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Component-Level Risk Management for Highway Tunnelsg y

Steve Ernst for the Transportation Security Administration

Bruce A. WaltonU.S. Army Corps of Engineers, Omaha District Protective Design Center

US Army Corps of EngineersBUILDING STRONG®1

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P i D i CProtective Design CenterArmy's center of expertise ‐protection and protective designprotection and protective design

Wartime threats, secure storage, accidental explosions, classified programs

Security engineering Vulnerability analyses and risk assessmentsassessments

Criteria for Dept. of Defense

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Web Page: https://pdc.usace.army.mil

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Bridge and Tunnel Assessment Program for TSA

Focus on Antiterrorism Vulnerability AssessmentRi k A l i Risk Analysis

Recommended Mitigation Measures (with cost) TSA coordinates with structure owner,

h Three step in process: 1 ‐ Site survey 2 – Risk Assessment  3 – Report to TSA

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Tunnel Assessment Process

Leverage Best Practices and Recommendations from past work: TSA ASCE NCHRP TSWG AASHTOwork: TSA, ASCE, NCHRP, TSWG, AASHTO.

Risk Analyses in Two Separate Parts:

Operation Risk Analysis (Closure), component based

Casualty Risk Analysis (Injury), scenario based

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O i V l bili / Ri kOperation Vulnerability / Risk Identify ThreatsId tif   l bl   t Identify vulnerable components

Vulnerability function of threat size that causes catastrophic damage leading to Operational loss of service for three months

Prioritize For High‐risk combinations: For High‐risk combinations: Validate risk numbers  Evaluate the mitigated risk – risk reduction

B fit i   d b   d ti  i  th t  i Benefit is measured by reduction in threat size

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Threats

VBIED  Vehicle borne improvised explosive device HEIED  Hand‐emplaced improvised explosive devicep p p NECD  Non‐explosive cutting device VI  Vehicular impact – ship impact, anchor drag Fire   Five to Three Hundred MW Fire  ‐ Five to Three Hundred MW

Chemical, Biological, Radiological,  Industrial Chemical S illSpill

AASHTO/FHWA “Recommendations for Bridge and Tunnel gSecurity” by the Blue Ribbon Panel

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Casualty and Damage Calculation A terrorist attack is intentionally and initiated 

quickly.  Fires and chemical releases will occur suddenly.  Blasts will have immediate effects. 

Weapon and geometry Weapon and geometry Use simplified Blast, Fire, and/or Chemical Dispersion 

models. O Outputs:

Blast pressures and Structural damageSurface Temperatures, Smoke, Toxic GasesHuman evacuation routes and timeHuman exposure levels to toxic gasses and chemicals.

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Mitigationg Initial incident ‐ Limit threat access structural and system hardening, hazardous materials drainage systems  and reduce materials drainage systems, and reduce population density in tunnel. 

Occupant Response & Self Rescue ‐decrease evacuation times  reducing decrease evacuation times, reducing hazardous environment in tunnel. 

Response and Rescue – Concept of Operations  Event assessment  Access for Operations, Event assessment, Access for responders, Special rescue equipment, Training, Fire and Utility systems.

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Highway Tunnel Systems

TUNNEL

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VENTILATION TRAFFIC CONTROL

SCAD

ALAR

SENS

CCTV

ACCE

CONT

COMPUTER / NETWORK

A MS

ORS

SS

ROL

POWER

COMPUTER / NETWORK

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C l i Ri kCasualties Risk The casualty risk evaluation procedure is to select a threat size and location and 

then evaluate the current and mitigated state.  The risk reduction value is based on the change in number of casualties.

Weighting Factors

Occurrence Vulnerability Importance

General Threat Likelihood 0.20 Resistance to Threat 1.00Casualty

Importance 1.0

Threat Likelihood At Location 0.60

Likelihood of Specific Threat Size 0.30

Sum 1.00 Sum 1.00

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C l V l bili / Ri k C l l iCasualty Vulnerability / Risk Calculation Use a subset of the identified range of threat sizes, 3 or 4 sizes each. 

VBIED, HEIED, Fire, Chemical (heavier and lighter than air)

Identify critical threat locations in tunnels: Tunnel Tunnel at ventilation building Ventilation building interior and exterior

Estimate vulnerability for each threat‐location scenario by calculating the number of casualties.

Prioritize scenarios using  risk analysis Highest risk scenarios are further evaluated to:g

Validate risk numbers for each scenario Evaluate the mitigated risk reductions The risk reduction value is based on the change in casualties

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Vulnerability Examples Empirical assessment of vulnerability – spreadsheet tool is p y p

simple, fast, not a design tool Shows extent of various effects from VBIED.

Input:Input:DiameterCover depthExplosive W& other parameters& other parametersLengthRoof thicknessPerson/lengthRoad structure P-IRoad structure P IRoof structure P-I

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Ventilation Duct or Roadway Failure Roof or road P‐I damage curve for severe damage is used. 

