The correct answer is option 'D' (130 km/hr).

Explanation:

The wind load on a highway bridge is an important consideration in the design and construction of the bridge. Wind can exert significant forces on the structure, and these forces need to be taken into account to ensure the safety and stability of the bridge. The wind velocity at deck level is a key factor in determining the wind load on the bridge.

When the wind velocity at deck level exceeds a certain threshold, the live load on the bridge is not considered. This is because the wind load can have a greater impact on the bridge than the live load. The live load refers to the weight of vehicles and pedestrians on the bridge.

The threshold wind velocity at which the live load is not considered varies depending on the design codes and standards followed. In this case, the correct answer is option 'D' (130 km/hr), which means that when the wind velocity at deck level exceeds 130 km/hr, the bridge is not considered to be carrying any live load.

It is important to note that this threshold value is specified to ensure the safety and stability of the bridge under high wind conditions. When the wind velocity exceeds this threshold, the design of the bridge should be able to withstand the wind forces without relying on the contribution from the live load.

By not considering the live load during high wind conditions, the design can be simplified and the bridge can be made more robust to withstand the wind forces. This helps in ensuring the safety and longevity of the structure.

In conclusion, the correct answer is option 'D' (130 km/hr) as the wind velocity at deck level above this threshold is considered to be high enough to disregard the live load on the highway bridge for the purpose of design and analysis.

70km/hr