WARSAW, Poland - The deadly train collision that left 16 people dead has put the spotlight on Poland's long-neglected railroad system, which officials are scrambling to develop as they prepare to co-host one of Europe's biggest sporting events this summer.

As prosecutors on Monday announced plans to charge a traffic controller with unintentionally causing the spectacular crash that also injured more than 50 people, experts and officials in Poland insisted that trains remain the safest form of travel in spite of Saturday's tragedy.

But, some railway employees accused the state-run rail system of cutting back on security precautions as it tries to cut costs.

The rail network and the rest of the country's infrastructure are in a state of profound post-Communist transformation as the new European Union member uses subsidies to upgrade rail tracks, lay motorways and turn some of its dilapidated train stations into shiny modern hubs.

Authorities are putting more trains on the tracks and adding new connections for some of the 700,000 to 1 million fans expected to travel to Poland for the Euro 2012 soccer championship, which Poland and Ukraine will co-host from June 8-July 1.

Experts say that railway remains the safest form of travel, pointing out that the accident, which left the first cars of the two trains a heap of mangled metal, was the mostly deadly in 22 years in Poland and extremely rare.

Human error emerged on Monday as a possible cause of the crash outside the southern town of town of Szczekociny, just north of Krakow. Prosecutor Tomasz Ozimek said he plans to file charges against a railroad traffic controller responsible for setting the mechanisms routing the trains, and is suspected of sending one the wrong way down the track at high speed. A second controller was also detained for questioning but hasn't been charged.

The Gazeta Wyborcza newspaper, a leading daily paper, accused consecutive governments over the past 20 years of denying funds for improvements in the network. "Something else was always more important," the paper wrote in an opinion piece.

Yet some of the harshest criticism came from railway employees.

"Unfortunately, sometimes economy takes the upper hand over safety," said Aleksander Motyka, head of a controllers' union. "A controller needs to do maintenance and other work in the station, or even sell tickets" as efforts are made to save money.

Experts describe the Polish railway sector as under constant upgrade work as it struggles to catch up with levels in the West, making train travel unnecessarily slow. Still, they say it is safe.

Travel by car and bus is much more dangerous. Statistics show that there have been around 5,500 deaths per year on the road in recent years across this nation of 38 million, where drivers often speed and attempt dangerous overtakings on two-lane roads.

"In Poland, as in Europe, trains are the safest means of transport," said Marek Sitarz, head of the Rail Transport Chair at the Technical University in Katowice.

"Accidents happened and will happen everywhere but this crash will make those in charge look closer at the procedures," he said. "Soccer fans should feel safer now, because even more attention will be given to train travel."

The Polish rail sector is 20 years behind where it should be, in part due to a lack of investments in the early years after Poland established a market economy in 1990, said Katarzyna Bednarska, an analyst who studies the rail construction sector.

Only in 2007, three years after Poland joined the EU, did large subsidies began flowing in to upgrade the network, an effort accelerated by preparations for Euro 2012.

Bednarska says that despite the modernization efforts -- aimed at upgrading trains, tracks, and other technology -- only 36 per cent of about 19,000 kilometres (11,800 miles) of railway lines in the country are in good condition.

Speeds above 160 kph (99 mph) per hour can be achieved on only 6 per cent of the lines.

Some 700 kilometres will have been upgraded at the cost of some 9 billion zlotys ($3 billion) by the time the championship kicks off, according to Piotrowski.