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FHWA Resource Center

STRUCTURES TEAM


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.

General Discussions…


• 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


• Inspection
     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
     o Bolts…


• 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


• Materials
     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.

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