation Institute

    Texas A&M University System, 1600 E Lamar Boulevard
    Arlington, TX  United States  76011
  • Authors:
    • Stocker, A J
    • Albert, J W
  • Publication Date: 1977-8

Media Info

  • Pagination: 70 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00179518
  • Record Type: Publication
  • Source Agency: Federal Highway Administration
  • Report/Paper Numbers: FHWA-RD-78-503 Final Rpt., FCP 31H8-254
  • Files: TRIS, USDOT
  • Created Date: Aug 27 1978 12:00AM