Project Improvements to Roadside Sign Hardware and Design

Transcription

1 Project Improvements to Roadside Sign Hardware and Design PD: Doug Skowronek, P.E. (TRF) RS: Roger Bligh, Ph.D., P.E. (TTI) 86 th Annual Transportation Short Course October 17, 2012

2 Introduction 3-Year Project Research issues identified & prioritized by PD and PMC each FY Scope includes sign hardware Work plan, cost, & schedule developed for each research issue Research issues addressed in priority order based on available resources

3 Advisory Panel Karl Janak (CST) Christina Gutierrez (CST) Armen Miskarov (BRG) Charlie Wicker (TRF) Bryan Reed (LBB) Larry Colclasure (WAC) Carlos Ibarra (ATL) Wade Odell (RTI)

4 Research Topics Guidance for Minimum Sign Area for Slip Base Supports Mounting Standards for Chevrons and Mile Markers Analysis of Reported U Bracket Failures on Schedule 80 Pipe Supports Analysis of Wind-Induced Failures of Large Guide Signs Optimized Fuse Plates for Large Guide Signs Evaluation of Stiffeners on Extruded Aluminum Sign Panels Use of Schedule 40 pipe as Intermediate Small Sign Support Sign Capacity of Single Schedule 80 Pipe Support

5 Guidance for Minimum Sign Area for Slip Base Supports

6 Background Current TxDOT Slip Base System: 10 BWG (0.134 thick) A sign 16 ft 2 Sch 80 (0.276 thick) A sign 32 ft 2 NO min sign area requirement w/ slip base (signs as small as 4 ft 2 on Sch 80) Recent testing of small signs on - Lower center of mass and mass moment of slip bases has raised concern inertia - Decreases point of rotation - Increases rotational velocity - Higher probability for secondary contact - Observed Occupant Compartment Deformation (roof ) 5 6 inches MASH - Occ. Comp. Def. 4

7 Research Approach Conduct FEA Parametric Study of Impact Performance of Slip Base Support ft 2 A sign BWG-10, Sch 80, Sch 40 Pipe Supports Plain and T-Bracket Pipes 1100C (Passenger Car) and 2270P (Pickup-Quad Cab) Vehicles Perform Crash Tests for Verification of Impact Performance

8 Full-Scale Crash Tests 12 ft 2 A sign BWG-10 Support T-Bracket 7 Mounting Height MASH Criteria 2270P Pickup-Quad Cab Roof Impact, Occ. Comp. Def.: C Passenger Car Roof Impact, Occ. Comp. Def.: 4.75

9 Full-Scale Test Increased Sign Area 1100C Passenger Car 14 ft 2 A sign, 7 Mounting Height BWG-10 Support Roof Impact, Occ. Comp. Def.: 2.5

10 Full-Scale Crash Test (Pass)

11 Full-Scale Crash Test (Fail)

12 Recommendations Sign Area (ft 2 ) System Nominal Diameter (in) Pole Type 0-14 Wedge and Socket 2 BWG Slip Base 2.5 BWG Slip Base 2.5 Sch-80

13 Summary Identified Minimum Sign Area for Slip Base Sign Support Systems (14 ft 2 ) Provides Increased Safety for Motorists Implementation by TRF through Revision of SMD Sheets

14 Analysis of Wind-Induced Failures of Large Guide Signs

15 Failures Reported by Districts Numerous failures reported across the state Majority clustered in NE & West Texas Districts Repeated failures at many locations

16 Failure Modes Bending of Post

17 Analysis Results Existing Guidelines Overestimate Capacity of Some Supports Guidelines base on post bending capacity Fuse plate controls capacity in many instances e.g. W6x9 vs W6x12 New Wind Load Charts Required Fully account for all failure modes

18 Current Sign Support Selection Chart (90 MPH)

19 New Sign Support Selection Chart A (90MPH)

20 New Sign Support Selection Chart B (90MPH)

21 Summary Current Guidelines Overestimate Capacity of Some Large Guide Sign Supports Resulted in numerous wind-induced fuse plate failures New Wind Load Charts Developed 70, 80, and 90mph Reduced Maintenance Costs Fewer failures Implementation by TRF through revision of SMD Sheets

22 Evaluation of Stiffeners on Extruded Aluminum Sign Panels

23 Objective Analyze Need for Vertical Stiffeners on Extruded Aluminum Sign Panels Service (wind) loads Impact loads activation of slip base

24 Current Stiffener Details Stiffener Details S3x5.7 Within 6 of support post Midspan for large post spacing Attach to sign time intensive Requires large number of fasteners Must be assembled in sequence Reported injury to TxDOT Employee by falling stiffener

25 Static Testing

26 Capacity With and Without Stiffeners

27 Summary Vertical Stiffeners Not Required on Extruded Aluminum Sign Panels Significant cost savings Improved installation safety for sign crews Stiffeners (Permanent or Temporary) Can be Used to Assist with Handling and Installation Implementation by TRF through Revision of SMD sheets

28 Revised D&OM Standards

29

30 Full-Scale Crash Test (TWT)

31 Questions?