Getting the point of intersection between a feature line and a corridor with entity.IntersectWith. c# .NET

[cross1PXVS4]

Is it possible to get the point of intersection (circled in the picture) between a feature line and a corridor? 

The feature lines are relative to the corridor surface and I want to create a plugin that will get the point of intersection and then grade the feature lines outward at their respective slope (For lot grading).

However, the entity.IntersectWith method tells me the feature lines do not intersect with the corridor.

[cross1PXVS4]

Is it possible to get the point of intersection (circled in the picture) between a feature line and a corridor? 

The feature lines are relative to the corridor surface and I want to create a plugin that will get the point of intersection and then grade the feature lines outward at their respective slope (For lot grading).

However, the entity.IntersectWith method tells me the feature lines do not intersect with the corridor.

[hosneyalaa]

@cross1PXVS4 

you need External borders OF corridor

To implement The intersection

[hosneyalaa]

@cross1PXVS4 

you need External borders OF corridor

To implement The intersection