Northern Illinois Raceway is a four-configuration road course in DeKalb, Illinois.
NIR is famous for its five-turn Corkscrew sequence, as well as for its Spur layout, which features 8 hairpin turns. The NIR facility is also the flattest road course on the entire circuit, with only 18 feet of elevation change.
The Classic Course of Northern Illinois Raceway features 10 turns and its infamous Corkscrew (not to be confused with the more universally known Corkscrew of Mazda Raceway Laguna Seca).
The front straightaway is the second of four straights of similar length broken up by high-speed corners. Turn 1 is a sweeping 80-degree right-hand corner, leading to another straightaway. Turn 2 is a sharp 30-degree left-hander with a high curb, discouraging racers from trying to hop the corner.
Turns 3 and 4 form the Toe, a pair of 90-degree right-handers. Turn 4 is considerably sharper than Turn 3, although it doesn't look it on entry. The gravel trap on the outside of the corner is a popular place for overeager racers to find themselves.
Another long straightaway leads into the Corkscrew, a difficult five-turn sequence of alternating corners that increase in severity. The Turn 5 right-hander is known as The 15, due to its angle of 15 degrees. Turns 6 through 9 are known as The 45, The 90, The 120, and The 150.
Turn 9, or The 150, is the sharpest corner on the circuit and leads into the last straightaway before the sharp 30-degree right-hander of Turn 10 that brings cars back to the start-finish line.
NIR's 6-turn Spur section was constructed many years after the original 10-turn layout, due to popular demand. A fan contest was held to design an expansion for NIR in 2019, and the winning design was implemented in 2021.
The Spur is now used in both the Full Course and the Spur Course, although the second expansion that makes up the other half of the Spur Course was not constructed until 2029.
The Full Course runs from the start-finish line of the Classic Course until halfway down the final straight. It then takes a sharp 90-degree left-hander (Turn 10) onto the Spur.
Turn 11 is a sweeping 90-degree right-hander that leads into another quarter-mile straightaway. Then the fun begins with Turn 12, a 180-degree right-hand hairpin that immediately leads into a 180-degree left-hand hairpin in Turn 13. A short straight then leads into Turn 14, another 180-degree hairpin, and then yet another quarter-mile straight takes racers into the final corner--Turn 15--which is yet another 180-degree left-hand hairpin that heads straight back onto the frontstretch.
All told, the Spur section adds four hairpin corners, and yet all are slightly different in severity, degrees, and speed, giving racers a true challenge. In fact, the Spur was so popular that eight years later, an expansion for the Spur was constructed in the infield of the Classic Course to really give drivers a nightmare.
Spur Course and Short Course
That nightmare was the Spur Course. This expansion only adds three turns, but they're all carousels. In fact, the whole course is 10 turns long and 8 of them are hairpins or tight carousels.
Turn 1 of the Spur Course starts out with the entrance into Turn 1 of the Classic Course, but continues turning into a decreasing-radius carousel. The exit of this corner is a quarter-mile straight leading into Turn 2, a tight 200-degree left-hander that leads into the more wide 200-degree right-hander of Turn 3.
A slight correction to the left halfway down another quarter-mile straightaway leads cars into Turn 4, or Turn 9 of the Classic Course--The 150. From there, cars follow the route of the Full Course back to the start-finish line.
The 8 hairpins of the Spur Course are all different from each other, ranging from 150 degrees to over 200, with varying radii, leading into different-length straightaways. Between the Spur Course and the Classic Course, NIR is one of the most popular racetracks in the game for racers who like a challenge.
This infield expansion also allows for a fourth configuration, a short five-turn affair known as the Short Course, which follows the Spur Course through Turn 4, and then takes the Classic Course's 30-degree right-hander back onto the frontstretch.