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Section 8: Rail Damage Due to Vehicular Impact

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Description

Traffic rails frequently sustain damage from vehicular impact, often resulting in reduced structural capacity. It is imperative to implement repairs to railing that restore capacity, in the event that the same section of rail is impacted again.

Many rail types include steel components mounted to concrete parapets. Although this manual addresses concrete repairs, damage to steel elements must also be considered when rail damage is assessed and repaired.

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Assessment

Damage to railing can be categorized as minor, intermediate, or major. Damage should be assessed on a case-by-case basis.

Minor rail damage is defined as spalling or cracking that does not extend beyond the outer reinforcing steel cage, with no loss in structural capacity, and that covers an area of less than 12 square inches. Additionally, there is no deformation of any steel components.

Intermediate damage extends beyond the outer cage of reinforcement but based on the Engineer’s assessment hasn’t significantly reduced rail capacity. The maximum depth of an intermediate spall is 6 inches.

Major rail damage occurs from any impact that necessitates restoration of structural capacity. Damage is typically greater than 6 inches deep and results in plastic deformation of reinforcing steel, anchor bolts, or other steel elements.

The Engineer may evaluate slight deformations in steel elements or reinforcement to determine whether they can be reused.

Even slight deformations in galvanized steel can severely limit its long-term viability in preventing corrosion; therefore, damaged galvanized elements should typically be replaced rather than repaired or touched-up. In no case should damaged anchor bolts be reused.

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Repair Procedure

Minor rail damage: Repair spalls in accordance with Section 1 (epoxy mortar) or Section 2 (proprietary, bagged concrete repair materials) of Chapter 3 in this manual. Seal cracks in accordance with Section 6 (gravity-fed epoxy) or Section 7 (surface seal) of Chapter 3. Touch up any scrapes or other minor damage to steel elements in accordance with standard District maintenance practices. If any galvanized elements are impacted, then the Engineer should evaluate to determine appropriate repair procedures, such as touch-up using zinc-rich paint.

Intermediate rail damage: Repair spalls in accordance with Section 2 (proprietary, bagged concrete repair materials) or Section 3 (batched concrete) of Chapter 3. Ensure there is a mechanical bond by completely excavating around exposed reinforcing steel.

Major rail damage: When damage is severe enough to reduce the structural capacity of a rail, the best option for full restoration is to remove the rail to the level of the concrete deck and retrofit in accordance with the TxDOT Bridge Standards Retrofit Guide for concrete rails or curbed structures. All damaged components should be replaced or supplemented, and structural class batched concrete should be used to cast the new section of concrete railing.

If the Engineer determines that major rail damage can be repaired rather than retrofitted to sufficiently restore capacity, perform work in accordance with Standard Specification Item 778, “Concrete Rail Repair.” When feasible, utilize batched concrete rather than proprietary, bagged material to patch the damaged rail.

Installation of new anchors and reinforcement is critical to ensuring adequate capacity of the concrete railing and steel-mounted components. When using epoxy to anchor steel bars, install in accordance with Standard Specification Item 450, “Railing.”

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