Product information 74923: The railroad grade crossing comes with half gates. This grade crossing can be connected directly to C Track. 2 solenoid activated gates with 2 red warning lights, which come on when the gates come down. This grade crossing is ready to be connected to the layout, easy installation. Contact track set: 3 straight tracks each 94.2 mm / 3-3/4". Dimensions for each base half 137 x 95 mm / 5-3/8" x 3-3/4".Product information 74930: This add-on set is for the 74923 railroad grade crossings for C Track. It is required for each additional parallel track. Contact track set: 3 straight tracks each 94.2 mm / 3-3/4". No other connections required. The road section can be adjusted for a spacing of 26 to 61 mm / 1" to 2-3/8" (track spacing of 66 to 101 mm / 2-5/8" to 4".