Spacing Chevrons on Horizontal Curves

Abstract

chevron alignment sign is an important traffic control device used to warn drivers of severity of a curve by delineating alignment of road around that curve. FHWA's Manual on Uniform Traffic Control Devices for Streets and Highways provides following guidance on spacing of chevrons around a curve: The Chevron Alignment sign should be spaced such that road user always has at least two in view, until change in alignment eliminates need for signs and the Chevrons should be visible for a sufficient distance to provide road user with adequate time to react to change in alignment. This guidance is broad to account for geometric design features and site obstructions such as steep vertical curvature or heavy vegetation. It also allows flexibility based on site characteristics and available funds, and use of this verbiage creates a lower liability risk than there would be if a spacing chart were used. However, broad wording allows for inconsistencies in roadway system and provides little guidance for maintenance personnel. A field study was conducted to investigate impacts of varying number of chevrons in view around a curve. A spacing chart was then developed to simplify maintenance personnel's responsibility for choosing appropriate chevron spacing. results of field study indicated that having more than two chevrons in view around curve provided a benefit in form of a reduction in speed of about 3 mph at night. Smaller speed reductions were observed during daylight.