14" R curve minimum on the main loop. Atlas code 83 18"R Snap switches. Flex track is Peco code 83. Power is an Athearn SW1500 and all rolling stock is able to get around 13.25" R curves. Some cars can handle a 12" R curve, as can the engine while coupled. Just something fun I can move around and work on throughout the house. Next major step is cutting down the four switches and soldering them together and soldering some printed circuit board to the crossing area and constructing the crossing.