Driver Response to a Dynamic Speed Feedback Sign on Freeway Exit Ramps Based on Sign Location, Interchange Type, and Time of Day

A series of field evaluations was performed at three freeway interchange ramps in Michigan that possessed significant horizontal curvature to assess the impacts of a dynamic speed feedback sign (DSFS) on driver speed selection and brake response while approaching and entering the ramp curve. A DSFS with a 15?in. full-matrix display was temporarily installed at each of the three exit ramp locations. The sign was programmed to display the same feedback message at each location, which included the speed number for all approaching vehicles, which alternated with a “Slow Down” message for vehicles approaching above 40?mph. The effectiveness of the feedback sign was tested across various sign locations (at the point of curvature versus 350?ft upstream), interchange types (system versus service), time of day (peak versus off-peak), light conditions (daylight versus darkness), and vehicle types (passenger vehicles versus trucks). Compared with the pre-DSFS site condition, the DSFS reduced curve entry speeds and improved brake response at two of the three ramp locations. In general, the greatest beneficial effects on driver behavior were achieved when the DSFS was positioned at the point of curvature, during which curve entry speeds were reduced by approximately 2?mph. These findings were consistent between the system interchanges and service interchanges, and across all vehicle types. The DSFS was also found to be most effective during daytime off-peak periods compared with peak periods and at night. Further evaluation of DSFS at additional ramp locations, and considering an expanded set of conditions, is recommended.

  • Record URL:
  • Availability:
  • Supplemental Notes:
    • This publication is disseminated in the interest of information exchange. MDOT expressly disclaims any liability, of any kind, or for any reason, that might otherwise arise out of any use of this publication or the information or data provided in the publication. MDOT further disclaims any responsibility for typographical errors or accuracy of the information provided or contained within this publication. MDOT makes no warranties or representations whatsoever about the quality, content, completeness, suitability, adequacy, sequence, accuracy, or timeliness of the information and data provided, or that the contents represent standards, specifications, or regulations. © National Academy of Sciences: Transportation Research Board 2021.
  • Authors:
    • Mahmud, Md Shakir
    • Motz, Matthew
    • Holpuch, Travis
    • Hankin, Jordan
    • Ingle, Anthony J
    • Gates, Timothy J
    • Savolainen, Peter T
  • Publication Date: 2021-10


  • English

Media Info

Subject/Index Terms

Filing Info

  • Accession Number: 01774331
  • Record Type: Publication
  • Files: TRIS, TRB, ATRI
  • Created Date: Jun 15 2021 3:37PM