Traditional road horizontal alignment design faces bottlenecks such as limited terrain representation, inefficient information updates, and inadequate multi-factor collaboration. Underground pipeline design also encounters issues of professional fragmentation and frequent conflicts. The lack of coordination between the two leads to construction rework and increased costs. Based on this, this paper first constructs a BIM-based technical system for road horizontal alignment and then explores collaborative avoidance techniques for underground pipelines. Using engineering examples, it investigates the BIM-integrated application of collaborative avoidance between road horizontal alignment and underground pipelines. Through analysis, the paper aims to address the challenges of coordination in road and underground pipeline design, break down professional information barriers, proactively avoid conflicts, and provide technical support and practical references for enhancing the quality and efficiency of municipal engineering design.