The National Academies Press

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From page 1... ... This part of the field manual provides background information helpful for performing evaluations of highway structures during emergency situations. The chapters comprising the background are the introduction, the overview of highway structure safety evaluation, the Preliminary Damage Assessment guidelines, and an overview of emergency events. Read the entire page →
From page 2... ... Part I: Background 3 Introduction 1 Introduction 1.1 Purpose and Scope This report volume is a field reference manual to be used for assessing, coding, and marking of highway structures during emergency situations. Highway structures include bridges, tunnels, culverts, walls, embankments, and overhead signs. Read the entire page →
From page 3... ... Part I: Background 4 Introduction emergency events. Part II (Chapters 5 through 9) Read the entire page →
From page 4... ... Part I: Background 5 Introduction 1.3.3 Marking Classifications A final marking classification shall be assigned to each structure indicating appropriate usage during and following an emergency event. Refer to Section 2.3 for more detailed definitions. Read the entire page →
From page 5... ... Part I: Background 6 Overview of Highway Structure Safety Evaluation 2 Overview of Highway Structure Safety Evaluation 2.1 Assessment Stages The four distinct procedures that can be performed in the assessment of highway structures during emergency situations are briefly described in the following list; an estimated inspection time per highway structure is also provided. • Fast Reconnaissance (within 4 to 6 hours) Read the entire page →
From page 6... ... Part I: Background 7 Overview of Highway Structure Safety Evaluation 2.2 Response Levels Response levels relate to the immediacy of the needed response, and the level of resources/ effort that will be needed during an emergency event. Actions associated with response levels are initiated when the ME has determined that it is safe to begin. Read the entire page →
From page 7... ... Part I: Background 8 O verview of H ighw ay Structure Safety Evaluation PDA LIMITED USE UNSAFE DDA UNSAFE INSPECTED EI Repair/ Rebuild INSPECTED UNSAFE (Partial/Full Collapse) Emergency Situation Primary Scope of NCHRP Project INSPECTED Preparation UNSAFE = The structure requires further evaluation in the next assessment stage prior to being open to traffic. Read the entire page →
From page 8... ... Part I: Background 9 Overview of Highway Structure Safety Evaluation 2.3 Coding and Marking System A coding and marking system was developed to support uniform communication between inspectors, maintenance crews, engineers, and others as necessary. All inspected structures within the affected region should be marked both physically (in the PDA phase) Read the entire page →
From page 9... ... Part I: Background 10 Overview of Highway Structure Safety Evaluation PDA, it will be further evaluated using DDA. During DDA, highway structures are marked with one of three decals on a new/updated placard: INSPECTED, LIMITED USE, or UNSAFE (refer to Figure 2-1) Read the entire page →
From page 10... ... Part I: Background 11 Overview of Highway Structure Safety Evaluation 2. Affix the placard using metal clips or wire. Read the entire page →
From page 11... ... Part I: Background 12 Overview of Highway Structure Safety Evaluation 2.4 Use of Judgment Required The use of judgment is essential in the assessment of damaged highway structures, both for personal safety as well as safety of the general public. This section will address both of these. Read the entire page →
From page 12... ... Part I: Background 13 Preliminary Damage Assessment 3 Preliminary Damage Assessment Each PDA team will be assigned to a route with a list of structures to assess. Due to the unpredictable nature of emergency events, it is important to be flexible as changes to planned routes may occur as more information becomes available. Read the entire page →
From page 13... ... Part I: Background 14 Preliminary Damage Assessment and lifeline route designation. Although these structures should be opened as soon as possible to the public, in the event of any questionable damage, they should be marked as UNSAFE. Read the entire page →
From page 14... ... Part I: Background 15 Preliminary Damage Assessment worth noting during PDA as they may result in the structure being weakened. Such damage should also be considered when making a final call for the structure posting (INSPECTED or UNSAFE) Read the entire page →
From page 15... ... Part I: Background 16 Preliminary Damage Assessment 10. PDARs look for evidence of disturbance or irregularities -- such as shifts in guardrails or striping -- and note these on the form. Read the entire page →
From page 16... ... Part I: Background 17 Preliminary Damage Assessment 2. When element damages are not clear, provide comments that supply sufficient information to understand the observed damage state. Read the entire page →
From page 17... ... Part I: Background 18 Preliminary Damage Assessment bearing support, extensive cracking and spalling of culvert wingwall, very large column shear cracks propagating into concrete core) Read the entire page →
From page 18... ... Part I: Background 19 Preliminary Damage Assessment 3.6.2 Recommended Field Inspection Supplies for PDA Structures within a transportation network pose uncertain dangers to inspection personnel, especially after a major event. PDA tools and equipment for inspection, protection, emergency protocols, and safety gear should be in place. Read the entire page →
From page 19... ... Part I: Background 20 Overview of Emergency Events 4 Overview of Emergency Events 4.1 Overview This chapter provides an overview of common damages and possible modes of failure for each emergency event. These tables do not cover all types of damages expected. Read the entire page →
From page 20... ... Part I: Background 21 Overview of Emergency Events Table 4-2. Damage matrix in terms of emergency event types and highway structures. Read the entire page →
From page 21... ... Part I: Background 22 Overview of Emergency Events peak ground acceleration, peak ground velocity, and spectral acceleration. A list of common damages resulting from earthquakes is highlighted in Table 4-3. Read the entire page →
From page 22... ... Part I: Background 23 Overview of Emergency Events 4.5 Tornado and High Winds One of the most damaging aspects of tornados in regard to highway structures is impact from debris. High speed winds can affect low weight structures such as overhead signs. Read the entire page →
From page 23... ... Part I: Background 24 Overview of Emergency Events 4.7 Flooding Flooding is generally divided into three load cases: hydrostatic loads, hydrodynamic loads, and impact loads. The hydrostatic loads are both vertical (buoyant) Read the entire page →
From page 24... ... Part I: Background 25 Overview of Emergency Events 4.9 Scour Flooding events can compromise the safety of bridges susceptible to scour. In the event of hydro-hazard events all scour-susceptible bridges should be monitored. Read the entire page →
From page 25... ... Part I: Background 26 Overview of Emergency Events The following structures should be monitored for any of the following conditions: • Bridge – Pressure flow (bridge deck is fully or partially submerged) – Water overtopping the bridge – Misalignment, settlement, or tilt damage – Vertical or lateral displacement of the superstructure – Excessive vertical or horizontal separation at bridge deck joints – Clear sign of structural distress • Approach Roadway – Settlement damage – Water overtopping the approach roadway – Embankment erosion damage • Waterway Channel – Significant debris buildup or formation of damming – Streambed has lowered to the scour-critical elevation at pier or abutment – Water surface elevation has risen to the bridge closure water surface elevation level when such markings have been determined for a bridge. Read the entire page →

From page 1...

... This part of the field manual provides background information helpful for performing evaluations of highway structures during emergency situations. The chapters comprising the background are the introduction, the overview of highway structure safety evaluation, the Preliminary Damage Assessment guidelines, and an overview of emergency events.