National Academies Press: OpenBook

Risk-Based Construction Inspection: A Guide (2023)

Chapter: Chapter 2 - Understanding Current Inspection Practices

« Previous: Chapter 1 - Introduction
Page 7
Suggested Citation:"Chapter 2 - Understanding Current Inspection Practices." National Research Council. 2023. Risk-Based Construction Inspection: A Guide. Washington, DC: The National Academies Press. doi: 10.17226/27099.
×
Page 7
Page 8
Suggested Citation:"Chapter 2 - Understanding Current Inspection Practices." National Research Council. 2023. Risk-Based Construction Inspection: A Guide. Washington, DC: The National Academies Press. doi: 10.17226/27099.
×
Page 8
Page 9
Suggested Citation:"Chapter 2 - Understanding Current Inspection Practices." National Research Council. 2023. Risk-Based Construction Inspection: A Guide. Washington, DC: The National Academies Press. doi: 10.17226/27099.
×
Page 9
Page 10
Suggested Citation:"Chapter 2 - Understanding Current Inspection Practices." National Research Council. 2023. Risk-Based Construction Inspection: A Guide. Washington, DC: The National Academies Press. doi: 10.17226/27099.
×
Page 10
Page 11
Suggested Citation:"Chapter 2 - Understanding Current Inspection Practices." National Research Council. 2023. Risk-Based Construction Inspection: A Guide. Washington, DC: The National Academies Press. doi: 10.17226/27099.
×
Page 11
Page 12
Suggested Citation:"Chapter 2 - Understanding Current Inspection Practices." National Research Council. 2023. Risk-Based Construction Inspection: A Guide. Washington, DC: The National Academies Press. doi: 10.17226/27099.
×
Page 12
Page 13
Suggested Citation:"Chapter 2 - Understanding Current Inspection Practices." National Research Council. 2023. Risk-Based Construction Inspection: A Guide. Washington, DC: The National Academies Press. doi: 10.17226/27099.
×
Page 13
Page 14
Suggested Citation:"Chapter 2 - Understanding Current Inspection Practices." National Research Council. 2023. Risk-Based Construction Inspection: A Guide. Washington, DC: The National Academies Press. doi: 10.17226/27099.
×
Page 14
Page 15
Suggested Citation:"Chapter 2 - Understanding Current Inspection Practices." National Research Council. 2023. Risk-Based Construction Inspection: A Guide. Washington, DC: The National Academies Press. doi: 10.17226/27099.
×
Page 15

Below is the uncorrected machine-read text of this chapter, intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text of each book. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

7   To provide context for the optimization processes presented later in this guide, an implement- ing DOT should first identify the standard inspection program and acceptance protocols for materials and workmanship (i.e., including standard rigor and frequency) for salient work items or operations. These are typically captured in a standard inspector’s manual, inspection check- lists, a pay items list, or a schedule providing standard methods and frequencies of inspection and testing—sometimes referred to as an inspection and testing plan (ITP)—that can be adapted to each project. A DOT may also maintain its own inspection list if available. Figure 2.1 shows an example of an inspection activity in the comprehensive list developed for the Kansas DOT. 2.1 Construction Inspection Wight et al. defined a construction inspector as one whose primary responsibility is to verify that contractor work meets standards and specifications by observation and measurement. The definition can also be extended into a broader term that could include laboratory, survey, and office personnel involved in performing testing and processing payments to the contractor (Wight et al., 2017). DOTs guide inspection personnel in a variety of ways including the use of ITPs. Appendix A of NCHRP Research Report 838: Guidelines for Optimizing the Risk and Cost of Materials QA Programs (Hill International, Inc. et al., 2017) provides a summary of inspection practices in standard use and includes a section focusing on inspection. Five types of quality- related inspection are identified. The strategy and objectives for each type of inspection are described in Figure 2.2. Inspection types include Quality Control, Acceptance, Continuous Inspection of Work in Progress, Intermittent Inspection of Work in Progress, and Benchmark or End-Product Inspection. 2.1.1 Quality Checklists Checklists are useful tools for capturing all the key pass/fail quality inspections for an opera- tion or an attribute of the work that the inspector must check to ensure that it meets contract requirements. Checklists ensure that inspectors address all the key attributes of the work known historically to affect the quality and consistently inspect the work. Checklists are typically orga- nized by specification division. Many agencies are digitizing the inspection quality checklist using e-forms on a network server that an inspector can access in the field and fill out using a mobile device or field pad. An example of a quality inspection checklist for asphalt pavement construction is shown in Figure 2.3. Inspection activities are also captured in stand-alone field inspection manuals that include inspection quality checks for the standard construction program. C H A P T E R 2 Understanding Current Inspection Practices

