Purple dots phase II.
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Purple dots phase II.

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    • Alternative Title:
      Maryland Transportation Authority experimental traffic control device testing at Maryland toll plazas : FHWA experimentation #3-181 (ex)-purple dot markings for E-ZPass® lanes, June, 2012
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    • Abstract:
      On behalf of the Maryland Transportation Authority (MDTA), Kittelson & Associates, Inc.

      (KAI) is conducting an evaluation of an experimental traffic control device at a Maryland toll

      plaza. This report summarizes our findings for the evaluation of the purple dot pavement

      marking treatment. The purple dots were installed on the northbound Fort McHenry Toll

      Plaza approach in Baltimore, Maryland in June 2011. They were installed for three dedicated

      E-ZPass® lanes (Lanes 3, 6, and 10) as shown in Figure 4 in the main section of this report.

      The goal of applying the purple dots is to improve toll plaza operations and safety between

      the tunnel mouth and toll plaza by reducing conflicts created by lane changes and weaving

      just prior to the plaza. Additionally, the purple dots are intended to improve wayfinding for

      E-ZPass® customers

      This is the second time purple dots have been installed on the northbound Fort McHenry

      Toll Plaza approach. Under the Phase I experiment, purple dots were installed in November

      2005, and removed several years later when a portion of the toll plaza was rebuilt and the

      roadway was resurfaced. The results of the Phase I experiment are documented in an MDTA

      Report prepared by KAI dated May 11, 2007 (Ref. 1). In Phase I, the purple dots were generally

      found to reduce lane changing and increase utilization of the E-ZPass®ONLY lanes on

      the right side of the toll plaza.

      This report provides the results of the current, Phase II experiment, as well as analysis of

      Phase I crash data not available at the time the Phase I report was prepared. The Phase II

      experiment was conducted in response to the Federal Highway Administration’s (FHWA)

      comments on the Phase I experiment. At this time, the Phase II purple dots remain in place

      at the Fort McHenry Toll Plaza. FHWA granted approval for experimental use of the dots

      through July 1, 2012.

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