A noontime wreck today in the 3200 block of Barksdale Boulevard sent both drivers to the hospital and snarled traffic for more than two hours.  Bossier City police say a Toyota Tacoma pickup truck was northbound around noon when it drifted into the opposing lanes of traffic and collided head-on with a southbound Nissan Altima sedan.  Both drivers were rushed to LSU Health with what were described as serious but not life-threatening injuries.  Traffic Investigators say alcohol is suspected of being a contributing factor to the wreck.  Traffic on Barksdale Boulevard was hampered for a little more than two hours until the investigation was completed and the wreckage hauled off.