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Following are explanations of some useful documents. You need to know that these documents exist.
NCHRP 350 is an acronym for National Cooperative Highway Research Program (NCHRP) Report 350, "Recommended Procedures for the Safety Performance Evaluation of Highway Features".
NCHRP 350 contains guidelines for testing of traffic devices. FHWA policy requires that devices used on the National Highway System be successfully tested in accordance with these guidelines. Caltrans often requires additional information and testing from a manufacturer before a device can be used on California projects.
Results of NCHRP 350 testing are summarized by award of a "Test Level": Test Level 1, 2, or 3. Criteria for test levels for device types differ and are specified in NCHRP 350, but by summarizing results as TL-1, TL-2, or TL-3, there is a consistent and quickly understandable level of acceptance across all types of devices.
Full-scale impact testing is the most common method of evaluating the safety performance of guardrails, median barriers, bridge railings, crash cushions, breakaway supports, truck-mounted attenuators, work zone traffic control devices, and other hardware. NCHRP 350 provides uniformity in the procedures and criteria used to evaluate these traffic devices.
The types of hardware that are tested and evaluated using NCHRP 350 Report criteria and the location of their federal acceptance letters are:
- Longitudinal Barriers -- http://safety.fhwa.dot.gov/roadway_dept/road_hardware/longbarriers.htm. Also includes some Bridge Rails, Bridge Rail Transitions, and Guardrail Offset Blocks.
- Barrier Terminals and Crash Cushions -- http://safety.fhwa.dot.gov/roadway_dept/road_hardware/term_cush.htm.
- Bridge Railings -- http://safety.fhwa.dot.gov/roadway_dept/road_hardware/bridgerailings.htm.
- Breakaway Hardware -- http://safety.fhwa.dot.gov/roadway_dept/road_hardware/breakaway.htm.
- Work Zone Devices -- http://safety.fhwa.dot.gov/roadway_dept/road_hardware/wzd.htm.
Evaluation factors include:
- Structural adequacy -- vehicle redirection, controllled penetration, or controlled stopping;predictable operation.
- Occupant risk -- detached elements, upright vehicle during and after impact, occupant impact velocities and ridedown accelerations.
- Vehicle trajectory -- intrusion into adjacent lanes, occupant impact velocity, exit angle, and vehicle trajectory after impact.
Acceptance letters also include:
- Description of device.
- Basic useage guidelines.
For more information on NCHRP 350, please go to the following web site: http://safety.fhwa.dot.gov/roadway_dept/road_hardware/nchrp_350.htm.
Caltrans Approved Products List
For a list of all Caltrans approved products, please go to: http://www.dot.ca.gov/hq/esc/approved_products_list/. Barriers and attenuators are on the Highway Safety Features page.
Manual on Uniform Traffic Control Devices (MUTCD)
Besides testing, the FHWA also defines standards for using traffic control devices on all streets and highways (not just on the National Highway System.) These standards are contained in the Manual on Uniform Traffic Control Devices, or MUTCD.
The most current edition is MUTCD is the 2003 Edition with Revision Number 1 Incorporated, dated November 2004. HTML and PDF formated versions are available online at http://mutcd.fhwa.dot.gov/kno-2003r1.htm. It is also available locally at Documents.
Caltrans has adopted the California Manual on Uniform Traffic Control Devices (FHWA's MUTCD 2003 Revision 1, as amended for use in California), also variously called the "California MUTCD" or "California Supplement," to prescribe uniform standards and specifications for all official traffic control devices in California.
The California Supplement is available in part and in whole at http://www.dot.ca.gov/hq/traffops/signtech/mutcdsupp/supplement.htm. It is also available locally at Documents.
Where guidelines or information overlap, information in the California Supplement supersedes that of the FHWA MUTCD.
The http://www.dot.ca.gov/hq/traffops/signtech/mutcdsupp site is interesting in itself with access to training, policy, sign, and traffic manual information as well as links to the California Vehicle Code and the Traffic Control Devices branch.
Caltrans Standard Plans
The Caltrans Office Engineer web pages contain extensive information about Caltrans operations.
These pages from the Division of Engineering Services site at http://www.dot.ca.gov/hq/esc/ are well worth visiting. You might especially take a look at the Office Engineer pages at http://www.dot.ca.gov/hq/esc/oe/.
Maintenance Manual Volume 1, July 2006
The Caltrans Maintenance Manual presents general practice and procedures for maintaining the State highway system. The Maintenance Manual consists of two volumes. Volume 1 describes the Caltrans Maintenance Program and the methods and procedures it uses. Volume 2 describes the Caltrans Integrated Maintenance Management System (IMMS) used to record, report and monitor maintenance work planned and performed.
The Caltrans Maintenance Manual Volume 1 is available at http://www.dot.ca.gov/hq/maint/manual/maintman.htm. It is also available locally at Documents.
The long-awaited Volume 2 is currently not available. If you have an old copy, guard it well!
The Caltrans Construction Manual describes the Construction organization, practices, and procedures. It is available online at http://www.dot.ca.gov/hq/construc/manual2001/. The version available locally at Documents was last revised December 2006.