Yes, the grade in that last turn is 7%, which is far beyond any recommendations for a riding railroad. And if any weeds get in between the wheels and the rails, it slips big time.
For those who might not be familiar with some of the intricacies, chickens are used to de-worm the roadbed before laying any track. When the transcontinental railroad was built, thousands of chickens were employed for this very purpose. You can look it up on Wikipedia. Yep.
The pull cart had traction issues pulling the flat car up the steepest grade because the wheels were crushing the green grass and lubricating the rails causing it to slip back down the grade. So I weedwhacked both sides of each rail so that nothing green touched, and it works much better...