Q: If I want to go on an out of city bike trip this weekend, do I need a permit to bring my bike on a train?

A: It depends where you go. For the subways: no permit is required. Once you head out of the city, however, you will need a $5 permit to bring your bike onto Metro-North and Long Island Rail Road trains, although folding bikes are allowed on the LIRR. Neither PATH nor New Jersey Transit requires a permit, though both forbid bikes on rush-hour trains. Private bus lines vary but city buses do not allow bikes. Visit www.bikemap.com or www.transalt.org/info/aboard.html for more detailed information.

If you do take your bike on the subway, know the rules. Much has been made this week about new rules for subway riders, including clarifications for bicyclists. Those rules have not been adopted, so for now, at least, it is still legal to straddle your bicycle on the subway – though you can be given a ticket for riding it on a platform or subway.

Q: Why can’t the subway get those digital signs that tell you when the next train is coming?

A: Those signs are coming this fall, along with the computerized trains, at select stations along the L line. The first segment of the L, from Broadway Junction to Rockaway Park, will be running Computerized Based Train Control, New York City Transit’s first attempt to phase in computerized trains on that line. The digital signs will be a byproduct of the new technology.

The next line to be transformed into a computerized train will be the no. 7, but work is not scheduled to begin for at least another 18 months, a New York City Transit spokesman, Charles Seaton, said.

Meanwhile, digital signs with arrival information will also come to 15 bus stops within the next 18 months. On Monday, transit officials approved a contract with Siemens to begin installing bus location technology on 185 city buses that will also communicate with bus stops to let riders know how soon buses will arrive.

The $7.2 million program will pay for buses that originate from the 126th Street bus depot at Manhattanville, and travel the M15, M31, M35, M57, M66, and M116 routes, to be equipped over the next 18 months with software that transmits the bus’s location. The software will also allow dispatchers to monitor the bus during an emergency.

Another technology, affectionately called On-Board Next Stop Annunciation, will announce the next stop to riders verbally along with a written display, much like the R142 subway cars introduced in 2000 on the Lexington Avenue line.

The contract for the buses was paid for in part by the Federal Transit Administration and awarded following a pilot program on the M15, a bus route that carries 61,000 riders daily and originates in East Harlem. Eventually, all 4,600 city buses are to have the technology.