Why key corners of Miami's F1 track are "on the limits of design"

UK specialists Apex Circuit Design laid out the 5.41-kilometre anticlockwise circuit, which hosts its first Formula 1 Grand Prix next weekend, around the Hard Rock Stadium in Miami Gardens.

Its most sinuous section is through Turns 13-16, which wind around the entrance and exit ramps and beneath the flyover sections of the Florida Turnpike, the main toll road between Miami and Orlando, and NW 203rd Street.

The track is expected to produce an average lap speed of just under 135mph, and this slow-speed section precedes a 1.28km, 320kph straight that leads towards the hairpin at Turn 17.

The approach to Turn 17 should be the track’s key overtaking opportunity and the compression effect of the Turn 13-16 sequence should ensure close running onto the back straight.

The FIA regulations regarding clearance of overhead structures to the track surface means the layout needs to dip beneath the two overpasses, shortly after rising 11 feet to cross the Southbound access ramp, creating a crest in the Turn 14-15 chicane that will severely punish any driving errors.

Miami track Turn 15 during build process

Photo by: Charles Bradley

“This whole sequence was a real engineering challenge,” said Apex project lead design engineer Andrew Wallis. “[Apex founder and director] Clive Bowen’s concept design required us to route the track through this zone and for us to get beneath the first overpass, we had to meet the FIA regulation that requires at least four metres of clearance, but as we have to tie into the levels of the Turnpike slip road that has a 7% crossfall, our track surface was climbing just at the point where we needed it to be falling.

“There is also an F1 regulation about the rate of change of elevation linked to the square of the speed of the car, so this design basically threads the needle in three dimensions to ensure that the cars go slowly enough to align with the camber of the crossing and then get back under the overpass.

“We’ve created this pretty dramatic corner sequence where you have a sharp chicane, which has a minimum design speed of 80kph to meet the rate of change regulation, and it’s also completely blind for the drivers because of the elevation change. We simulated over 10 design iterations here to achieve the 2D and 3D geometry required to thread the needle.

“We’re right on the limitations of design in this area. In this location, we’re having to install the debris fence from behind the barrier because there is no room to lift the debris fence over the barrier.”

This whole section of track follows a tight left-hander at Turn 11 that exits into a flowing right-hander through Turn 12, which is off-camber, and should create a challenge in itself as the cars will be highly loaded on the approach.

“I think the T11-T16 sequence features some great corners and hopefully the drivers will find it challenging with the new cars,” added Wallis. “They will have to prepare while they’re coming through the previous right-hander, so not only can you not see the apex you’ll have a lateral load on the car under braking, while spotting the apex late to make the corner. In qualifying, I think it’ll be a truly make-or-break corner for the overall lap time.

“Arguably this is the most technically challenging part of the track. It then leads on to the longest straight, so any potential mistakes could be cumulated by the time drivers reach Turn 17 and should promote overtaking opportunities and, if nothing else, will bunch cars onto the straight.”

The Turnpike freeway is less than 25 metres away from the track at this point, and this area will be inaccessible to the public with only marshals stationed there.

Apex’s project director Sam Worthy added: “Having the Turnpike so close, to protect the race cars and the marshals we will erect barriers and screens along the boundary so that drivers on the Turnpike aren’t distracted by what’s going on. So that was a major concern to us, to ensure it’s a safe race for everyone.

“As there’s no room to have any grandstands or spectators here, F1 has been very keen to fill this area with cameras to ensure multiple TV viewing angles – as we know we’ll see a lot of interesting on-track action here.”