Formula One test circuits have made huge improvements in safety since drivers raised concerns last year, Italian Jarno Trulli said on Friday.
"You cannot imagine such a big step that we have done in the last six months," the driver told reporters at the launch of the new Toyota TF107 car that he will test for the first time later this month.
"A circuit like Jerez has made a huge, huge step on safety," he added. "Before they were really poor in all details and now I feel much more comfortable.
"There are still some tracks that have to make a little effort in order to be safer, but this I think is a great achievement by the GPDA (Grand Prix Drivers' Association), by the teams and (governing) FIA.
"Before there were no rules and you cannot imagine the situation that we were testing in. It was really, really bad. At the races everything is fine but at testing it really was a disaster," said the Italian.
Formula One teams test at various circuits over the European winter, although mostly at Barcelona, Jerez and Valencia in Spain because of the warmer conditions.
Testing has been cut back significantly this year, however, in an agreement between the teams to cut costs now that there is only one tyre provider.
Brazilian triple champion Ayrton Senna was the last Formula One driver to die in a race, at the 1994 San Marino Grand Prix.
However drivers have become increasingly concerned about the dangers of a big accident at private test sessions held at deserted circuits often ill-equipped to cope with a medical emergency.
Australian Mark Webber, now one of the GPDA's three directors, had warned last May that drivers lives were being put at risk.
"We are a decade behind where we should be," he said.
"Testing is probably the most dangerous part of our job because we are testing new things. Things do fail in testing, we are testing tyres to the limit, we are testing wings and suspension and things and sometimes the engineers do make mistakes and there are crashes.