What is the difference between a bridge and a trestle? Bridges and trestles are both essential components of transportation infrastructure, serving as vital links in roadways, railways, and pedestrian paths. The difference between a "bridge" and a "trestle" lies primarily in their design, structure, and function:

　　1. Definition

　　- Bridge: A bridge is an elevated structure that spans across a physical obstacle to connect two areas. It can be made from various materials such as concrete, steel, wood, or stone and comes in different forms including beam, arch, suspension, truss, and cantilever.

　　- Trestle: A trestle, often seen in railway contexts, consists of multiple rows of supports connected by crossbeams to form a framework that elevates the track above ground level. It’s essentially a series of triangular frames that support the deck on which trains run.

　　2. Structure and Design

　　- Bridge: Simplest type with beams supported at either end, Typically features a framework of timber, steel, or concrete piers that support the deck. The design is modular, with repeated sections.

　　- trestles : Typically consists of a deck (the surface people or vehicles travel on) supported by piers, abutments, or arches.Uses arches to distribute weight to the ground through abutments.

　　- Trestles, on the other hand, are characterized by their repetitive and regular pattern of supports, making them well-suited for long, straight stretches where ground conditions require elevation. They provide a stable base for railway tracks but are less common in modern highway constructions due to space constraints and aesthetic considerations.

　　3. Usage and Functionality

　　- Bridges are used in various settings to span gaps where direct land connection isn’t feasible or desirable (e.g., rivers, highways, city streets). Their versatility makes them crucial in urban planning and critical for facilitating traffic flow over natural barriers.

　　- Trestles specifically serve railway needs, especially when routes need to cross uneven terrain, ravines, or marshy lands unsuitable for traditional embankments. They offer cost-effective solutions in remote locations where building costs would otherwise skyrocket due to ground instability or steep gradients.

　　Key Difference

　　- A bridge is a broad term for any structure that provides a passage over an obstacle.

　　- A trestle refers specifically to a framework-style support system, often part of a bridge, but not always. Trestles are typically used for lighter loads and shorter spans.