What determines the placement of weep holes in structures?

The placement of weep holes in structures is primarily determined by water pressure behind abutments. Weep holes serve as drainage points that allow water to escape from behind a retaining wall or abutment, thus relieving hydrostatic pressure that can accumulate due to groundwater or rainwater. When water builds up, it can lead to increased pressure that may compromise the structural integrity of the bridge.

By strategically placing weep holes, engineers can effectively manage water accumulation and mitigate the risk of water-related damage, such as erosion or settlement. The design must consider the specific conditions and hydrology of the site to ensure that the weep holes are effective in preventing excessive water build-up.

The other options, while they may be relevant factors in overall bridge management or design, do not directly influence the technical rationale behind weep hole placement. For instance, maintenance check frequency relates more to the upkeep schedule rather than the water management design. The location of construction materials would factor into the overall design and structural considerations but not specifically into weep hole placement. Lastly, the type of traffic using the bridge can affect load considerations but does not dictate drainage strategies like weep hole placement does.