Yesterday’s reduced practice time and installation of a chicane for the Baltimore Grand Prix prompted the ALMS to announce before qualifying that it would set the starting grid for today’s race in class order: P1, P2, PC, GT and GTC.

With the Prototype cars all running close to the same speeds and the GT cars nearly equal, working traffic will be especially challenging today for the GT cars. Here is why:

Christophe Bouchut’s P2 class pole was just 1.9 seconds off the race pole time of 1:25.174 set by Lucas Luhr aboard the Muscle Milk Honda. Bruno Junquiera PC pole for RSR was just another 0.3 seconds back.

P2 and PC class rules require a combination of a Pro and Sportsman level co-drivers. Typically, the pros qualify the cars and the sportsmen, some of whom are actually quite good, start the race. Since they are not quite as quick as their co-drivers are, the times are nearly equal to the GT cars, but the cars achieve their lap times in different ways on the 2.04-mile circuit.

The GT class is perhaps the most fiercely contested battle in international racing today with top teams and drivers for Corvette, BMW, Porsche, Ferrari, Lotus, and SRT Viper. .

The challenge for the GT leaders will be to get around any of the slower PC cars as quickly and cleanly as possible. As the two-hour race progresses, traffic will quickly jumble the classes. GT drivers will constantly need to find places and means to get through the slower GTC cars and around any stray PC cars without being collected themselves by the leading P1 and P2 cars.

Concrete walls, a bumpy track and limited grip off the main racing line provide significant disincentives to move over or make passes off-line. And competitors in all five ALMS classes are very aware that the ALMS Championships are on the line with just two races remaining after today.