Section 3: Overview of Texas Policy on Bridge Railing
Anchor: #i1000708Overview
Bridge railing is required for all bridges except bridge-class culverts. Design speeds of 50 mph and greater require a rail rated at least TL-3. Design speeds of 45 mph and less require a rail rated at least TL-2.
New bridges. Texas bridge railing on new construction must meet FHWA crash-test criteria as specified in NCHRP Report 350.
Existing bridges scheduled for rehabilitation. TxDOT evaluates bridge railing for conformance to current standards whenever any improvements are made to any bridge or its approach roadway. In general, an existing obsolete railing within a safety improvement project must be brought up to current standards, or else the project must obtain a design exception, providing that railing replacement is scheduled within a reasonable time. However, if bridge railing complies with requirements predating NCHRP Report 350 (expressed in NCHRP Report 230), is already in place in a non-freeway rehabilitation (3R) project, and is not scheduled to be upgraded by the project, upgrade may not be required.
Bridge Division staff are available to advise districts on requirements and on options.
Existing bridges not scheduled for rehabilitation. Obsolete railing need not be brought up to current standards on a bridge that is not being rehabilitated.
Anchor: #i1000739Approval of Bridge Railing
A bridge railing type can be approved for use on Texas bridges in any one of the following ways:
- It has been successfully crash tested in accordance with NCHRP Report 350 criteria.
- It has been approved for specific uses by FHWA after evaluation of results from successful crash testing based on criteria that predate NCHRP Report 350.
- It has been evaluated by TxDOT and identified as similar in strength and geometry to another rail that has been successfully crash tested in accordance with NCHRP Report 350 criteria.
Bridge Railing Transitions
Bridge railing on any Texas bridge must connect with roadside guard railing if it is present. TxDOT provides railing transition details in Design Division Standards and transition connection details in Bridge Division Standards. The transition selected must be appropriate for the design speed. Design speeds of 50 mph or greater require a TL-3 transition. Design speeds of 45 mph or less can use a TL-2 or TL-3 transition.
Anchor: #i1000787Railing on Culverts
Protect the ends of bridge-class pipe and box culverts by providing, in order of preference, safety end treatments, metal beam guard fence, or bridge railing as described in the Drainage Facility Placement section of the Roadway Design Manual regardless of horizontal clearance (clear zone). Bridge railing is frequently not an option with bridge-class pipe culverts. A pedestrian-only railing used alone is not acceptable for bridge-class culverts; traffic railing or combination railing must protect pedestrians and pedestrian-only railing from vehicular traffic on bridge-class culverts. Alternatively, a safety-end treatment can be used with a pedestrian-only railing.
Railing on bridge-class culverts must conform to the same requirements as bridge railing, with the following exceptions:
- Metal beam guard fence meets TL-3 requirements and is an option only if 44 inches of fill is present and posts are embedded as required on the Metal Beam Guard Fence standard drawing. Bolting posts to a bridge-class culvert is not allowed.
- Bridge railings must be properly anchored using the details shown on the Rail Anchorage Curb standard drawing and the details shown on the standard drawing for the selected bridge railing type. Another standard drawing, T6-CM, provides details for anchoring a Type T6 rail to culverts.
For existing box culverts where bridge rail is required, anchor the railing properly using the details shown on the standard drawing for the selected bridge railing type and the details shown on the Rail Anchorage Curb Retrofit guide drawing, which applies for fill heights of 2 ft. or less. If the Rail Anchorage Curb Retrofit guide drawing does not apply, the Bridge Division is available to provide project specific details for the addition of bridge railing.