Eurail passes have been a constant in European travel for more than 50 years, but the details keep evolving. Here's what is new for 2013:

Turkish rail: The latest addition is Turkey, which became part of the Eurail Global and Eurail Select pass lineup at the start of this year. The Global option is the current version of the original "valid on all the participating systems" concept, and the addition of Turkey raises the total number of countries to 24.

The Global option is available in two versions: "continuous" covers 15 days to three months of consecutive-day travel starting any time during the three-month period, and "flexible" provides 10 or 15 travel days over a two-month period. Select passes cover three to five adjacent countries, with a wide range of dates. The Select option covers almost all possible combinations of three, four, or five adjacent countries, with flexible versions for a range of traveling days.

For now, the Turkish railway system is not well geared to international visitors. The system is building two high-speed lines, linking Ankara with Istanbul and Konya, but the Ankara-Istanbul line is only half-completed, and as far as I can tell, the railroad is not currently running through trains.

Moreover, the rail system doesn't serve either the popular Antalya or Pamukkale regions well. Currently, the only all-rail connection with the rest of the Eurail network is through Bulgaria. International trains linking Turkey with Greece are currently suspended. Ultimately, when the new high-speed lines are completed, the Turkish rail system will be very useful. For now, if you're visiting Turkey, plan on flying or taking buses.

Austria's Westbahn: The private Westbahn railway in Austria has also joined the system. That line provides express services between Salzburg and Vienna, in competition with the state system. According to RailEurope, Westbahn is the first such private line to join the Eurail group.

The emergence of private lines on major European rail systems, under the "open access" provisions that are becoming more widespread, raises a challenge to the Eurail group and users of its passes, depending on whether the private systems elect to enter the system. And not all private lines join: The new Italo high-speed trains I tested last year have not joined. If other private lines do not join, opportunities for pass-users might get a little tighter as the established state railways lose market share and cut service on competitive routes.

A change in France: This year's main loss is in France, where the SNCF has opted out of the "Select Pass" program. However, France will stick with its various two-country passes, as well as the single-country France passes and the multicountry Global passes.

Contact Ed Perkins at eperkins@mind.net.