No there is not any limit for a track lap distance (although the FIA recommends a maximum lap length of 7Km in its procedures for the approval of new F1 circuits), but, in any case, one single strait section can not exceed 2Km. However, race duration is timely capped. The race length is defined as the smallest number of complete laps that exceeds 305 Km, though occasionally some races are truncated due to special circumstances. In the 2012 undergoing season the circuit with the biggest lap distance is Spa-Francorchamps in Belgium with 7.004 Km (44 laps race) and the shortest track is the Monaco Grand Prix with 3.340 Km. This circuit is the unique exception to the minimum 305Km rule, since the race only lengths 78 laps for a total of 260.520 km. Each Grand Prix has a maximum of 2 hours (race ends in the final lap after 2 hours have passed) and can be extended to a total maximum duration of 4 hours (including race suspension time), which means that under certain special circumstances the 2 hours rule could be redundant. This last rule is a novelty introduced by FIA in 2012.