8 Risk-Based Construction Inspection: A Guide Phase 1: Comprehensive list of KDOT inspection and testing activities No. Construction Division Section Activity Acceptance Inspection/test/ certificate/other Procedures 192 Division 600Flexible pavement CM - Part V 5.2.7.1 & SPECS 602.2 HMA quality control plan approval Other Documents review and approval for contractor’s HMA quality control plan 5.2.7.1 HMA: CONTRACTOR’S QUALITY CONTROL PLAN 1. quality control The contractor shall provide and maintain a QC plan that will assume all materials and products submitted to KDOT for acceptance will conform to the contract requirements. ` 602.2 HMA: CONTRACTOR’S QUALITY CONTROL REQUIREMENTS B. quality control plan At the preconstruction conference, submit to the Engineer for approval, a QC as outlined in section 5.7.2.1-HMA. KDOT Construction Manual KDOT Specifications Figure 2.1. Sample of developing inspection and testing activities (Source: Kansas DOT, 2014 and 2018). Inspection Method QA Strategy/Objectives Quality Control Inspection: Required inspection performed by the contractor during the production process to ensure that a material or product meets the contract requirements. Visual inspection of quality and workmanship during production or installation to ensure that a material or product meets contract requirements Acceptance Inspection: Inspection performed by the agency or designated agent to ensure that a product is acceptable in terms of the specifications for a specific project. Validate the quality of the product to ensure the proper combination of materials and details of construction Continuous Inspection of Work in Progress: Agency monitoring of the contractor’s construction processes on a continuous basis to ensure that the construction quality and workmanship comply with the plans and specifications. Provide the highest degree of confidence in the quality of workmanship and fitness for purpose (e.g., Inspect 80– 100% of the time work is in progress with assistant(s) assigned only to one operation) Intermittent Inspection of Work in Progress: Agency monitoring of the contractor’s construction processes on an intermittent basis to ensure that the construction quality and workmanship are in compliance with the plans and specifications. Provide a reasonable degree of confidence in the quality of workmanship and fitness for purpose (e.g., Inspect 30– 80% of the time work is in progress with assistant(s) assigned to two or three operations simultaneously) Benchmark Inspection: Agency inspection up to 30% of the time work is in progress, allowing construction operations to proceed until a predetermined critical activity or hold point has been reached. Provide some confidence in the quality of workmanship while minimizing disruption of construction operations Figure 2.2. Types and levels of inspection (Note: QA 5 quality assurance) (Source: Hill International, Inc. et al., 2017).

Understanding Current Inspection Practices 9   401 BITUMINOUS BASE AND PAVEMENT Date: Contractor: Contract: Route: Project: Item and Location: Bituminous Base and Pavement seY smetI .oN No N/A 1 Job mix formula approved? 2 Was subgrade released from previous inspections? 3 Is the laydown equipment the appropriate type, in working condition and adjusted properly? 4 Do the hauling trucks have tarps and clean beds? 5 Do the asphalt tickets have the appropriate information? 6 - Hold Point 7 Does the tack emulsion have an acceptable certification? 8 Have the begin/end tack quantity and temp been recorded? 9 Has the tack been applied at the specified rate? 10 Is the compacted mat thickness below the maximum allowed? 11 Have the cross slopes, thickness, and dimensions been verified? 12 Are the rolling methods and sequence appropriate? 13 Does the compacted mat appear uniform? 14 Is the mat density as specified? 15 Is the joint density as specified? 16 Have cores been taken according to random #s? 17 Have cores been taken at specified locations? 18 Have core holes been filled to restore the surface? 19 Have surface tolerances been determined using either straight edging or IRI? 20 Were existing pavement markings obliterated where necessary? Comments: QC Inspector Print Name: QC Inspector Signature: Company: Figure 2.3. Sample checklist (Note: IRI 5 International Roughness Index, QC 5 quality control) (Source: Missouri DOT Standard ITP, 2020).

