HOUSTON, Texas -- An accident involving a big rig is causing major delays near downtown Houston.According to a spokesperson with the Texas Department of Transportation, a truck struck an overpass along I-10 at I-45, just north of downtown.A Department of Public Safety crew is on the scene assessing the situation to determine if there's any structural damage to the connector road.Westbound traffic on the Katy Freeway is extremely slow in the area. The situation is expected to take some time to clear up.