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DIB 83 - 1.1 Introduction
DESIGN INFORMATION BULLETIN No. 83-02
CALTRANS SUPPLEMENT TO FHWA CULVERT REPAIR PRACTICES MANUAL
|1.1.3 Overview of Problem|
Numerous documents and publications have already been written on the issue of culvert repair. The primary purpose of this Design Information Bulletin (D.I.B.) is to supplement the 1995 Federal Highway Administration Publication ‘Culvert Repair Practices Manual-Volumes 1 and 2’ (refer to on-line FHWA Hydraulics publications: http://www.fhwa.dot.gov/bridge/hydpub.htm ), highlight areas of general concern, and reference other appropriate documentation to provide information, guidelines and alternatives for the cost-effective repair, rehabilitation, strengthening or retrofit upgrade of culverts and storm drains as described in Indices 806.2 and 838.1 of the Highway Design Manual (HDM). In addition, information contained in this D.I.B. supersedes D.I.B. No. 76 “Culvert Rehabilitation using Plastic Pipe Liners” dated January 1, 1995.
This D.I.B. is intended to be of assistance to design, maintenance, hydraulic and structural engineers who are responsible for decisions regarding maintenance, repair, rehabilitation, retrofit upgrading, and replacing highway culverts.
Many new products and techniques have been developed that often make complete replacement with open cut unnecessary. When used appropriately, these new products and techniques can benefit the Department in terms of increased mobility, cost, and safety to both the public and contractors. This D.I.B. is intended to build a collection of procedures that are cost-effective for their location and that will meet the needs of their particular area.
This D.I.B. is organized into twelve sections:
Index 1.1 provides an introduction, purpose, target audience, and a general overview of problem.
Index 2.1 reviews the most common materials used in culvert conduits and associated Highway Design Manual (HDM) references for material selection and service life. It provides general discussions on the behavior of rigid and flexible pipe and references the appropriate Caltrans standards for excavation, backfill and installation. Service life for culvert rehabilitation is also discussed in conjunction with various geotechnical factors, which include: pH, resistivity, chloride and sulfate concentration of the surrounding soil and water, and abrasion potential.
Index 3.1 discusses problem identification and assessment through field inspection.
Index 4.1 outlines culvert end treatment and other appurtenant structure repairs and retrofit improvements for headwalls, endwalls, wingwalls and outfall works.
Index 5.1 outlines various types of problems that can be encountered in culvert barrels and presents guidelines and information on procedures for the associated repairs.
Index 6.1 provides information on general culvert rehabilitation techniques. This section discusses Caltrans host pipe structural philosophy, grouting voids and provides a comprehensive outline of the various rehabilitation families and techniques.
Index 7.1 discusses the following influencing factors that should be considered: hydrology, hydraulics, safety, environmental, host pipe dimensions and irregularities, and headquarters assistance/approval for large diameter plastic liners and pipe replacement using Trenchless Excavation Construction (TEC) methods.
Index 8.1 provides a summary table and references for comparison of the various alternative rehabilitation techniques and guidance on the overall process.
Index 9.1 discusses replacement; the decision process used to determine whether to repair or replace. Open cut and a comprehensive listing of the various trenchless replacement systems are provided, along with other considerations for TEC.
Index 10.1 discusses Caltrans New Product Approval Process and construction evaluated experimental feature program and appropriate headquarters contacts.
Index 11.1 Identifies some other considerations that should be taken into account when analyzing alternatives to repair and/or replace culverts.
Index 12.1 provides supplemental information on; butt fusion procedures, Caltrans New Product Approval Process, culvert inspection, corrosion and crack repair in concrete pipe. Also provided are sources of repair information, industry contacts, cured in place pipe (CIPP) guidance for resident engineers, and some large diameter metal pipe repair case studies.
Culverts are an integral part of the highway system, and like other parts of the system they are subject to deterioration. Currently, culverts functionally classified as bridges (see Index 62.2 (2) of the HDM) are inspected at least every two years. In 2005 the Department initiated a statewide culvert inspection program resourced through maintenance. Camera equipped vehicles for culvert inspection are available in every District. See Index 3.1.1. However, culvert repair work is frequently approached strictly as a maintenance problem without consideration of the underlying structural or hydraulic conditions from which the deterioration originates. Surveys performed recently have shown relatively high percentages of culverts in need of at least some form of repair.
Because of the large number of aging culverts in use today, the Department is faced with a major expense in repairing, rehabilitating, and replacing culverts as they reach the end of their design service life.
To date, there has been limited written guidance available within the Department on the topic of how to rehabilitate culverts without disrupting traffic.
This page last updated August 20, 2011