Topeltkihid

Topeltkihid is an Estonian term used in civil engineering to describe a bridge configuration in which two parallel decks span the same substructure. The arrangement is typically employed to separate traffic streams, increase capacity, or provide redundancy. The decks may carry different functions, for example one for road traffic and one for rail, or may both serve road traffic with different directions or speeds. Designers must address interaction between decks, including load distribution, dynamic effects, and differential settlement, and may use independent or communicating diaphragms and framing.

Construction approaches vary. In some projects, the decks are built sequentially on a common substructure; in others, the decks are constructed together as a modular, sandwich-like system. Variants include stacked decks (one deck directly above the other) and parallel decks sharing piers or abutments. Benefits include higher capacity, more versatile traffic management, and improved resilience against partial deck failures. Drawbacks include higher material and foundation costs, increased construction complexity, and maintenance access challenges.

Topeltkihid are used in urban river crossings, rail corridors integrated with highways, and other environments where space is constrained and high capacity is required. They relate to broader concepts such as double-deck bridges and sandwich-structured bridges within the field of structural engineering, reflecting continued interest in maximizing efficiency and redundancy in bridge design.