10 Risk-Based Construction Inspection: A Guide 2.1.2 Inspection and Testing Plans Sampling and testing protocols vary across DOTs, but many have developed standard pub- lished schedules for field sampling and testing by specification division. Subpart B of 23 Code of Federal Regulations (CFR) 637 (23 CFR 637), outlines Quality Assurance (QA) Programs including six core elements of quality control, independent assurance, dispute resolution, per- sonnel qualification, and laboratory accreditation/qualification. Inspection and Testing Plans (ITP) range from a series of checklists for certain bid items that are typically listed in a DOT construction manual to robust, interactive automated documents that can vary depending on project type, complexity, and other variables. ITPs include both field observation of actual con- struction operations, such as monitoring lift thicknesses of earthwork, to field sampling and testing at prescribed frequencies, such as fresh concrete testing or testing embankment density. ITPs typically include descriptions of work items by division, acceptance methods (i.e., visual inspection, measurement, or testing), minimum frequencies for quality control (QC) or accep- tance, and required QC documentation. A comprehensive standard ITP for inspection and test- ing of flexible pavements maintained by Missouri DOT is shown in Figure 2.4. 2.1.3 Calculation of Quantities for Payment and Other Administration Responsibilities A common theme among DOT construction staff is that inspectors expend significant time verifying quantities for payment or performing other administrative activities. For example, inspectors may be tasked with performing detailed takeoffs for calculating quantities for pay- ment. Additional administrative activities assist with managing shorter-term project risks related to budget, schedule, construction work zone safety, and regulatory compliance. These include: • Progress validation • Change management • Environmental/permit compliance monitoring • Labor compliance (prevailing wage, OSHA [Occupational Safety and Health Administra- tion] certification, EEO [Equal Employment Opportunity], DBE [Disadvantaged Business Enterprise]) • Work zone safety and MOT (Maintenance of Traffic) An example field form for the calculation and measurement of quantities is shown in Figure 2.5. Construction inspection can be time-consuming for limited inspection staff, and some DOTs are evaluating how to reduce the time invested in documentation, especially for lower-risk activities where the inspector’s time might be optimized for higher priority items. Expanding the use of lump-sum items or payment of plan quantities rather than measuring actual quan- tities may offer better options for some pay items with little financial risk to either the DOT or the contractor. DOTs are also incorporating advanced technology and tools (e.g., mobile devices, 3D models, unmanned aerial systems [UASs], or drones for remote field observations) into inspection procedures. These tools can potentially save inspectors time and resources related to quality or quantity calculations and other administrative activities related to field inspection. Emerging technologies for inspection are addressed in Appendix C in terms of applicability, potential benefits and constraints, and additional resources to assist with implementation.

Item Description Parameter or Procedure Acceptance Criteria CRE2O Link (if applicable) 401 .5. .9. Aggregate Gradation & Deleterious Content Control and %AC QA Independent Samples Testing N/A N/A 1 test per 4 QC tests 401 .5. .8. .9. Aggregate Gradation Control QC and QA Split Samples Testing CRE2O - 400 1 per 1000 Ton, 1 per Day min 1 per 5 Days, 1 per Project min 401 .5. Deleterious Content Control QC and QA Split Samples Testing CRE2O - 400 1 per 5000 tons 1 per 5 Days, 1 per Project min 401 .5. Binder Content QC and QA Split Samples Testing CRE2O - 400 1 per 1000 Ton, 1 per Day min 1 per 5 Days, 1 per Project min 401 .5 .8 Recycled Asphalt Material (RAP) Gradation and AC Content T27, T164, T308 Testing CRE2O - 400 1 per 10,000 tons 1 per Project 401 .2.1 Aggregate Plasticity Index and Moisture Susceptibility T89 and T90, and T283 Testing N/A 1 per mix design 1 per mix per project 401 .5.4 Moisture Control Moisture Content gnitseT923T CRE2O - 400 1 at project start up and Week 1 per Week, 1 per Project min 401 .7.3 Subgrade Roadway Visual / measurement N/A 1 at start of day, 4 per day min 1 per Day 401 .8. Temperature Mixture Testing tcejorP rep 1yaD rep 4A/NtnemerusaeM02MT 401 .7.8 .8.4. Pavement Density and Coring of lifts gnitseT 661T / 14MT CRE2O - 400 1 per 500 Tons 1 per Week, 1 per Project min 401 .7.6 .8.4 Pavement Joints Density gnitseT 661T / 14MT CRE2O - 400 1 per Activity N/A 401 .10. Surface Tolerance Smoothness TM 59, Sec 610 Testing N/A N/A 1 per Activity 401 .12. Pavement Marking Visibility TM80, Sec 620 Testing N/A N/A 1 per ActivitySee Checklist - 620 Extraction or binder ignition. QC retains split samples See checklist - 200B Core locations by random #s Test prior to opening. See Checklist - 610 Additional testing if above design on fractions >10% passing #30 sieve Testing. Same Time as AC Content. Test any time moisture content changes. See EPG 460.3.14.4. M is c. CR E2 O Binder and Mix temperatures, see Sect 403.19.3 T164, TM54, T287, T308 TM20, Sec 209, Sec 407, Sec 408 Minimum Frequency QC Documents Contractor QC MoDOT QA Ch ec kl is t Te st R ec or d lanoitiddA .cepS Reference Section 401: Bituminous Base and Pavement Split samples within 5% of QC Split samples within 5% of QC T11, T27, TM 71 T11, T27, TM 71 T11, T27, TM 71 Asphalt Content Only applies for 200 tons or greater per day. This at the engineer's discretion. Core locations by random #s Test prior to opening. See Checklist - 401 See Checklist - 401 DIVISION 400: Flexible Pavements Properties Preparations Limitations Thickness minimum 1 per Figure 2.4. Sample ITP (Source: Missouri DOT Standard ITP, 2020).

