Should I resign from my internship from Hell?

I currently work at a large government agency in the mid west.

I have been working here for five months now.

At the beginning of June, I was placed in charge of an $8 million road resurfacing project.

I thought I was making good progress and was going to get the project done on time (plans are due at the end of July), but it turns out I drew my typical sections wrong and I need to calculate saw cut, dowel bar, and welded wire reinforcement quantities for almost 200 patches. I do not know how to perform these calcualtions and no one is available to show me as this place is understaffed to the bone. This is my first project I have ever worked on.

I don't think God himself could've met this project deadline, let alone a clueless intern who's only been employed in civil engineering for five months.

These calculations seem insanely complicated and confusing.

I feel that I will never succeed in this field (because mentoring has become a thing of the past) nor will I ever become a competent engineer.

Should I resign and possibly consider a career change?