P‐I curve from SBEDS code. Blast wave propagation in tunnel

pressure decays, impulse is constant

Compare blast pressure to P asymptote since impulse will ll  b  l

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ssur

e, psi

usually be large

0

2

4

0 500 1000 1500 2000 2500

Pres

Distance along tunnel, feet

Slid 1313

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Airblast Injuries Airblast effects:Airblast effects: Crushing automobiles, breaking glass hazards Pressure – ears, organs (lungs)Bl   i d  l i   f  l   d d b i Blast wind translation of people and debris

Pressure vs Human Injury

Psi * % Survival% Casualty

50 5 1 99681012

ure, psi

50.5 1 99

44 10 90

37.5 50 50

30.6 90 10

024

0 500 1000 1500 2000 2500

Pressu

Distance along tunnel, feet

27.5 99 1

* Values for small humanRef FHWA/ERDC curve

Slid 1414

Ref TM 5-1300 Fig 1-2

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Z=R/W 1/3 units m/kg 1/3

Over Pressure Damage on VehiclesWitness Targets – Side On Blast Wave

Z R/W , units m/kg

Z = 2.51 Z = 3.14

Witness Targets – Front On Blast Wave

Z = 1.25, 120 psi Z = 2.51, 25 psi Z = 3.14, 15 psi 15

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Tunnel Fire Damage

CFD codes like the Fire Dynamics Simulator (FDS). Simple models can be run quickly (hours) to get Simple models can be run quickly (hours) to get approximate answers for assessments.

Engineering judgment and empirical damage criteria for systems and concrete and steel tunnel components can systems and concrete and steel tunnel components can then be used to estimate damage to tunnel components, and systems.  For example:

No damage  T < 100 C,                Surface spall  T < 400 C,  Surface spall  T < 400 C,   Heavy damage T > 1000 C.

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Tunnel Fire Damage

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Casualty Fire Calculation Weapon and tunnel geometry input to  simplified fire  Weapon and tunnel geometry input to  simplified fire 

model in FDS‐EVAC code.  Standard and Emergency operating conditions. 

Outputs: Air temperatures  Evacuation routes and  Outputs: Air temperatures, Evacuation routes and times, toxic gas concentrations, exposure levels to toxic gasses, and Purser’s Fractional Effective Dose (FED).(FED).

Casualties caused by attack are estimated. Engineering Judgment. 

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Tunnel Operational Out of Service forTunnel Operational Out of Service for Damage from Industrial Chemical Spill

Engineering judgment and empirical damage criteria. 

Estimated Damage is then used to estimate the  Estimated Damage is then used to estimate the time out of service. 

The time out of service includes investigation, cleanup, decontamination, and repair. 

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Ch i l R l C l C l l iChemical Release Casualty Calculation

For a pressurized gas chemical release scenario in a p gtunnel, the weapon and geometry of the tunnel are input into a simplified Chemical Dispersion model in the Fire Dynamics Simulator FDS‐EVAC codein the Fire Dynamics Simulator FDS EVAC code.

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Chemical Release Casualty Calculation

AUTOMATICALLY CALCULATE  REDUCED EVACUATION  VALUES: Once FDS is run the output file can be processed to calculate the accumulated dose of chlorineof chlorine.

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Program Insights

Bridge Type #  Main Span length Risk 1 Risk 2 Risk 3

Girder 11 < = 600’ VB @ pier,  VB @ girder HE @ girder@ p @ g @ g

Arch 3 240’ to 1000’ VB @ arch rib HE @ column VB @ 

column

Truss 9 250’ to 1600’ VB @ truss Fire @ truss HE @ truss

Suspension 11 1500’ to 4000’ VB @ tower VB @ cable HE @ anchorageg

Bridge Security Checklist – being filled out for each site, will be evaluated/modified in aggregate report.

Note: all bridges surveyed to date have the risk assessment

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Note: all bridges surveyed to date have the risk assessment complete and are included in this table.

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Program InsightsT l T #  L th Ri k  Ri k  Ri k Tunnel Type #  Length Risk 1 Risk 2 Risk 3

Operational Out of Service

Submerged Tube 1 3500’ VB @ vent 

building VB @ tube wall VB @ exhaust ductg

Cut & Cover VB @ exhaust duct

VB @ vent building

Fire @ exhaust duct

Rock 1 3800’ VB @ vent building

VB @ exhaust duct

Fire @ exhaust ductbuilding duct duct

Injuries

Submerged Tube 1 3500’ VB @ in tube Chem@ in tube Fire @ in tube

Rock, C&C 1 3800’ VB @ in tunnel Chem@ intunnel Fire @ in tunnel

8 site assessments done, risk and reports in process. Note: not all tunnels in the program have risk assessment

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Note: not all tunnels in the program have risk assessment complete so they are not included in this table.

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TSA and USACE Evaluate Attack Scenarios for Highway Tunnels and Bridges

Questions??

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U.S. Army Corps of Engineers Protective Design Center

Questions??

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