01592095

Component

https://doi.org/10.3141/2555-15

Warning signs are used to warn road users of potential hazards located in or near a roadway. A properly placed warning sign provides the road user with adequate time to select and execute the proper response. Table 2C-4 in the 2009 edition of the Manual on Uniform Traffic Control Devices presents recommended advance placement distances for warning signs on the basis of the approach speed and the appropriate speed at which to negotiate through the hazard. These placement distances are determined through use of the AASHTO stopping distance equation with assumptions for reaction, deceleration, and sign legibility distances. A recent NCHRP study measured continuous driver deceleration on the approach to and through a change in horizontal alignment. The findings from that research were combined with more appropriate selections of response time and legibility distances to develop improved recommendations for the advance placement of warning signs on the approach to a change in horizontal alignment. With the use of these new assumptions, a new table was created on advance placement distances for warning signs placed in advance of changes in horizontal alignment. The table indicates that the advance placement is similar to the current values when speeds are 50 mph and lower. For higher speeds, the warning signs should be placed up to 75 ft farther from the start of the alignment change than when the advisory speed is low. The signs can be placed up to 100 ft closer to the start of the alignment change when the advisory speed is within 20 mph of the approach speed.

01594662

16-1748

English

pp 111–119

2016

Transportation Research Record: Journal of the Transportation Research Board

9780309441193

Print

Figures (3) ; References (14) ; Tables (7)

Deceleration; Distance; Highway curves; Location; Turning traffic; Warning signs

Highways; Operations and Traffic Management; Safety and Human Factors

TRIS, TRB, ATRI

Jan 12 2016 4:45PM

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• Guidelines for Traffic Control Devices at Changes in Horizontal Alignment
• Impact of Advisory Signs on Vehicle Speeds in Highway Nighttime Paving Project Work Zones
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• Model Development for Use of Portable Traffic Signals in Conjunction with Pilot Car Operations at Two-Lane, Two-Way Rural Highway Work Zones
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• Road Lighting Effects on Bicycle and Pedestrian Accident Frequency: Case Study in Montreal, Quebec, Canada
• Safety Effects of Portable End-of-Queue Warning System Deployments at Texas Work Zones
• Safety Effects of Street Illuminance at Urban Signalized Intersections in Florida
• Traffic Control at Access Points Within Alternating One-Way Operations
• Variable Speed Limit Study Upstream of an Indiana Work Zone with Vehicle Matching
• What Role Do Precrash Driver Actions Play in Work Zone Crashes? Application of Hierarchical Models to Crash Data
• Work Zone Crash Cost Prediction with a Least Median Squares Linear Regression Model