When roads curve, something interesting happens to make sure your car stays safe. This clever trick is called superelevation, cant, or banking. In simple terms, it’s the tilt given to the road surface at a curved section to prevent your vehicle from tipping over or skidding.
Imagine you’re driving on a winding road. As you turn, your car wants to fling itself outward due to a force called centrifugal force. Superelevation steps in to counteract this force, keeping you on the road and avoiding any unwanted drama.
We often describe superelevation using a ratio – the height difference between the outer and inner edges of the road divided by the road’s width. This ratio, represented by ‘e’ or S.E., tells us how much the road slopes. Think of it as a gentle tilt that keeps you safe on curves.
Let’s break it down:
Counteracting Centrifugal Force: It stops your car from feeling the need to fly off the road when turning.
Safe Curved Driving: It lets you zip around curves without worrying about tipping over or skidding.
Traffic Safety: For everyone’s safety, especially on fast-paced roads.
Road Wear and Tear: Proper superelevation ensures the road doesn’t get beat up due to uneven weight distribution from passing vehicles.
Now, let’s explore why superelevation is a road superhero:
Smooth Curved Driving : You can take curves at high speeds without fear, boosting traffic flow.
Even Load Distribution : It spreads the weight on your wheels evenly, reducing wear and tear on your vehicle and saving money on road maintenance.
Traffic Harmony : Keeps vehicles in their lanes, avoiding collisions on curved roads.
Drainage Magic : Helps water flow towards the inner side, eliminating the need for drains on the outer side.
Designing for Mixed Traffic : Creating the perfect superelevation for a mix of vehicles is a bit like solving a puzzle. Here’s how we do it:
Step 1: Calculate superelevation for 75% of the design speed, ignoring friction.
Step 2: If the calculated value is less than 7%, use it. If not, stick to the limit and move on.
Step 3: Check friction coefficients. If it’s less than 0.15, you’re good. If not, it’s time for some speed restrictions.
Step 4: If friction exceeds 0.15, restrict the vehicle’s speed. For important highways, it might even be worth redesigning the curve for a smoother ride.
