A damning report by MPs accuses the infrastructure body of smearing victims as trespassers and warned it should aim to cut the number of deaths at level crossings to zero by 2020.
Nine people were killed on level crossings in Britain in 2012/13.
Louise Ellman, chairwoman of the Commons Transport Select Committee, said: "Every one of those deaths was a personal tragedy which could have been averted. Yet looking back it's clear that on too many occasions Network Rail showed a callous disregard for the feelings of the families of people killed or seriously injured in accidents at level crossings.
"Victims were erroneously described as trespassers or accused of misuse of the railway when, in fact, they tried to use level crossings appropriately.
"Network Rail's chief executive must provide a full, public apology to all of the families it has let down - both for the mistakes which contributed to the accidental deaths and for the subsequent treatment of bereaved families."
A number of collisions have highlighted the dangers of open level crossings. Among them were the deaths of Angus and Margaret MacKay, both 81, and Angus's brother Donald, 66, who were killed when a train struck their car at the Halkirk, Caithness, crossing in September 2009.
Their son Donald MacKay successfully sued Network Rail over alleged safety breaches, insisting his parents may still have been alive if a barrier had been in place.
Last night, Mr Mackay, of Inverness, backed the findings. He said: "Network Rail have never liked to own up to their responsibilities in terms of level crossings.
"They seem to have an incredible attitude to what they're supposed to do and their attitude to anyone who has the temerity to use their crossings and get caught on them is frankly appalling.
"I think that the politician who has come up with this statement has hit the nail on the head. I utterly welcome it as it's something that needed to be said."
Today's report states Network Rail must improve communication with bereaved families and urges ministers to consider whether it and its employees should be bound by a "duty of candour".
It faced criticism for withholding key risk assessment documents from the inquest into the deaths of two teenage friends in Essex. Olivia Bazlinton, 14, and Charlotte Thompson, 13, were killed on a level crossing in 2005 in Essex, three years after a risk assessment recommended it be fitted with new gates that locked automatically as trains approached. They had not been installed.
The case was "particularly shocking and raises profound questions about Network Rail's internal culture", said Ms Ellman.
Network Rail bosses admitted their management of level crossings had been negligent at the time of the Essex crash, describing the incident as a watershed moment.
However, in June last year Network Rail were fined £500,000 for health and safety breaches after a 10-year-old boy was seriously injured on an unmanned level crossing in Suffolk in 2010.
There was no phone to allow the driver of the truck in which the youngster was travelling to check when the next train was due. Ms Ellman said Network Rail's executive directors should forego bonuses this year in light of the case.
Mark Carne, the newly appointed chief executive of Network Rail, offered a "full and unreserved apology" for failings made by the company. However, he said British level crossings were now among the safest in Europe after millions were spent on them.