Bridge Expansion Joint for Bridges with Drainage Channels

Bridges with integrated drainage channels require expansion joints that are compatible with the drainage system. The joint must allow water to flow freely into the drainage channel while preventing water from infiltrating the bridge structure. Drainage channel continuity at the expansion joint requires a flexible connection that allows the drainage channel to move with the bridge deck while maintaining the drainage function. The flexible connection must be watertight to prevent water from escaping the drainage system at the joint location. Joint drainage design must ensure that water that infiltrates the joint is collected and directed to the drainage system. A drainage trough below the joint collects the water and directs it to the drainage outlets. The drainage trough must be sized for the maximum expected water flow, including the flow from the joint waterproofing failure. Waterproofing at the drainage channel joint must prevent water from infiltrating the bridge structure below the drainage channel. A flexible waterproofing membrane bridging the joint gap provides the primary waterproofing. The membrane must be bonded to the drainage channel on both sides of the joint and must be flexible enough to accommodate the movement. Maintenance access to the drainage channel joint requires removal of the joint cover or the drainage channel grating. The drainage trough must be cleaned regularly to prevent blockage. Any damage to the waterproofing membrane must be repaired promptly to prevent water infiltration. Corrosion protection of the drainage channel at the joint location must be enhanced because the joint area is subject to water and debris accumulation. Hot-dip galvanizing plus a two-coat epoxy system is the minimum requirement for the drainage channel at the joint location.