Troubleshooting nat gas pipe questions

Hey all, I've been lurking here for awhile sucking up knowledge but now have a question.

Little background I've been doing this work for 2 years now and have learned alot, the previous guys at my station in charge of cathodic protection were not super knowledgeable and have been forced to mostly sink or swim between normal training so I don't have much in the way of people to try to bounce questions off of.

I've been troubleshooting a section of wrapped steel approximately 425' long that a railroad crosses in the middle no casing. There 1 test station on North and south side and the reads have been abysmal -.20v range. We performed a current drain taking off from the North's test station, taking on(4 sec) off(1 sec) reads with wire reel taking extended half cell reads over the pipe all was going good then as we got over the railroad section the reads stoped shifting correctly and switched to being less negative during the on cycle and more negative during the off cycle. As we continued to move towards the south side the reading switched back once we left the railroad section. The test point on the south side was also shift correctly. This is the first time I have seen this happen with a current drain other than taking reads on the off side of the pipe at insulator and such. What would cause this to happen in a plaection of pipe that is connected? Through other testing we are pretty positive our issues is at the tracks at this point but this really has me scratching my head. Any insight would be very much appreciated.

Fyi sorry for wall of text this was types on my phone.

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