REVERE – State Police initially concluded speed was a factor in Wednesday’s tractor-trailer crash that injured the truck driver and snarled Brown Circle traffic for about two hours.The truck crashed onto its right side with its trailer filled with sand, clogging the rotary as emergency vehicles converged. State Police troopers and Revere Police managed to direct stop-and-go traffic from Broadway through the rotary and off American Legion Highway toward Route 107.”Preliminary investigation indicates excessive speed for the rotary was a factor in the crash,” State Police spokesman David Procopio stated.State Department of Conservation and Recreation acting press secretary William Hickey said the truck is one of 30 hauling sand from Saugus off Route 107 to Winthrop Beach. The trucks make 160 round trips daily. Police were escorting the truck to Winthrop when the crash occurred and have been providing escorts since the project began in March.Luis Mendoza heard a loud bang shortly before noon as he waited for his car to be repaired in a shop opposite the crash site. He ran with other people across the rotary’s circular expanse of grass and found the driver dazed but not bleeding.”This is a dangerous circle: Luckily, it was sand,” Revere Fire Department Deputy Chief James Cullen said.Procopio identified the driver as Miguel Hernandez, 23. Initial police scanner reports indicated he was taken to Massachusetts General Hospital. A hospital spokesman said Hernandez was treated and released.G/J Towing sent two large tow trucks to Brown Circle to right the truck and tow it, and workers used front-end loaders and brooms to sweep up the dumped sand.Cullen said the truck is owned by HM Morales Trucking of Chelsea. Procopio said the company is being cited by State Police for defects on the truck including insufficient brake linings, deficient brakes, expired inspection sticker and “cracked air bag supports.”Revere Police Chief Joseph Cafarelli said the crash raises concerns about the sand-hauling operation and said he will call a meeting with agency and business representatives involved in the operation to discuss safety.