LATEST DEVELOPMENTS IN BRIDGE RAILS...Latest Developments in Bridge Rails (The crash test videos you want to SEE!) LATEST DEVELOPMENTS IN BRIDGE RAILS Amy Smith, P.E., Bridge Division

Latest Developments in Bridge Rails

(The crash test videos you want to SEE!)

LATEST DEVELOPMENTS IN BRIDGE RAILS

Amy Smith, P.E., Bridge Division


Table of Contents

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Crash Testing Primer

New Rails

Rail Not Under Development

Rail Under Development

Summary

Resources for Bridge Rail Questions

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WHO and WHAT – Bridge railing BRG – Barriers DES – Sign mounts, work zone devices TRF – Mailbox mounts MNT

WHERE – TAMU Transportation Institute, Roadside Safety

WHY – FHWA requires – TxDOT Goal “Maintain a safe system”

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Testing criteria – Manual for Assessing Safety Hardware (MASH)

• Current • Implemented in 2009

– NCHRP Report 350 • Previous • These rails are still acceptable

– Why updated? • Recognizes changes in vehicles on roadway • CG moved up • Heavier car and pickup • More severe TL-4 criteria

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TxDOT bridge rail levels


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Low speed High speed ≤ 45mph ≥ 50mph TL-2 * TL-3 *

TL-4 # TL-5

* minimum required by TxDOT policy

# recommended for bridges carrying the main lanes of interstate and divided highways

TL-4 rails – T221 – T223 – T551 – SSTR – C412



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Factors Evaluation Criteria Structural Adequacy Contain and redirect vehicle or bring to controlled

stop

Occupant Risk

No elements penetrating occupant compartment; Limits on deformation of occupant compartment Vehicle remains upright, with limited roll and pitch Limit on occupant impact velocity Limit on occupant ridedown acceleration

Vehicle Trajectory Vehicle exits the barrier within the exit box

What is a PASS or FAIL?



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What is a PASS or FAIL? What about if the bridge rail is damaged?

– Not a failing criteria for MASH – Can be a concern for BRG

• Increases the maintenance cost over life of installation


New Rails

T131RC Picket rail

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New Rail –T131RC

T131RC – A retrofit rail used only on curbs – Replacement of the T101RC – Crash tested MASH TL-3, including guardrail transition tests – Test specimen included a lightly reinforced curb – 36” tall

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New Rail – T131RC

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https://www.youtube.com/watch?v=Ue7SQ7wydZM#t=08m14s


New Rail – T131RC

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New Rail – T131RC

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Factors Evaluation Criteria

Structural Adequacy

Contain and redirect

Occupant Risk

Occupant compartment penetration Occupant compartment deformation

Vehicle upright

Occupant impact velocity

Occupant ridedown acceleration

Vehicle Trajectory

Exits within the exit box

Successful test results Curb and slab damage

– Hard to avoid

Guide drawing was issued November 2012


Rails Under Development – Picket Rail

Picket Rail – A 36” steel rail targeted for historic bridge preservation projects – Texas Historical Commission involved in the development – Crash tested for MASH TL-3

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Rail didn’t budge Little damage to slab, curb or rail Expect to see minimal maintenance

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Structural Adequacy


Occupant Risk

Occupant compartment deformation

Vehicle upright



Vehicle Trajectory


Successful test results

Target to post as a standard November 2013 Currently considering a combination version for use with

sidewalk


Rails Not Under Development

T101 T131

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Rails Not Under Development – T101

T101 needed to be tested for pickup – Rail only 27”, critical height in past testing – Tested for MASH TL-3 with pickup

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Unsuccessful test results – Pickup rolled excessively

Retired effective September 2012

Per Bridge Railing Manual – T101 can remain in place for certain work categories

BRG always encourages its replacement when possible


Structural Adequacy


Occupant Risk


Vehicle upright



Vehicle Trajectory




T131 considered to replace T101 – Rail height 31” – Tested for MASH TL-3 with pickup

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Unsuccessful test results – Pickup rolled over

