Some 48 percent of train drivers are taking part in the strike, which has been dubbed "Black Tuesday" by the French press.
While French business leaders and economists welcomed the plans, several unions have strongly criticized the proposals.
Air France workers also went on strike over pay today, although the company said it expected 75 per cent of flights to operate as usual.
The unions appear weaker now, however, and are divided over their responses to Macron's many social and economic reforms.
Despite the planned rolling strikes by rail workers, Macron plans to push through the SNCF overhaul by executive order, which will allow him to avoid parliamentary debate. He has already stared them down over easing labor laws.
Speaking to parliament, prime minister Edouard Philippe said the way the SNCF operated could not continue.
"This government has had an easy time so far, but this is a real political battle." former transport ministers Dominique Bussereau, who supports the government reforms, said on France2 television. "I respect the strikers because going on strike is a constitutional right".
Russia expels 59 diplomats from 23 countries as spy crisis escalates
Ministry spokesman Maria Zakharova said there was no explanation given for the search, which she called "the latest provocation". German Ambassador to Russia Ruediger von Fritsch leaves the Russian foreign ministry building in Moscow , Russia March 30, 2018.
The CGT has called for public and private sector workers nationwide to strike on April 19, but in a sign of union division, private sector unions have so far declined.
"I want to be very clear. the strike action will no doubt be widely adhered to and is going to make the lives of a lot of people very hard", SNCF boss Guillaume Pepy said in a radio interview, as quoted by Reuters. Under government plans, these historical benefits would not be applied to new rail staff. "The salaries aren't wonderful, the work conditions are hard, and for some it means working every other weekend". An Ifop poll on Sunday showed that just over half of French people view the strikes as unjustified.
Mr Macron wants to transform the SNCF into a profit-maker.
Labour unions plan their biggest protest against changes at SNCF, the indebted national railroad, where Macron plans to deny future hires the job security, early retirement and special pensions of existing workers, while opening up train lines to competition.
Borne has sought to ease tensions with assurances that current SNCF employees that have to move to a competitor in the future would keep most of their advantages. Nearly 80 per cent of SCNF workers are on strike on Tuesday and Wednesday.
The Communist-rooted CGT wants the strike to spread beyond the rail sector. However little impact was felt in the power sector and on nuclear-reliant France's 58 nuclear reactors operated by state-controlled utility EDF.
Those actions get on the majority of reasonable of the ones at Air France the area employees are testing a 6 symphonious with cent pay higher drive as well as function been putting for the staying 4 days.