Work Zone Materials for Temporary Signs in High Wind Areas: Final ReportAuthor/Presenter: Qiao, Fengxiang; Du, Jianbang; Zhou, Lijie; Bakare, Abayomi
Due to ineffective ballast materials and techniques, temporary signs may easily be knocked down and become invisible to the traveling public, increasing the risk of tort liability. Signs in construction zones must be properly secured to prevent wind from blowing them off posts, and the conditions should be checked periodically to ensure specification compliance. This project’s objectives were to understand the need for and concerns surrounding temporary traffic signs in Texas work zones, and conduct a cost/benefit analysis to evaluate the cost-effectiveness of each identified technology or materials. During this project, the research team conducted an intensive literature review and evaluated the techniques and materials that reduce temporary signs from falling over due to high winds, as well as surveying Texas engineers. The team collected field observations in several high-wind Texas regions and conducted a cost-benefit analysis a finite element analysis for different types of temporary signs. Based on the results, the research team proposed a map of recommended signs in Texas and the months to apply. The research team found that there each TxDOT distract has its own most suitable temporary traffic signs for work zones. Based on 25 years mean recurrence interval of fastest mile wind velocity at 33 feet high, there are three types of wind zones in Texas for large traffic signs. Zone 1 is with 90 mph fastest wind, Zone 2 is with 80 mph fastest wind, and Zone 3 is with 70 mph fastest wind. It is recommended that, (1) in Zone 1 during certain specific months, the embedding signs are mandatorily recommended like the Dual Leg Perforated Square Metal Tubing with Anchor Sign and three of its updated new versions proposed in the project, while skid signs are not recommended then; (2) in Zone 2 during certain specific months, the embedding signs are highly recommended, while skid signs shall be limited for use including (a) the Independent Dual Upright with Leg PSST Skid Sign, and (b) the Dual Leg PSST Skid Support Sign; and (3) both embedding signs and skid signs can be used during all months of the years for Zone 3, and during the rest months of the year for Zone 1 and Zone 2. The wooden signs (such as the Wooden Skid with 2 Wooden Legs Sign, and Wooden long/intermediate-term Single Leg (H-leg) Sign) are also good choices for non-high wind situations.The above recommendations on zones and months to apply are based on wind historical records. In the cases that extremely higher wind is forecasted in any area in Texas, embedding signs shall always be highly demanded.