Soil issues and/or poor construction are often the culprits for retaining walls that are tilting. This can happen if the footing toe is too small or if the wall wasn’t properly reinforced. Railroad tie retaining walls can begin to collapse due to wood rot or deterioration.
Most retaining walls require drainage “weeps”. If water accumulates behind the wall, this additional weight can cause clay soils to expand, leading to cracks and tilting.