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Publication Number: FHWA-HRT-09-046
Date: August 2009
Safety Evaluation of Improved Curve Delineation: 508 Captions
FHWA Contact: Roya Amjadi,
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Figure 1. Photo. Example of curve treated with enhanced delineations in Connecticut. This photo shows an example of improved curve delineation along a two-lane undivided roadway with a curve to the left. The road is seen in a suburban neighborhood. There is a double yellow centerline and two white edge lines on the outside edge of the lanes, one in either direction, to designate the lanes. The roadway has curbs, gutters, and narrow shoulders. There are four utility poles shown along the outside of the curve on the right, and one pole has a street light attached. There is a narrow grass buffer on the right side of the road and then a sidewalk. Near the beginning of the curve, there is a curve warning sign. The sign is diamond-shaped and mounted into the ground with two posts. It is yellow with a black arrow that illustrates a 45-degree turn to the left, including a side road to the right along the curve. Below the sign, there is a supplemental plaque attached to it that reads, "20 M.P.H," indicating a 32.2-km/h (20-mi/h) advisory speed. The supplemental plaque is square-shaped and yellow with black text. The following three signs in the sequence are chevrons, which indicate the presence and direction of the curve. These signs are yellow with a black symbol that points to the left. They are mounted in the ground with one pole per sign. The black symbol is created by a black line from the upper right corner to the middle left of the sign and another black line from the middle left to the lower right corner, forming a point facing left. Each of the chevron sign posts also has a yellow reflective stripe. All curve warning signs include a "No Parking Anytime" sign on the sign posts.
Figure 2. Chart. Sign types used in Connecticut horizontal curve treatments from MUTCD. Eight examples of curve warning signs are shown. The signs are arranged in two rows with four signs in each row. Six of the signs are diamond shape (the entire top row and first two signs on the left on the second row), and the last two signs are rectangular in shape. All signs have a black symbol on a yellow background. From left to right, the top row of signs is shown with identification numbers under each sign as follows: "W1-1," "W1-2," "W1-3," and "W1-4." The W1-1 sign is a black arrow that starts as a vertical line from the bottom and forms a 90-degree angle to the left. The W1-2 sign is a black arrow that starts as a vertical line from the bottom and then curves at a 45-degree angle to the left. The W1-3 sign is a black arrow that starts as a vertical line from the bottom, turns at a 90-degree angle to the left, and then turns at a 90-degree angle to the right to end as a vertical line. The W1-4 sign is a black arrow that starts as a vertical line from the bottom, curves at a 45-degree angle to the left, and then curves back 45 degrees to the right to end as a vertical line. From left to right, the second row of signs is shown with identification numbers under each sign as follows: "W1-5," "W1-10," "W1-6," and "W1-8." The W1-5 sign is a black arrow that starts as a vertical line from the bottom and curves to the right, back to the left, and back to the right, ending as a vertical line. The W1-10 sign is a black arrow that starts as a vertical line from the bottom and then turns at a 45-degree angle to the right. Where the line turns 45 degrees, there is a perpendicular line toward the upper left of the sign, indicating that there is a side road off of the curve. The W1-6 sign is a horizontal black arrow pointing toward the left. The W1-8 sign is a black symbol that forms the top of an arrow pointing to the left. The black symbol is created by a black line from the upper right corner to the middle left of the sign and another black line from the middle left to the lower right corner.
Topics: research, safety, local & rural road safety
Keywords: research, safety, Horizontal curve, Curve delineation, Low-cost, Safety improvement, Safety evaluation, Empirical Bayesian, Chevrons, Horizontal arrows, Advance warning signs, Sign upgrade, and fluorescent yellow sheeting
TRT Terms: Curves in engineering, Traffic safety, Traffic accidents, Highway curves, Highway delineators, Road markings