12 Risk-Based Construction Inspection: A Guide 2.2 Optimization Strategies While DOTs have generally been able to meet inspection needs when faced with funding constraints, funding challenges have moved agencies toward making in-house staff reductions or using less experienced staff and outsourcing inspection responsibilities when managing larger construction programs or projects. To adapt to these constraints, some DOTs have implemented strategies to optimize inspection and increase efficiency. The typical strategies include reducing inspection and testing frequency based on the criticality of work or materials, using a contractor’s test results for acceptance, outsourcing QA to consultants, using alternative project delivery methods, using acceptance by certification, and combinations of these actions. Some DOTs have also developed more formal risk-based inspections to prioritize or optimize inspection resources. The rest of this chapter provides examples of strategies DOTs have implemented to optimize inspection and testing. 2.2.1 Criticality of Work or Materials Several DOTs (e.g., Indiana, Ohio, Virginia, Washington State, and Wisconsin) have devel- oped guides or manuals for prioritizing inspection resources based on the historic criticality of work, risks, or other factors. This section briefly discuss these manuals. The Wisconsin DOT (WisDOT) Construction Critical Inspection Manual (WisDOT, 2018) provides a tabulated listing sorted by specification reference for minimal inspection require- ments with the goal of preventing high-risk consequences of failure. It is not intended to address all activities required of the inspector, just the minimum requirements. The WisDOT Construc- tion and Materials Manual provides additional information. Specific major inspection activities before work begins and during work activities are described based on the following: • Priority based on the level of associated risk resulting from the insufficient inspection, • Levels of inspection defined as Continuous, Intermittent, and End Product, • Inspector experience, and • Inspection objective. The Virginia DOT (VDOT) Inspection Manual (VDOT, 2018) is intended to define and strengthen the application of construction inspection throughout the Commonwealth. The expected benefits are maximum productivity combined with appropriate inspector staffing. CA-D-2 Page of PROPOSAL LINE NO. Item No Description FROM TO 0 0 0 Checked By Date PLAN PAGE BUBBLE NO. PLAN QUANTITY MEASURED QUANTITY PAY QUANTITY EACH/LENGTH/TIME/LS Field Calculation and Measurement ALT ID (Project #) CONTID STATION LOCATION County/Route/Section Project # (Part Code) Offset TINUR/L DATE INITIALS Figure 2.5. Sample Quantity Calculation Form (Source: Ohio DOT, 2017).

