Work Zone Speed Management (2015) / Chapter Skim
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Pages 35-48
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35 chapter four ENGINEERING TECHNIQUES INTRODUCTION How a work zone is designed and organized can help create an environment that encourages drivers to select an appropriate speed. Typically, this involves providing visual or tactile cues (in addition to speed limit signs)
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36 NCHRP Report 476 cautions against this situation (Bryden and Mace 2002) : It is often necessary to use two or more longitudinal rows of channelizing devices to define both sides of a travel lane or for exit and entrance lanes.
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37 sure with traffic merging into the left lane followed by a lane shift to the right, as shown in Figure 18. According to Lorscheider and Dixon (1995)
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38 ent situations, including two that are similar to the Iowa Weave (Direccion General de Carreteras 1997)
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39 (a) FIGURE 20 Two-lane and three-lane chicane designs from a work zone design manual published by Spain's Ministry of Public Works (speeds in kilometers/hour and distances in meters)
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40 (b) FIGURE 20 (Continued )
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41 mean speed by 6.9 km/h (4.3 mph) and the 85th percentile speeds by 9.5 km/h (5.9 mph)
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42 The average speed of all vehicles deceased by 1 mph; nevertheless, the number of adjacent lane encroachments increased by 8.8%. • A Kansas study evaluated the effect of portable plastic rumble strips (PPRS)
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43 Barriers, LLC (only the MBT-1 was in commercial production)
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44 FIGURE 25 Manitoba gateway assembly for freeway applications (approaching work zone) (Manitoba Infrastructure and Transportation 2013)
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45 on a visual simulation suggested that a chevron pattern was perceived as being more effective. • Within the study area three areas were identified, a "leading pattern" with uniformly spaced bars, a "primary pattern" of converging bars, and a "work zone pattern" with intermittent uniformly spaced bars.
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46 Manual stipulates that the skid resistance of the bars should not be less than 55 (DfT 2003)
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47 SEQUENTIAL AND SYNCHRONIZED WARNING LIGHTS The illusion of motion can be created when discrete stationary lights are flashed sequentially. A small number of studies have investigated the potential for deploying a series of lights along the roadway shoulder that flash at predetermined rates, with the intent of encouraging drivers to reduce speed.
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48 2.2 mph and the 85th percentile speed decreased by 1.0 mph; however, the speed standard deviation (a measure of speed variation) increased by 0.91 mph.
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