John M. Holt, P.E. Transportation Short Course October 2012

Transcription

1 What s Up With These New Bridge Rails? John M. Holt, P.E. Transportation Short Course October 2012

2 Agents of Change Outline Bridge Railing Manual New Rails T131RC, T1W, C1W, T1F, T66, Picket Rail, T80SS, T80HT, T80TT, and PR3 Rails Under Development Rails Not Under Development Summary

3 Agents of Change Adoption of MASH More severe small car impact angle Heavier pickup with higher c.g. More severe TL-4 requirements Adoption of 31 tall guardrail 31 doesn t equal 27 no more T6, T101, and T101RC, but T6 still allowed as temporary rail for phased bridge construction

4 AASHTO LRFD Agents of Change Bicycle rail height reduced from 54 to 42 Historic bridge preservation Need modern crashworthy rails

5 Bridge Railing Manual Significantly Revised in April 2012 Included new rail types Noted future retirement of T101, T6, etc., with adoption of 31 tall guardrail Provides list of in-service rails that are considered to meet current requirements Provides a table of actions necessary for existing rails based on project type References adoption of Manual for Assessing Safety Hardware (MASH)

6 New Rails Type T131RC The replacement of the T101RC Crash tested by TTI to meet MASH Test Level 3, including guardrail transition tests Test specimen included a lightly reinforced curb 36 tall rail Standard will be issued in October or November

7 New Rails Type T131RC

8 New Rails Type T131RC

9 New Rails Type T131RC

10 New Rails Type T131RC

11 New Rails Type T131RC

12 New Rails Type T1W A Texas version of the Wyoming TL-3 Rail Evaluated for Test Level 3 32 tall overall, with a 9 tall curb, two 6 x 2 x ¼ HSS rails, and steel posts Best railing for allowing flood waters to pass through Most open rail type in TxDOT inventory

13 New Rails Type T1W

14 New Rails Type T1W

15 New Rails Type C1W A combination pedestrian/traffic version of the T1W Evaluated for Test Level 2 42 tall overall, with 9 tall curb, four 6 x 2 x ¼ HSS rails, and steel posts Most open and lightest combination rail in TxDOT inventory

16 New Rails Type C1W

17 New Rails Type C1W

18 New Rails Type T1F A unique 33 tall rail developed to take advantage of the constructability offered by the aluminum half-ellipse rail Our first rail evaluated with MASH criteria

19 New Rails Type T1F

20 New Rails Type T66 A 32 tall concrete rail meant to replicate the style of the old Type K rail Derived from the Caltrans Type 80 rail Altered post geometry from the Caltrans original

21 New Rails Type T66

22 New Rails Type T66

23 New Rails Picket Rail A 36 steel rail targeted for historic bridge preservation projects Texas Historical Commission involved in development TTI crash tested this rail successfully at MASH TL-3

24 New Rails Picket Rail

25 New Rails Picket Rail

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28 New Rails Picket Rail

29 New Rails Picket Rail

30 New Rails T80SS 42 tall single slope rail that meets TL-5 Matches 42 SSCB Least expensive TL-5 rail in TxDOT inventory

31 New Rails T80HT An updated version of the Type HT with an F-shape profile combined with inline anchor bolts 50 tall overall

32 New Rails T80TT An updated version of the Type TT switched to a single slope base section and eliminated windows 90 Tall, weighs 1260 plf Used in the Dallas District recently Not issued as a standard rail

33 New Rails PR3 Rail A tall steel picket pedestrian rail A bicycle rail version, the B3, was developed and issued as a standard, but was retired when AASHTO reduced the minimum bicycle rail height to 42.

34 New Rails PR3 Rail Photo of Type B3 rail, now retired with change in minimum bicycle rail height Type PR3 is similar, 12 shorter

35 New Rails PR3 Rail

36 Rails Under Development A replacement for the T6 Goals: Can be used to replace existing T6 installations, if necessary Compatible with 31 tall guardrail Could be used as a temporary rail Test Level 2 installations Crash testing scheduled this FY

37 Rails Not Under Development A replacement for the T101 We ve tried

38 T101, MASH TL-3, Pickup

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41 T131, MASH TL-3, Pickup The T131 represents a replacement to the T101

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43 Summary TxDOT has a number of new rails that: Meet updated crash test requirements Should require less maintenance after hits Look better Meet broader range of needs Provide more options

44 Questions? Or Call