INDIANAPOLIS — There’s plenty of debate over which American city has the heaviest traffic, with New York, Chicago, Los Angeles, Atlanta, Miami, Seattle, and Nashville all in the conversation.
When it comes to the IMSA WeatherTech SportsCar Championship, two events feature heavier traffic in terms of cars per mile of track than all the rest.
And they just happen to be the last two races of the season: the TireRack.com Battle on the Bricks at the Indianapolis Motor Speedway road course, and Motul Petit Le Mans at Michelin Raceway Road Atlanta.
They’re nearly identical in length – Indianapolis measures 2.439 miles, while Michelin Raceway is a tick longer at 2.54 miles. But two racetracks really couldn’t be more different; Michelin Raceway’s 12 corners wind their way up and down through hilly forests, while Indy is nearly completely flat, run within a stadium, characterized by two long straights.
Why is the traffic heavier? While IMS and Michelin Raceway are among the shortest tracks on the IMSA calendar, they feature uniquely larger fields. Indianapolis is the only sprint race on the IMSA schedule that includes all four WeatherTech Championship classes – Grand Touring Prototype (GTP), Le Mans Prototype 2 (LMP2), Grand Touring Daytona Pro (GTD PRO), and Grand Touring Daytona (GTD), creating a 44-car entry.
Michelin Raceway, meanwhile, marks the last of five rounds of the IMSA Michelin Endurance Cup. This year’s Motul Petit Le Mans race may draw up to 54 cars, but the track is considerably shorter than any of the other four IMSA Michelin Endurance Cup venues, which measure from 3.4 to 4.048 miles.
It works out to a very busy 18 cars per mile of track at Indianapolis, and an even denser 21 cars per mile at Michelin Raceway. For comparison, the Indianapolis 500’s 33-car field on IMS’ 2.5-mile oval works out to an average of 13 cars per mile.
But imagine that many cars packed onto a mile of a nearby Interstate highway, either I-65 in Indy or I-85 in Braselton, Georgia! Clearly, managing that traffic is a key element to success at either circuit, especially for drivers of the faster prototypes.
Earl Bamber, whose co-driving of the No. 31 Cadillac Whelen Cadillac V-Series.R has helped propel Jack Aitken to the top of the GTP points standings, revealed that creating a more predictable car in traffic was a key element in the design brief for the ‘EVO’ upgrades integrated into the V-Series.R this year.
“When we were doing the EVO, we were really targeting the raceability aspect and that was definitely achieved through being able to follow in traffic,” Bamber said. “With the EVO, we’ve got what we need on the straight – a bit less drag – and we’re able to follow close in the corners, which has just allowed us more opportunity to overtake in races at the right moments. It’s also helped us with GT traffic, and that was sort of the main component.”
Nick Yelloly and Renger van der Zande stand third in the GTP standings in the No. 93 Acura Meyer Shank Racing w/Curb Agajanian Acura ARX-06, 185 points behind Aitken. The Englishman believes his ability to maneuver through slower traffic is influenced by a combination of aerodynamics and mechanical grip.
“We usually tend to rely on the aerodynamic performance of the car, so we have to take quite a different philosophy into [Indianapolis] in order for us to be more competitive compared to a track like the previous race at Road America (where the No. 93 Acura finished fourth),” said Yelloly.
“You also have to really think about having good, combined traction, in my opinion, to be able to get by the slower traffic. Because if you struggle there, getting through in between the traffic in the tight spots is a bit tricky. And now it’s going to be a much shorter race compared to the years previous (six hours in 2024 and ’25), so making sure you have the car set up to be able to be aggressive in traffic is paramount.”
LMP2 drivers have twice as many traffic headaches, because they are trying to weave through slower GT class entries while at the same time keeping an eye on the mirror for incoming faster GTP machines. But most of those LMP2 drivers enjoy the double challenge.
“Indianapolis is a fun track in traffic,” observed Mikkel Jensen, who shares the No. 2 United Autosports USA ORECA LMP2 07 with Phil Fayer and has won at Indy each of the last three years with TDS Racing, prior to joining United.
“It’s a track that doesn’t really have super high-speed corners, so you don’t need to commit like you do on other tracks. But in another way, you really have to work with the car and the way the tires work. The traffic makes it very demanding through Turns 7-8-9, which are super tight. The GT cars don’t like to let you through, and you need to find your room. There’s a lot of action there every year, and the multi-class racing at this track, I think, is fantastic.”
Ben Barker confirmed that the close confines at Indianapolis can produce plenty of bumping and banging.
“It’s tricky,” said the Brit, who splits seat time in the GTD PRO class No. 64 Ford Racing Ford Mustang GT3 with Dennis Olsen. “I did the race two years ago in a GTD Mustang, and I think I probably got hit about 10 times by prototypes. Definitely a bit of door bashing going on. It’s quite slow speed, so I think the speeds are kind of matched between GT and prototype cars in quite a lot of places.
Although there are two fairly long straights, it can get tight, and patience is a virtue, especially for the prototypes through that sort of middle section, the esses.”
GTD PRO features the tightest title battle among the four WeatherTech Championship classes, with the top five contestants clustered within 67 points – the closest fight with two races to go in the class’ history.
Neil Verhagen and Connor De Phillippi top the standings in the No. 1 Paul Miller Racing BMW M4 GT3 EVO and hope to make all the right moves in traffic throughout the next two races to clinch the crown.
“For me personally, I think (Michelin Raceway) Road Atlanta is the most difficult to manage in terms of traffic, because Indy offers two long straights,” Verhagen said. “It’s difficult for the prototypes, but it’s equally as difficult for us, because we always have to really be watching not only what’s ahead of us, but also what’s coming from behind us, too.
“At the end of the day, I guess you just trust the spotters and hope they make the right calls,” he added. “And a bit of luck comes into it as well too, where you catch a driver at which point of the track.”
