The Bahrain Grand Prix scheduled for April 22 is arguably the most difficult of all 20 races on the 2012 calendar to call, not just because it may yet be canned at short notice due to political unrest.The 2011 Bahrain race, scheduled as season opener, was first postponed, then cancelled completely, after it became clear civil strife in and around the capital Manama made the event untenable. As the opening trio of races proved, the key to the 2012 season is understanding the two compounds allocated per grand prix by sole tyre supplier Pirelli. Yet the rubber company has zero historic data to call on for an extremely demanding track surface under desert conditions. BATTLING THE ELEMENTSBuilt on a 170-hectate site alongside an air force base and the royal palace in 2003 ahead of the inaugural race in 2004, the Sakhir International Circuit’s surface comprises 60 000 tons of highly-prized Graywacke granite imported from England, which offers good grip when clean and is classified medium in terms of abrasion.However, heat management will prove crucial for the cars, tyres and drivers as ambient temperatures regularly exceed 35 degrees and cloudless desert skies push track temperatures towards 60 degrees – amongst the highest of 2012. Such extremes affect tyre wear and result in the drivers dehydrating up to three litres of fluid over the race’s 57 laps.Then there is the sand, lots of it. Desert winds, which switch direction by 180 degree without notice, with obvious effects on top speed and gearing, blow the fine yellow granules on to the track, making it both unpredictably slippery and clogging air intake and cooling systems.Factor in that engines are at full throttle for 70% of each lap and that brake energy is classed as heavy (of eight braking events per lap, five are "high"), and it is clear the 24 drivers face a veritable challenge come 14:00 on Sunday, even without the political distractions which are expected to blight the build-up to the last of two sets of back-to-back flyaway grands prix.A further complication is that the layout for the 2012 race is the same as used in 2009. The longer 24-turn, so-called endurance version was used when last this race was run in 2010. Teams have little up-to-date data (the three new teams have never raced this layout, having entered the sport in 2010) after sweeping changes were made to the technical regulations over the past three years.RULE CHANGESConsider this - KERS in, out, and in again; introduction of DRS; refuelling banned; change of tyre supplier; massive reductions in downforce due to a banning of double decker diffusers and exhaust-blown diffusers; outlawing of F-ducts; introduction of lower noses; and qualifying with race fuel loads in 2009. Thus, although the place is familiar, teams effectively face the unknown.The current 5412km layout has 15 (6L/9R) turns, with the first (left-hander) being absolutely crucial to a good lap time for it leads into long kink before opening into the straight where most positions are won or lost. There are 3 corners taken at speeds of under 100 km/h and one at over 250 km/h, with the lap average coming in at a whisker over 200 km/h.Somewhat surprisingly Pirelli, which entered the sport in 2011 and thus has no experience of Bahrain, has specified a mix of Soft (Yellow) and Medium (White) compounds as used in Australia and the Chinese Grand Prix. Although rain is unlikely, it is not unknown in the region…Equally unlikely are Safety Car interventions. Due to massively wide run-offs and lack of barriers in close proximity to the track, in the seven races held between 2004 and 2010 the silver AMG Mercedes was called out for duty but once, meaning an historical incidence of 14%.For the first DRS race in Bahrain, the FIA has opted for a single drag reduction zone, the activation for which will be ahead of T14, with 650m of main straight being at their disposal before braking for T1.MERCEDES ON A ROLLFernando Alonso is statistically the most successful driver in Bahrain, having three wins from the seven races via Renault (two) and victory in his maiden drive for Ferrari in 2010. Team mate Felipe Massa has two, followed by Jenson Button and Michael Schumacher on one each. Interestingly McLaren has never won in Bahrain despite the team being 50% owned by Mumtalakat, Bahrain’s sovereign wealth fund.Although Ferrari predicts another tough race, Alonso should never be discounted, particularly when the going gets tough, as it is expected to this weekend. However, Mercedes is on a roll and Schumacher, desperate to get on even terms with Rosberg, can be expected to be up there with the McLaren duo of Button and Lewis Hamilton.Red Bull has proven surprisingly lack-lustre, with reigning double champion Sebastian Vettel being out-qualified by Mark Webber three races in a row. A bounce-back is expected sooner rather than later. F1 returnee Kimi Räikkönen reckons Lotus is ready for a podium – so things are likely to get crowded. Traditionally the winner here has come from the first two rows, although the race does not appear to favour pole position. Only three times has the driver on pole won the race. During final analysis, F1 will surely be asking itself how it backed itself into a position where race cars require armed escorts during their 30km journey from airport to circuit.Stay with Wheels24 for the Bahrain Grand Prix weekend.