Understanding Current Inspection Practices 13   The manual includes a series of tables sorted by items of work, including specification refer- ence number, inspection level, inspection objectives, and inspection activities describing the min imum inspection requirements of the major items of work. More specifically, the guide includes: • Levels of inspection are defined as Continuous, Intermittent, and End Product. • A minimum number of inspectors required is identified for some Continuous levels of inspection. • Inspection objectives are provided for each item, which may include compliance with plans and specifications, environmental controls, materials testing, and quantity computations. • Minimum inspector activities are described for different phases including activities before starting work, pre-installation or operations checks, and checks during installation or con- struction operations. • Approvals, notifications, and other post-construction checks are also identified. The Mississippi DOT (MDOT) Risk-Based Inspection and Material Testing Guide for Local Public Agency Projects (MDOT, 2020) is the result of MDOT’s effort to set baselines for hours of inspection and frequencies of testing for common types of local public agency projects based on risk levels for project components and pay items. MDOT also produced a companion Critical Inspection Guide (MDOT, 2020) for inspectors to prioritize inspection activities. The MDOT risk-based guide includes: • Local Public Agency Project Components are defined in terms of High, Moderate, and Low risk levels. • Inspection levels are defined as Full-Time, Part-Time, and Intermittent. • Project phases of work are identified and linked to pay item numbers. • Inspection hours are allotted based on inspection levels/frequency adjusted for seasonal impacts. • Materials QA is optimized by first rating the risk level by considering the failure type and the potential consequences of failure. • Materials property importance are then ranked based on their risk level (High, Moderate, and Low risk) to establish the required level of QA. • Optimal CE&I (Construction Engineering and Inspection) staffing levels are determined based on project type, inspection levels for the different phases/components of work, and the approved project schedule. The Indiana DOT (INDOT) sponsored research to develop a tiered prioritization system for inspection resources (Mostafavi and Abraham, 2012; Xu et al., 2019). The objectives of this project were to evaluate the current inspection practices of INDOT and develop an RBI protocol to facilitate the efficient allocation of limited inspection resources to activities with higher-risk consequences. The resulting protocol can be used to assist with the allocation of inspection resources when multiple activities are proceeding concurrently, and available resources are not sufficient to fully inspect all ongoing activities. The highlights of the results are listed below: • Construction activities were prioritized based on the perceived risk impacts due to reduced inspection by a panel of 101 experts from DOTs and consultants. • Activities were rated and tabulated as high, medium-high, medium, medium-low, and low priority. • Protocols for inspection of various construction activities were tabulated considering the priority, macro-consequences due to missed or reduced inspection, and critical items to be watched. • Inspection frequency was determined and classified as either randomly, frequently, or constantly.

14 Risk-Based Construction Inspection: A Guide 2.2.2 Use of Contractor Test Results Contractors have been taking on more sampling and testing responsibility in recent years. These responsibilities are associated with the use of statistically based QA specifications and alternative project delivery methods that place more performance risk on the industry. Including contractor QC data in the acceptance decision allows for some optimization of DOT resources— even if, overall, the testing effort is not reduced. In recognition of the increasing role played by industry in assuring materials quality, FHWA’s sampling and testing regulation, QA Practices for Construction, published as Title 23, Code of Federal Regulations, Part 637 (23 CFR 637) was revised in 1995 to expressly allow the use of contractor QC test results in a DOT’s acceptance decision provided that: • The sampling and testing are performed by qualified laboratories, using qualified sampling personnel. • The DOT, or its designated agent (i.e., consultant under direct contract with the DOT), vali- dates the contractor’s test results by performing some level of independent verification sam- pling and testing. The use of a third-party testing and inspection firm hired by the contractor does not relieve the agency of its responsibility for verification. Likewise, splits of contractor- obtained samples cannot be used for verification purposes unless independently validated by the DOT. The independent validation requires that the DOT use its half of a contractor- obtained split sample to compare with independently sampled contractor QC tests. • The QC sampling and testing are evaluated under an independent assurance (IA) program. • The DOT has a dispute resolution system in place to resolve possible discrepancies between the contractor’s QC and the agency’s verification data. The DOTs are expected to perform enough verification sampling and testing to be able to identify statistically valid differences between its results and those of the contractor. [The F-test (comparison of vari- ances) and t-test (comparison of means) are commonly used together to validate contractor test data.] While there is no universally accepted standard, a minimum rate of 10% of the contractor’s testing rate has been suggested as a rule of thumb. The FHWA Tech Brief Construc- tion Quality Assurance for Design-Build Highway Projects (FHWA- HRT-12-039) (FHWA 2012) does acknowledge that rates of verification may differ based on the risks involved and offers as an example that structural concrete would likely require more verification testing than embankment materials. As noted in the Tech Brief, if QC test data are to be included in the agency acceptance decision, the QC data must be validated by agency verification test results. Lot and sublot sizes, sam- pling and testing methods, and sampling locations must be specified for each critical quality characteristic that will be verified by the agency. Acceptable quality levels and a statistically valid number of tests should be specified to minimize the likelihood of accepting deficient materials (buyers’ risk) or rejecting acceptable materials (sellers’ risk). 2.2.3 Small Quantity Acceptance Several DOTs allow inspection and testing requirements to be waived or adjusted for small quantities of materials. For example, the Washington State Department of Transportation (WSDOT) provides project engineers with substantial latitude to adjust testing frequencies (WSDOT, 2013). Project engineers may choose to accept small quantities of materials without For additional information related to the use and validation of contractor test results refer to: • FHWA Technical Advisory T6120.3 (Use of Contractor Test Results in the Acceptance Decision, Recommended Quality Measures, and the Identification of Contractor/Department Risks) issued on August 9, 2004. • FHWA Tech Brief Construction Quality Assurance for Design-Build Highway Projects (FHWA-HRT-12-039) issued in April 2012.

