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Evaluation of Bridge Approach Rails

Author : Roger P. Bligh

Publisher :

Page : 200 pages

File Size : 50,35 MB

Release : 1992

Category : Bridge railings

ISBN :

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Book Description

A recent study on the performance of guardrail-to-bridge rail transitions revealed that many widely used designs do not meet current safety standards. As a result, the Federal Highway Administration (FHWA) requested that the Arizona Department of Transportation verify the safety performance of its standard transition designs. Three transition designs currently being used by ADOT were evaluated through a combined program of computer simulation and full-scale crash testing. The standard ADOT wood post transition, incorporating a channel rubrail and two different sizes of timber posts at a reduced post spacing near the bridge rail end, was found to be in compliance with National Cooperative Highway Research Program (NCHRP) Report 230 performance criteria. The standard ADOT steel post transition with channel rubrail was also found to be in compliance with NCHRP Report 230 requirements when impacted near the end of the bridge rail. However, the upstream end of the steel post transition required modification to eliminate deficiencies identified during testing. The modified design, which terminated the channel rubrail behind a W6x9 guardrail post, was successfully crash tested. A recent study on the performance of guardrail-to-bridge rail transitions revealed that many widely used designs do not meet current safety standards. As a result, the Federal Highway Administration (FHWA) requested that the Arizona Department of Transportation verify the safety performance of its standard transition designs. Three transition designs currently being used by ADOT were evaluated through a combined program of computer simulation and full-scale crash testing. The standard ADOT wood post transition, incorporating a channel rubrail and two different sizes of timber posts at a reduced post spacing near the bridge rail end, was found to be in compliance with National Cooperative Highway Research Program (NCHRP) Report 230 performance criteria. The standard ADOT steel post transition with channel rubrail was also found to be in compliance with NCHRP Report 230 requirements when impacted near the end of the bridge rail. However, the upstream end of the steel post transition required modification to eliminate deficiencies identified during testing. The modified design, which terminated the channel rubrail behind a W6x9 guardrail post, was successfully crash tested.



Evaluation of Guardrail to Concrete Bridge Rail Transitions

Author : Roger P. Bligh

Publisher :

Page : 76 pages

File Size : 21,73 MB

Release : 2003

Category : Bridge railings

ISBN :

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Book Description

In December 2001, the Design Division and Bridge Division of Texas Department of Transportation released a new standard for an approach guardfence to concrete bridge rail transition that complies with the testing requirements of National Cooperative Highway Research Program (NCHRP) Report 350 for use on high-speed roadways. The purpose of this research was to develop a transition that is suitable for use on lower speed roadways and that is less expensive and complex than the current high-speed design. A low-cost transition was successfully evaluated at 45 mph impact speeds under NCHRP Report 350 Test Level 2 conditions. A second objective of the project was to evaluate the need for the curb detail that is one of the design elements of the newly adopted thrie beam transition design. Elimination of the curb would greatly enhance installation flexibility and reduce installation cost. The assessment of the curb was accomplished through full-scale crash testing.











Analysis and Design of Railway Bridges

Author : Mohiuddin Ali Khan

Publisher : Butterworth-Heinemann

Page : 250 pages

File Size : 17,82 MB

Release : 2017-08-04

Category : Technology & Engineering

ISBN : 0128044756

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Book Description

Analysis and Design of Railway Bridges brings together the analytical tools and design methods necessary to accurately interpret the complex design requirements in the selection process and construction of robust railway bridges. When designing railway bridges, design engineers must face a number of unique structural challenges such as: dead load of the structure, live loads from the carried, frequency of traffic, and dynamic components of the traffic such as impact, centrifugal, lateral, and longitudinal forces. This means the use of complex modeling tools for the selection of proper design criteria. This reference provides a clear and rigorous exposition of the various codes which govern design including: American Association of State Highway and Transportation Officials, American Railroad Engineering and Maintenance-of-Way Association, Federal Highway Administration and the Eurocode for dynamic factor, dynamic loading and load combinations, bridge parameters, modelling of excitation and dynamic behaviour, and verification for fatigue. Explains codes including: American Association of State Highway and Transportation Officials, American Railroad Engineering and Maintenance-of-Way Association, Federal Highway Administration, and the Eurocode Addresses the unique aspects of railway bridge modeling such as: bridge and train modeling techniques, substructure details, structural steel details, prestressed concrete details, and bridge railing and approach rail details Includes design and analysis methods and calculations as well as applications and solved examples Provides the analytical tools and design methods necessary to interpret complex design requirements



Testing and Evaluation of the Florida Jersey Safety Shaped Bridge Rail

Author :

Publisher :

Page : 102 pages

File Size : 22,88 MB

Release : 2004

Category : Bridge railings

ISBN :

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Book Description

The objectives of this portion of the project were to: 1) determine if any or all of the three subject variants of the 32-inch (813 mm) Jersey safety shaped bridge railing comply with the requirements of the AASHTO LRFD Bridge Design Specifications and National Cooperative Highway Research Program (NCHRP) Report 350 Test Level 4 (TL4), and 2) provide recommended retrofit schemes, if deemed technically and economically feasible, to bring into compliance the railings that do not comply. Full or partial replacement schemes may also be recommended as appropriate. The most direct approach for accomplishing the objectives of this task was to perform a full-scale crash test of the most critical design. If that railing performed satisfactorily, the railing would be acceptable by AASHTO LRFD Specifications. The strength test was selected, NCHRP Report 350 test 4-12, a single-unit van-type truck weighing 17,6211b (8000 kg). The TL-4 vehicle is a single-unit box-van truck impacting the railing at 15 degrees and 49.7 mi/h (80 kmIh). While containment is required, overturning of the vehicle is an acceptable test outcome. However, Test Level 3 (TL-3) is a 4405-lb (2000 kg) pickup impacting the railing at 25 degrees and 62.2 mi/h (l00 kmIh). This test requires both containment and stability, and non-overturning. Since some breakage of the parapet is possible, potential for vehicle snagging is likely. Vehicle snagging can contribute to vehicle instabilities in the redirection sequence and potential rollover. Therefore, researchers chose both TL-4 and TL-3 tests. According to the results of this project, no field retrofits or replacements of the Florida Jersey safety shaped bridge rails, depicted in the Florida DOT Index 799, are warranted since the most critical 32-inch (813 mm) Jersey safety shaped bridge railing complied with the requirements of the AASHTO LRFD Bridge Design Specifications and NCHRP Report 350 Test Levels 3 and 4.