Corridor-trench with 90° bend

[eggerts11]

Is it possible to create a trench, using the corridor feature, which has 90° corners on each side?

I've tried using 3D polylines and setting them as targets for the corridor width and I've also tried adjusting the Frequency but so far I've not been able to achieve acceptable results. 

I‘ve attached pictures of the corridor. The inner corner looks almost right except for the boundary line (yellow) which crosses and falls to zero elevation. The green lines are the 3D polylines set as targets.  

[tcorey · Accepted solution]

You'll have better luck if you put a very small radius curve at the 90 degree bend in the baseline alignment.