Project Objective

The objectives of this study are: * Identify and recommend scour countermeasures for both existing and new bridges, * Standardize the identified scour countermeasure technologies; provide standard details and drawings, construction procedures, and design technologies for use by bridge designers, * Develop guidelines in the form of a New Jersey Scour Countermeasures Handbook. The Handbook will contain identified scour countermeasures, standard details, and practical cost ? benefit relationships for New Jersey structures, stream geometry, stream soil conditions, environmental constraints and feasibility.

Project Abstract

Bridge engineers are presented with numerous typical and non-typical sour countermeasure designs for application to scour critical bridges. A wide variety of countermeasures are presented in the publications to control channel instability and to mitigate scour at foundations of abutments and piers. Some widely used countermeasures include: foundation strengthening, sheet piles, concrete apron walls, curtain walls, sacrificial piles and pier modifications. Additional widely used technologies include impermeable spurs, drop structures, retards, riprap, grouted riprap and grout filled bags. Some State highway agencies have worked with articulated blocks, grouted riprap, and gabion mattresses.

This research will focus on the identification of additional technologies and structural solutions, which are applicable for New Jersey structural applications, stream geometry, stream soil conditions, environmental constraints and feasibility (physical restrictions). Economic, cost effective technologies of countermeasures will be determined to match New Jersey resources and scour countermeasures for both existing structures and new bridge construction. Practical, cost effective technologies for New Jersey will be the primary focus for the identification of additional technologies.

The identified technologies will be presented in the form of guidelines for the design, construction and use of scour countermeasures. A New Jersey Scour Countermeasures Handbook will be presented for the selection of appropriate applications for the variety of scour conditions, which are encountered in New Jersey. The Handbook will contain selected permanent scour countermeasures for identified scour critical bridges, and guidelines for application, design and construction. The practical guidelines will assist engineers in the selections of appropriate technologies to facilitate the overall design.

Task Descriptions

Phase I - Literature Search Although the principal investigator and co-principal investigators have a significant background in bridge scour countermeasures, stream hydraulics, and soils, a preliminary literature search was conducted to develop this proposal. In addition to this search, an in-depth search will include national and international sources, proprietary sources, and other State DOT and highway agencies as well as publications from special journals and conferences. The search will concentrate on existing, established and new technologies for specific scour conditions in New Jersey and costs of these technologies related their function for scour mitigation. The search will consider mathematical modeling techniques, construction practices and a review of the FHWA Hydraulic Engineering Circulars. The search will also include construction details and specifications for future development of NJDOT Construction Specifications.

Deliverables: The research team will present the findings from the in-depth literature search to the Research Project Selection and Implementation Panel for a discussion of the appropriate research approach. With the guidance of the panel, the research team will make recommendations for appropriate technologies for further analysis. The presentation will include a literature search report to document Phase I. The research team will provide quarterly progress reports and provide expertise to NJDOT engineers, as required, during the literature search.

Phase II - Research Approach Task 1: Analysis of Scour Countermeasures After meeting with the Research Project Selection and Implementation Panel, a Research Approach will be formulated to analyze, select countermeasure technologies, determine guidelines for the cost effectiveness of scour countermeasures, and preparation of the Handbook of Scour Countermeasure Design. The analyses of scour countermeasures for the protection of highway structures are affected by stream stability, and the form and pattern of the stream. The analyses procedures that are outlined in Hydraulic Engineering Circular HEC-23 will be the basis for this study. Task 2: Selection of Scour Countermeasures and Procedures The selection of scour countermeasures and the procedures for that selection will follow the mechanisms that are described in Highways in the River Environment (HIRE) and Hydraulic Engineering Circulars. The selection procedure and decision matrix will be developed from the literature search and participation from the Research panel. The matrix will include stream type and size, streambed radius, flow velocity and type of soils, debris estimates, bank conditions and flood plain information as well as functional applications. Initial and maintenance costs will be an integral component of the matrix and selection procedure. Also, countermeasures will be considered for stream meander migration, channel braiding, degradation and aggradations, as well as countermeasures for bridge scour. The selection of appropriate technologies for the Handbook will be determined with the cooperation of the NJDOT, Research Project Selection and Implementation Panel . Task 3: Implementation and Guidelines Development Following the direction of the Research Panel and the selection procedures, which were established in the tasks above, guidelines, will be developed to assure uniformity in scour countermeasure designs and adherence to NJDOT construction practices. The guidelines will include a description of the scour countermeasure and its technology, diagrams showing the countermeasure and its application, mathematical expressions for the hydraulic design, stability analysis, and there applications to the design procedure including the selection of factors of safety, and construction and installation practices.

The constructions guidelines will provide design source and manufacturers? recommendations with appropriate design expressions, and the experience of other DOTs including problems encountered with the specific design and scour countermeasure. Specifications will be provided for testing when applicable, with AASHTO or ASTM specifications. The guidelines will contain information for the implementation of the research findings into NJDOT practices. A list of reference will be provided for additional information and case histories for additional resources.

Task 4: Final Reporting and Handbook Preparation The research team will prepare a final report, which will summarize and document the literature search and tasks, and prepare the NJDOT Handbook of Scour Countermeasure Designs, which will show selected countermeasures, design information, selection procedures, and technologies for application to NJDOT structures. A training course and presentation package with a PowerPoint presentation will be prepared for the implementation and training of NJDOT engineers and consultants. The Handbook will contain the selection matrix, tables, diagrams, charts and graphs of appropriate countermeasures. The final reporting will be completed according to the requirements in the NJDOT, Division of Research and Technology, Guidelines for Preparing Research Final Reports and Tech Briefs.

Budget

$184,498

Student Involvement:

This project will involve several undergraduate, graduate and doctoral students in data collection, presentations, literature documentations and report preparation.

Relationship with Other Research Activities:

None

Technology Transfer Activities

The research team will prepare the training course and presentation package with a PowerPoint presentation for the implementation of the study findings and training of NJDOT engineers and consultants. At the discretion of the Research Panel, the training course and presentation package with the Handbook as the central point will be presented to Regional Engineers and Central office engineers. The research team will provide the resource materials for the training courses. In addition to the above, the Research team will be available during and after the completion of the project to provide expertise and advice to designers and construction engineers for the implementation and use of the scour countermeasures on bridge construction projects.

Benefits of the Project

The results of this research will identify and recommend permanent scour countermeasures for both existing and new bridges, standardize the identified scour countermeasures technologies; provide standard details and drawings, construction procedures, and design technologies for use by bridge designers. From these results guidelines in the form will be developed for a New Jersey Scour Countermeasures Handbook. The Handbook will contain identified scour countermeasures, standard details, and practical cost ? benefit relationships for New Jersey structures, stream geometry, stream soil conditions, environmental constraints and feasibility. Technical memorandums will be prepared for the Literature Search, Analysis of Scour Countermeasures, the Selection of Scour Countermeasures and Procedures, and Implementation and Guidelines Development. A final report will document the results of the study. Course materials will be developed for the implementation and training of NJDOT engineers.

Key Words

Scour, piers, abutments, bridges