FHWA Resource Center
SCEF Sign Structure Task Force Meeting #5
February 1, 2007, PennDOT District 6-0 Office, King of Prussia, PA
The meeting was led by Brandon R. Motuk of PennDOT. Attendees were from PennDOT (3), MDDOT/SHA (2), NJDOT (2), DelDOT (1), TRB/AFF10(1) (Ronnie Medlock) and Consultant Royen Tech (Roy Nooreyazdan).
2. General discussion – Recent Design, Fabrication, and In-service issues
- Preliminary investigation report on PenDOT aluminum lighting pole failure (erection problem caused fatigue failure)
- Cracking in VMS Sign Structures (PennDOT)
- State erection requirements – most problems are due to improper construction
- QA/QC process check list; Fabrication/Field inspection requirements
- Suggest third party inspection
- All four states have full or partial inspection program. MDDOT/SHA has inspection program for sign structures using check list, now has FHWA/NHI Training; NJDOT has inspection program for sign and high mast pole structures using FHWA Guidelines (most FHWA Guidelines based on NJDOT’s pratice); Basically, every 5 years. Signal inspection (visual) every year. DelDOT inspects sign structures every 5 years, traffic signal structures very 10 years, 4-bolt base cantilevers every year. PennDOT inspects overhead sign structures every 10 years.
- MDDOT/SHA has problems with nuts and bolts; NJDOT has most problem with aluminum structures; Both have no problem with socket weld detail.
- PA, MD, NJ no new use of Aluminum; only use of Steel
- Monotube sign structures: used by airport/turnpike authorities. Not these State DOTs.
- Design: PA: new design is so heavy and need look at economy
MD: no tri-chord any more; stable box truss; no tube-to-tube welds
NJ has done the same since 1980s.
MD allows only one VMS box in a structure
PA had welding fabrication problem with VMS attached to a single post structure
NJ prefers thinner VMS box as possible
- Electronic Drawings Approval
AutoCADD (MicroStation), pdf, tif, FTP ect.
3. Review of Discussions from Meeting #4
- Revised the Summary of Discussion from Meeting #4, which summarized Traffic Signal Structural Standards, Inspection, Traffic Signal Base Plate Details, High-Mast Poles, Materials, Design Wind Speed.
- Committee Recommendations:
• Use 0.25” for increment of base plate thickness and anchor bolts diameter
• Use 2-3 standard bolt patterns and anchor bolt sizes
• Use single leveling nut and double top nuts
• Use an embedded anchor plate (~3/4”) to hold anchor bolts
4. Discussion of Proper Detailing for Mast-Arm Connection (Follow-up from Meeting #4)
- Develop a standard signal mast-arm to pole connection by investigating 2 alternatives from AASHTO Example 8 and Example 16.
5. High-Mast Pole Discussion
a. Virginia DOT Recent High Mast Pole Failure (See SCEF full meeting notes)
b. Current practice
- Height: MA 120’; PA 120’; NJ 100’;
- Pole wall thickness: MA 5/16”, PA 5/16”; NJ ¼”
- Materials: MA?; PA galvanized steel; NJ weathering steel; DE galvanized steel
- Base plate thickness: MA ?; PA 3”; NJ 1-½”; DE under development
- Stiffeners: MA yes; PA no; NJ no;
- Failure: MA no; PA corrosion; NJ corrosion; DE cracking lap slice
- To avoid corrosion from vegetation moisture, the Committee suggested concrete pedestal height be raised (no grout filling).
- The Committee questioned the current AASHTO lateral deflection of 15% of height. Ronnie Medlock will forward the concerns to the AASHTO T-12 Committee.
6. Discussion of New TRB Traffic Structures Sub-Committee
- Ronnie Medlock, Chair of TRB/AFF10(1), introduced the new subcommittee’s scope, members/friends list, research updates/activities, research needs, as well as the research presentations at January TRB annual meeting in DC (Iowa high mast lighting tower; Signal pole and high mast pole pooled fund fatigue study; overhead sign structure vibration; NCHRP project 10-70 update for fatigue resistant detail development).
7. Recommendations for full SCEF Committee
Full SCEF Committee meeting to be held on February 6, 2007 at Atlantic City, NJ (See SCEF full meeting notes)