I cross rails all the time, and never have any issue when they are at 90. Just get light as you cross... its almost like you are shooting the bike forward under you to get over.

Howeverl there's one set at about 45 degrees, mid-way up a short but steepish hill.... i always get the front tire over without issue, but many, many time I have fishtailed badly as the back tire hits. Never fallen yet, but they scare me.

My most dangerous fall yet (although I wasn't hurt) happened when I tried to pass a slow moving truck. Mid way through the pass, rail tracks started in the middle of my lane, and I didn't notice till the last second. Again, I was able to get my front tire over, but I was travelling at at 30-35 kph, and fishtailed too hard. I could probably have gotten away if it wasn't for traffic (the car I was passing on the right, and an oncoming car on the left), but my number one concern was just staying in my lane. I did that, but went down fairly hard.
(Coming into Granville Island, Vancouver)