Understanding Current Inspection Practices 15   meeting the minimum sampling and testing frequencies (e.g., by visual inspection, certification, or other methods) if the proposed quantity for that material is less than the minimum required quantity. 2.2.4 Large Quantities Under Control DOTs will generally allow project engineers some discretion to reduce the frequency of sam- pling for high-volume materials once initial testing has verified that the materials supply is relatively uniform or statistically under control and within specification limits. However, DOTs typically reserve the right to focus and increase QA testing if the situation suggests that the pro- cess is somehow changing and is not consistently under control. For projects with large quantities or volumes of materials, WSDOT’s policy is that it may choose to reduce sampling frequency or eliminate selected test properties after ten consecutive samples taken at the standard testing frequency are shown to be within the specification limits. If there are any failing tests, the sampling and testing frequency will revert to the normal schedule. 2.3 Summary To understand the current state of inspection and testing and determine how to optimize, the first step is to identify all the current construction inspection requirements that are included in the construction program. In addition to quality inspections, these responsibilities may include the measurement of quantities for progress payments; environmental, permit, and labor compli- ance; safety and traffic monitoring; and other administrative activities. Risk-based inspection should consider strategies to reduce less critical inspection items allowing for an increased focus on more critical inspection activities. Subsequent chapters of this guide focus on describing a flexible RBI framework that DOTs may apply to determine how to allocate their inspection resources more efficiently.

Next: Chapter 3 - Risk Assessment to Determine Priority of Inspections and Acceptance Methods »
Risk-Based Construction Inspection: A Guide Get This Book
×
 Risk-Based Construction Inspection: A Guide
MyNAP members save 10% online.
Login or Register to save!
Download Free PDF

Due to budget cuts and reduced experience levels of inspectors and engineers, state departments of transportation (DOTs) have implemented risk-based strategies to achieve greater efficiency in construction inspection. These strategies include prioritizing inspection based on inherent risks related to construction operations, using emerging technology applications to save time, and accepting certification and contractors' test results to offset shortages of experienced inspection resources.

NCHRP Research Report 1039: Risk-Based Construction Inspection: A Guide, from TRB's National Cooperative Highway Research Program, discusses the importance of construction inspection and aims to assist state DOTs and the U.S. Federal Highway Administration in meeting quality standards.

Supplemental to the report are NCHRP Web-Only Document 344: Risk-Based Construction Inspection: Conduct of Research Report and an Inspection Risk Assessment Questionnaire.

READ FREE ONLINE

  1. ×

    Welcome to OpenBook!

    You're looking at OpenBook, NAP.edu's online reading room since 1999. Based on feedback from you, our users, we've made some improvements that make it easier than ever to read thousands of publications on our website.

    Do you want to take a quick tour of the OpenBook's features?

    No Thanks Take a Tour »
  2. ×

    Show this book's table of contents, where you can jump to any chapter by name.

    « Back Next »
  3. ×

    ...or use these buttons to go back to the previous chapter or skip to the next one.

    « Back Next »
  4. ×

    Jump up to the previous page or down to the next one. Also, you can type in a page number and press Enter to go directly to that page in the book.

    « Back Next »
  5. ×

    To search the entire text of this book, type in your search term here and press Enter.

    « Back Next »
  6. ×

    Share a link to this book page on your preferred social network or via email.

    « Back Next »
  7. ×

    View our suggested citation for this chapter.

    « Back Next »
  8. ×

    Ready to take your reading offline? Click here to buy this book in print or download it as a free PDF, if available.

    « Back Next »
Stay Connected!