Question 1

What is a parabolic transition ramp?

Accepted Answer

A parabolic transition ramp is a curved section where the road grade changes gradually rather than instantly. Instead of a sharp corner between a flat floor and a sloping ramp, the grade increases linearly along the curve length, which prevents low vehicles from grounding their underbody at the grade break.

Question 2

How do you calculate the transition length for a ramp?

Accepted Answer

The common mid-belly formula uses R = WB squared divided by 8 times the ground clearance, then transition length equals R multiplied by the gradient. However this only protects the wheelbase midpoint. Vehicles with long front or rear overhangs often need a much longer transition, so the governing point should be verified by simulating the full vehicle body.

Question 3

What is breakover angle?

Accepted Answer

Breakover angle is the maximum ramp peak angle a vehicle can cross without the underbody between the axles touching the ground. It is calculated as twice the arctangent of two times the ground clearance divided by the wheelbase.

Question 4

What gradient should a car park ramp be?

Accepted Answer

Typical car park ramps range from 1:10 to 1:6 depending on local code. Steeper gradients require longer transition curves at both the bottom sag and top crest to prevent low vehicles from scraping. Always verify the specific vehicles expected to use the ramp.