Socialism is an ambiguous word, but roads aren't a good example of any of them.

-Does socialism mean the workers own the company? Lots of perfectly capitalistic companies are actually socialist by that standard. I even know a company where the original founder has no equity anymore and everyone else has equity based upon seniority. What socialist would do better?

-Does socialism mean that the government owns the company? Amtrak, Fannie Mae, GM, AIG.... Hasn't been an amazing success so far.

-Does socialism mean that the government provides welfare? By that standard, Bismarck was a socialist. (But in reality, he was an old fashioned aristocrat who figured out you can snip socialism in the bud by using welfare to buy off its supporters.)

-Does socialism mean that the socialist party holds a monopoly on all commerce and politics? We, ah...tried that a few times and it didn't seem to work.

Roads? Most governments build roads, if only for their armies. You think Caesar was a socialist?

Adam Smith gives the example of paying for roads by road tolls in his book The Wealth of Nations. In the United States, much of state and federal funding for highways is derived from a tax on gasoline and diesel vehicle fuel, to much the same effect. The ultimate incidence of ALL taxation is on consumers (and everyone is a consumer), as any competent economist will tell you. These forms of paying for roads are not socialism, by any definition of socialism that I have ever seen, but they are forms of taxation that allocate the cost of using the tax-supported, publicly available resource rather well.

Actually in many more socialist countries, highways and some urban roads are payed by the people who use them. Better examples are military and police force.