NEW YORK (PIX11) — Delays and detours can stop commuters in their tracks.

As more people return to the office and as ridership increases, be on the look out for slow downs. Monday saw a slow start on a number of subway lines during the morning commute.

Signal problems, passengers in need of attention, track issues, brake activation, power issues and police investigation are some of the common reasons for delays. Each month, statistics on delays are included in materials provided to the NYC Transit committee.

The numbers from February show delays caused by external factors are increasing.

Crew shortages due to COVID had accounted for many delays but those are declining. People on the tracks and in tunnels along with track fires have been a concern recently.

On Sunday, service on the No. 7 subway line was shut down between Hunters Point and all Manhattan stations. Sources say a metal utility door ended up on the tracks. MTA officials are investigating.