A snowstorm that swept over Northern Virginia on January 9 caused trouble for commuters—and a massive pile-up for cars on the highway.According to Virginia State Police, the trouble started early Saturday when a collision between a truck and a tractor-trailer occurred suddenly on I-95, near Dale City.Due to icy roads and blustery weather conditions, the vehicles following those in the crash were unable to stop, swerve, or avoid becoming part of the accident. The increased speed on the highway combined with the harsh weather caused a chain reaction of fender-bender accidents as cars struggled to brake quickly.When the action stopped, police estimated that some 52 vehicles had been involved in the accident. Traffic was rerouted as the packed southbound lanes were cleared with the use of HOV lanes.Despite the number of vehicles involved in the collision, no fatalities were reported. Only four people sustained injuries as a result of the accident. Police report that the injured were taken to a nearby hospital for treatment of minor injuries and are expected to fully recover.The slippery roads and decreased sight distance from the storm may have contributed to another multi-vehicle accident on northbound I-95 that same morning. Police and rescue crews also responded to this accident, although fewer cars were involved.The original cause of the southbound accident is still under investigation.