Not pursued further


Structural Adequacy


Occupant Risk


Vehicle upright



Vehicle Trajectory



Rails Under Development

T631 T221P

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Rails Under Development – T631

T631 is a replacement for the T6 – T6 was retired

September 2012; only 27” tall

– New rail is 31” tall – Single W-beam on

weak posts – Crash tested for

MASH TL-2

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Structural Adequacy


Occupant Risk


Vehicle upright



Vehicle Trajectory


Successful test results No deck damage

Target to post as a standard November 2013 Estimated cost $23/LF Will be a maintenance cost associated

– Replacing posts – Replacing W-beam



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Successful T631 has spurred development of another rail – A TL-3 version for high speed application – A precedent exists in a similar rail tested elsewhere

If it works, would replace the T101 (& T131 that never made it)


Rails Under Development

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T221P – Precast version of the T221 – Bolts to bridge deck – Can be used in permanent or

temporary installation – Crash tested for MASH TL-3


Rails Under Development – T221P

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Rotation of rail panel and slab overhang – Permanent deflection – Slab cracked



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Structural Adequacy


Occupant Risk


Vehicle upright



Vehicle Trajectory


Unsuccessful test results Pickup snagged on rail

panel

Work is on-going to modify the design and re-test


Summary

Already out Coming soon In the works T131RC Picket rail T221P

T631 High speed T631

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TxDOT has a number of new rails that: – Meet updated crash test requirements – Meet broader range of needs – Provide more options


Resources for Bridge Rail Questions

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– What type should I use? – How tall are those rails? – How do I retrofit a rail on this bridge?

Resources

– Bridge Railing Manual • txdot.gov

– Bridge Railing Q&A • Crossroads BRG

– Standards Webpage • Retrofit guide drawings

– Webinar presentation • For C-Rail-R Guide Drawing • Posted on txdot.gov BRG

page


Questions about bridge rails

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Have more questions?



Name Description Height TL Criteria T1F Stl Post w/Alum Tube & Opt Drains (33” tall) 33 3 MASH T1W Stl Post w/Stl Tube & Opt Drains (32” tall) 32 3 350 T221 Concrete Parapet (32” tall) 32 4 350 T223 Conc Bm & Post w/6’ Openings (32” tall) 32 4 350 T401 Concrete Parapet w/Stl Post and Rail (33” tall) 33 3 350 T402 Concrete Parapet w/Stl Post and Rail (42” tall) 42 3 350 T411 Conc Traf Rail w/Windows(Tx Classic)(32” tall) 32 2 350 T551 Concrete Safety F-Shape (32” tall) 32 4 350 T552 T551 w/Multiple Drain Slots (32” tall) 32 4 350 T66 Conc Bm, Post & Curb w/5.25’ Max Open (32” tall) 32 3 350 T77 Steel Post w/Two Elliptical Pipes (33” tall) 33 3 350

SSTR Conc Single Slope Traffic Rail (36” tall) 36 4 MASH T80HT Conc & Steel Heavy Truck Traffic Rail (50” tall) 50 5 350 T80SS Conc Single Slp Hvy Truck Traff Rail (42” tall) 42 5 350

C1W Steel Post w/Stl Tube & Opt Curb Drain (42” tall) 42 2 350 C221 T221 w/Steel Pipe Rail (42” tall) 42 2 350 C223 T223 w/Steel Pipe Rail (42” tall) 42 2 350 C402 T402 w/Steel Pipe Rail (42” tall) 42 3 350 C411 Comb Rail w/windows (Tx Classic) (42” tall) 42 2 350 C412 Conc Comb Rail w/Windows (TL-4) (42” tall) 42 4 350

T131RC Retrofit Guide for Curbed Structures 36 3 MASH

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Current BRG Rail Inventory

Documents

LATEST DEVELOPMENTS IN BRIDGE RAILS...Latest Developments in Bridge Rails (The crash test videos you want to SEE!) LATEST DEVELOPMENTS IN BRIDGE RAILS Amy Smith, P.E., Bridge Division