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DIB 83-02 - 3.1 Problem Identification and Assessment
DESIGN INFORMATION BULLETIN No. 83-02
CALTRANS SUPPLEMENT TO FHWA CULVERT REPAIR PRACTICES MANUAL
|3.1 PROBLEM IDENTIFICATION AND ASSESSMENT|
In 2005 Caltrans Division of Maintenance implemented a statewide culvert inspection program. In addition to those culverts classified as bridges (see Index 62.2 (2) of the HDM) and inspected at least every two years, a systematic evaluation of condition was implemented for all other culverts. The Project Engineer should coordinate all culvert inspection with their local maintenance personnel specifically resourced to perform culvert inspection and maintain a database by the culvert inspection program.
Over the years, culverts have traditionally received less attention than bridges. Since culverts are less visible it is easy to put them out of mind, particularly when they are performing adequately. Safety is the most important reason why culverts should be inspected.
There are several key activities that must always be performed during a culvert inspection to ensure that a culvert is functioning adequately. The inspection should evaluate structural integrity, hydraulic performance and roadside compatibility. It is important to determine the underlying cause of a problem so that it will not recur or become more serious.
The FHWA Culvert Inspection Manual (refer to on-line FHWA Hydraulics publications: http://www.fhwa.dot.gov/bridge/hydpub.htm ) provides guidelines for the inspection and evaluation of existing culverts. Although it is a stand-alone supplement to the bridge inspector’s training manual, the guidelines are generally applicable to culverts of all sizes and it is recommended as the primary inspection reference by Caltrans staff for all culvert inspection.
Refer to Appendix C for an example of Caltrans Condition tables developed for the culvert inspection program and used by Maintenance. The rating system developed by Caltrans is in lieu of the FHWA rating system and is compatible with the Caltrans Culvert Inventory database.
A complete version of the Caltrans Condition tables that were developed for the pilot culvert inspection program along with a list of information used to program the field data collecting units can be accessed at: http://www.dot.ca.gov/hq/oppd/culvert/index.htm
Contact Headquarters Maintenance for more information on the pilot culvert inspection program.
The following general elements are recommended to consistently determine cause, type, and extent of culvert problems:
a) Review available information: Roadway and culvert Design, ADT/Truck Traffic, Maintenance History, Design Q – Headwater/Velocity, pH of water and soil, Resistivity of soil, Water Table.
b) Observe overall condition.
c) Inspect approach roadway, pavement and embankment based on their interaction with the culvert and end treatments.
d) Inspect upstream and downstream waterways based on their interaction with the culvert and end treatment. The inspection should include an assessment of the vegetation, slope, and type of water system, scour, high water marks, changes in drainage area and land-use.
e) Assess the condition of the end treatment and appurtenant structures including their ability to pass flows.
f) Assess the condition of the culvert barrel by inspecting joints, the degree of deterioration of the culvert material, deformation, alignment, and the culverts ability to pass its design flow.
For long pipes 24 inches or smaller in diameter, it will probably be necessary to perform an inspection of the barrel with a remote controlled video camera. All Districts have a remote camera.
Remote controlled camera Vehicle
District 3 Video inspection vehicle (above)
The camera system is also used to respond to Maintenance requests for investigation, which may lead to Capital Projects. If available, this unit may be utilized during project construction for investigating the quality of joints, backfill operations, or other needs
The uses may
vary from district to district.
The following references discuss problem identification and assessment:
- FHWA Culvert Inspection Manual (refer to on-line FHWA Hydraulics publications: http://www.fhwa.dot.gov/bridge/hydpub.htm ) provides guidelines for the inspection and evaluation of existing culverts. Although it is a stand-alone supplement to the bridge inspector’s training manual, the guidelines are generally applicable to culverts of all sizes and it is recommended as the primary inspection reference by Caltrans staff for all culvert inspection.
- Chapter 3, FHWA Culvert Repair Practices Manual Volume 1, and Table 7.1 on page 7-5. See Figures 3.2, 3.3 and 3.4 on pages 3-9, 3-10 and 3-12 for flow charts outlining the overall process for analysis of problems and solutions.
- Culvert Assessment and Decision-Making Procedure Manual, for Federal Lands Highway – 2010. http://www.cflhd.gov/programs/techDevelopment/hydraulics/culvertassessment/index.cfm
This page last updated August 20, 2011