Complex sentence: At Longview Junction, which is east of Longview, I-5 intersects SR 432 and continues north to Kelso, where I-5 intersects SR 4, which formerly was US 830, and SR 431 before starting curving northeast towards Castle Rock.
Split into simpler sentences: At Longview Junction, east of Longview, I-5 intersects SR 432 and continues north to Kelso. Here it intersects SR 4, formerly US 830, and SR 431 before curving northeast towards Castle Rock.