Greater Anglia has confirmed that it will be running a reduced service because of threatened snow on Tuesday and Wednesday – and has defended its decision to make a public announcement.

The rail operator announced on Sunday that services on some lines, including Ipswich to Lowestoft and Ipswich to Felixstowe, would be halted altogether and trains on other routes would be slower and less frequent.

It took the decision in consultation with Network Rail and weather specialists who had been predicting very serious conditions.

A spokeswoman for Greater Anglia said: “We didn’t take the decision to cancel services and run an amended timetable lightly. We have been sitting down with Network Rail and meteorologists for several days watching what is happening before this decision was made.

“We are looking at a major weather event which will not only affect us. It will affect roads, power supplies and people everywhere. We felt it was right to give as much warning as possible so people could make alternative arrangements if necessary.”

There has been criticism of the decision on social media as weather forecasts differ on the likely impact of the snow – but the rail authorities believe they could have faced real problems if they tried to run a normal service.

Meliha Duymaz, Network Rail’s route managing director for Anglia, said: “We will be keeping a close eye on the forecast over the next few days and have contingency plans in place for the expected extreme weather.

“Our staff will be working 24/7 to keep main lines open but in order to do this we cannot keep all branch lines open.

“We understand the inconvenience this causes but the safety of our passengers and staff remains our number one priority. We will work to reopen all branch lines as soon as the weather clears.”

Snow and ice can impact the railway in the following ways:

Snow compacted by passing trains can turn into solid ice and prevents points working.

Rails can freeze together which means signals stay red and trains stop.

Heavy snow can make branches break off trees, damaging overhead wires and blocking the track.

Wind can cause snow drifts.