NHI – Stream Stability and Scour at Highway Bridges

COURSE DESCRIPTION:

The National Highway Institute’s (NHI) 3-day Stream Stability and Scour at Highway Bridges course provides participants with comprehensive training in the prevention of hydraulic-related bridge failures. Course participants will receive training in conducting a stream stability classification and qualitative analysis of stream response and make estimates of scour at a bridge opening.

Material for the course comes primarily from two Hydraulic Engineering Circulars (HEC), “Evaluating Scour at Bridges” (HEC-18), 5th Edition (2012), and “Stream Stability at Highway Structures” (HEC-20), 4th Edition (2012). The effects of stream instability, scour, erosion, and stream aggradation and degradation are covered. Quantitative techniques are provided for estimating long-term degradation and for calculating the magnitude of contraction scour in a bridge opening. Procedures for estimating local scour at bridge piers and abutments for simple and complex substructures are also provided. A comprehensive workshop integrates qualitative analysis and analytical techniques to determine the need for a Scour Plan of Action for correcting stream instability and scour problems. For this 3-day course, the host agency will need to select 3 optional topics (out of 8 possible topics). Course instructors will contact the host prior to the course to complete a pre-course questionnaire, determine optional topics to be taught, and discuss the course schedule.

This comprehensive training provides preventive techniques for identifying, analyzing, and calculating various hydraulic factors that impact bridge stability. Public and private sector engineers responsible for maintaining the integrity of highway bridges will find it invaluable.

Prior to the beginning of the course, participants are strongly encouraged to enroll in the following Web-based training (WBT) courses: 135091 Basic Hydraulic Principles Review, 135086 Stream Stability Factors and Concepts, and 135087 Scour at Highway Bridges: Concepts and Definitions. Mastery of the concepts covered in these WBTs will enhance participation in the Instructor-led training.

OUTCOMES:

Upon completion of the course, participants will be able to:

• Identify indicators of stream instability that can threaten bridges
• Identify stream types and their potential for instability problems
• Describe open-channel hydraulics concepts in bridge scour and stream instability analyses
• Define types of scour that can occur at bridge crossings
• Describe aggradation, degradation, and contraction scour
• Calculate contraction scour for live bed and clear water conditions
• Describe factors that influence scour at piers
• Calculate pier scour for three typical case studies
• Describe the factors that influence scour at abutments
• Describe how HEC-18, HEC-20, and HEC-23 provide analysis procedures for stream instability and bridge scour
• Perform Level I and II analyses
• Classify a stream using two different classification systems
• Conduct a qualitative analysis of stream responses
• Apply the HEC-18 scour equations to determine total scour at a bridge
• Determine the need for a Scour Plan of Action at a scour-critical bridge