What is described as an overcrossing in transportation infrastructure?

• A. A structure carrying a river under a highway
• B. A bridge spanning a railway
• C. A structure carrying a county road over a state highway
• D. A tunnel beneath a city street

Answer: (C)

An overcrossing in transportation infrastructure refers to a structure that allows one roadway to pass over another at the same or different elevation. This is commonly designed to facilitate traffic flow without intersecting paths, which can enhance safety and reduce congestion.

The correct answer describes a structure that carries a county road over a state highway, which fits the definition of an overcrossing perfectly. In this scenario, the county road is elevated relative to the state highway below, allowing vehicles on the county road to traverse the highway without any interruption to the highway traffic.

The other options do not properly describe an overcrossing. For instance, a structure carrying a river under a highway, while it does involve an elevation difference, is not categorized as an overcrossing since it pertains to a water body rather than a roadway. A bridge spanning a railway also does not classify as an overcrossing of a road over another road, but rather as a crossing over a different type of transportation infrastructure. Lastly, a tunnel beneath a city street focuses on going under a roadway rather than spanning over it, which contrasts with the concept of an overcrossing where one structure is elevated above another. Thus, the option that correctly identifies an overcrossing is the one describing the county road