SAN DIEGO (CNS) - Trolley service between downtown San Diego and San Ysidro resumed normal operations Tuesday morning following a day of delays caused by inoperative signals along a several miles of tracks.
   
The roughly 20-minute lag times Monday were due to ''signal improvement work which was not completed by a contractor over the weekend,'' and forced the trams to slow down in the affected area, Metropolitan Transit System spokesman Rob Schupp said.
   
MTS announced via Twitter shortly before 7 a.m. Tuesday that normal Blue Line trolley service had resumed.