FHWA Resource Center
The focus of this meeting was to discuss structural details for Traffic Signals and Directional Signs.
• Introductions; Attendee list attached
o States and Agencies represented: Pennsylvania, New Jersey, Delaware and FHWA
o Consultant: Royen Tech.
• Traffic Signal Structural Standards
o NJDOT’s traffic signal standards were issued in 2001
• Obtained the designs from manufacturers and adopted them as standards
• P.B. is design consultant investigating design for Category II or III.
• Up to 65’ mast arms
• Does not allow any wire spans for permanent conditions
• Materials—Galvanized steel
o DelDOT’s standards were recently revised and issued
• Standards allow X-spans and wire spans for permanent applications
• Material—generally, galvanized. In high price areas- galvanized and painted
o PENNDOT’s standards are currently being updated
• Being investigated for Category II and Category III fatigue
• The 1989 standards that are currently in use are performance based
• High-Mast Poles
o Both PA and NJ have had failures of high mast poles due to corrosion
o DelDOT has had failures in their lap splices, i.e., cracking.
o Materials—NJ uses weathering steel; PA and DE use galvanized steel
o Minimum thicknesses—PA uses 5/16” min. wall thickness at base and 3” thick base plates; NJ uses ¼” at bottom and tapers to 3/16”, 1 ½” thick base plates for 100’ poles
o DelDOT just completed inspection of sign structures, high mast poles and traffic signals
• Cracking found on aluminum structures
• Cracking in anchor bolts in cantilever structures w/ 4-bolt bases, replaced 11 structures with new 8-bolt bases.
• 2 failures of aluminum sign panels. The studs that attached panels to member failed.
• Inspection program- Overhead sign structures every 5 years; Cantilever structures with 4-bolt base plates are inspected every year; Traffic signals are inspected every 10 years
o PENNDOT inspects overhead sign structures every 10 years
• There is currently new criteria that calls for shorter inspection intervals
• PA has 2200 sign structures
• Only one inspection of a high mast pole
o NJDOT has an inspection program for overhead sign structures
• Does not have inspection program for traffic signals
• Inspection program for High mast poles
• During first inspection, tags were attached that identify structure for tracking purposes; it was noted that NY state also does this.
o There is an NHI course for Inspection of Sign Structures currently being presented by Collins Engineering around the country
o Maryland has an UT testing procedure for anchor bolts.
o FHWA has a guide for sign structure inspection, inventory, etc.
o Field Inspection—No state could verify installation inspection such as anchor bolt installation. Will Follow-up with instruction.
• Fiber Reinforced Polymer (FRP) Wrap
o NY and UT states have used FRP wraps for retrofitting aluminum sign structures.
o NJ has used FRP wrap on 1 aluminum structure
• It was used as a temporary repair
• Cost about $3000/ joint
• Traffic Signal Base Plate Details
o The Texas Pooled Fund study entitled, “Investigation of the Fatigue Life of Steel Base Plate to Pole Connections for Traffic Structures” will be completed circa 2008
• DelDOT uses 4 – 2” diameter anchor bolts (105 ksi)
• PENNDOT uses 6 anchor bolts (55ksi)
• NJDOT is still awaiting research results for final recommendations
o Base plates…
• NJDOT and PENNDOT thicknesses are still under development
• DelDOT uses 2” thickness
• NJDOT does not use grout under base plates
• Committee suggested use of 2” minimum thickness for ease of fabrication
• Committee prefers uses of circular base plates
o Suppliers--- Valmont, Union Metal, Lehigh Utility, and Value Structures
o DelDOT uses 14” diameter poles and 20” diameter bolt patterns for standards, inventory control.
o The committee recommends the following:
• Increments--- For base plate thicknesses, use increments of 0.25”; For anchor bolt diameters, use increments of 0.25”
• To consider either 2 or 3 standard bolt patterns and anchor bolt sizes
• The use of a single leveling nut and a double top nut
• The use of an embedded plate (approximately ¾” thickness) to hold anchor bolts
• Will send proposed details (once completed) to the 4 suppliers listed above for comment
o DelDOT>> A595 or A607 Gr. A, A572 or A1011, Gr. 55
o NJDOT>> A585 Gr. A, A607 Gr. 50 (min.), A572 Gr. 50 (min.)
o PENNDOT>> A53/ A53M, A252, A595 A1008
• Design Wind Speeds
o PENNDOT uses AASHTO Sign Specification (2001) Appendix C with 80 mph
o NJDOT uses AASHTO Sign Specification (2001) Appendix C with 90 mph
o DelDOT to follow up with verification of wind speed.
• Mast Arm Connections
o NJ uses a bolted, friction connection with a welded plate.
o The committee would like to develop a standard the connection. It will investigate 2 alternatives from the 2001 AASHTO Sign Specification: On page 11-20, Example 8 and on page 11-23, Example 16.
Summary of Discussions
Item Delaware DOT New Jersey DOT Pennsylvania DOT
Traffic Signal Structural Standards o Recently revised and issued
o Allow X-spans and Wire spans for permanent
o Material is galvanized; sometimes, galvanized and painted o Issued in 2001
o Obtained designs from manufacturers
o Up to 65’ mast arms
o Does not allow wire spans for permanent
o Material is galvanized steel o Currently being updated
o Being investigated for Category II and III fatigue
o 1989 standards are performance based
Inspection o Just completed inspection of sign structures, high mast poles and traffic signals
o Inspect Overhead sign structures every 5 years, Traffic signals every 10 years, 4-bolt base cantilevers every year o Has inspection program for OSS’s but not traffic signals
o Could not verify High mast inspections, will verify
o Has tags on structures to identify o Inspects OSS’s every 10 years
o PA has 2200 Sign structures
o 1 inspection of a high mast pole
Traffic Signal Base Plate Details Bolts 4- 2” diam. Anchor Bolts (105 ksi) Awaiting Research 6 Anchor Bolts (55ksi)
Base Plates 2” Thickness Under Development Under Development
High-Mast Poles Failures? Yes, in lap splices Yes, due to corrosion Yes, due to corrosion
Material Galvanized Steel Weathering Steel Galvanized Steel
Wall Thick. Under development ¼” at bottom, tapers to 3/16” 5/16” at base
Base Thick. 1 ½” for 100’ poles 3”
Materials A595 or A607 Gr. A, A572 or A1011, Gr. 55 A595 Gr. A, A607 Gr. 50 (min.), A572 Gr. 50 (min.) A53/ A53M, A252, A595 A1008
Design Wind Speed Will follow-up AASHTO App. C; 90 mph AASHTO App. C; 80 mph
Committee Recommendations o Increments--- For base plate thicknesses, use increments of 0.25”; For anchor bolt diameters, use increments of 0.25”
o To consider either 2 or 3 standard bolt patterns and anchor bolt sizes
o The use of a single leveling nut and a double top nut
o The use of an embedded plate (approximately ¾” thickness) to hold anchor bolts
o Will send proposed details (once completed) to the 4 suppliers listed above for comment
o The committee would like to develop a standard mast arm connection. It will investigate 2 alternatives from the 2001 AASHTO Sign Specification: On page 11-20, Example 8 and on page 11-23, Example 16.