Michigan Tech Glossary Tech Alive
 Start Over Glossary Technical Support



friction factor, f

A coefficient that is a function of the design speed.  Obtained from the AASHTO Design guide.  Usually in the range 0f 0.1 to 0.3.

Return to Lesson



Grade is the rise or fall of the roadway profile per 100 units in length.  Usually expressed as a %

Return to Lesson


gravitational constant, g

g = 9.81 m/s2 or 32.2 ft/s2

Return to Lesson


Super elevation, e%

The cross slope to a road that is used to counteract the centripetal forces developed as a vehicle goes around a curve.  Maximum value is approximately 10%

Return to Lesson


Stopping Sight Distance

The distance required for a vehicle to observe, react and brake the vehicle to a stop. Calculated in two parts: the perception reaction distance and the braking distance Stopping Sight Distance Equation
Go to Spreadsheet

Return to Lesson


Velocity, V

Speed of the design vehicle  

Return to Lesson


Vertical Curve

A regular curve that has a quadratic mathematical form.  For vertical curves the general equation is

Vertical Curve Equation

A is the grade difference

L is the length of parabolic curve

X= distance from beginning of the curve to the point of interest

Return to Lesson