Design speed

Design speed is like choosing how fast you want to drive a car before you even build the road or the car itself. It's like asking the question, "how fast do I want this road to be so that I can drive safely and efficiently?"

When engineers plan a road, they need to decide how fast cars should be able to travel on it. This decision is called the design speed. They consider the type of terrain, the number of curves or bends, the number of bridges or overpasses, and many other factors to determine the speed that a car can travel safely on the road.

The design speed is important because it affects many different aspects of the road's design. For example, if the design speed is higher, then the road needs to have wider lanes, fewer curves, longer sight lines, and better pavement quality, among other things. All of these factors help drivers to travel safely at high speeds.

Basically, design speed is like building a road with a speed limit in mind before anyone has even driven on it. It's an important decision that affects everything from the road's layout to how safe it is to drive on.