Questions about getting around the city? E-mail transit@nysun.com

Q: There are signs on no. 4, 5, and 6 lines that say the MTA is doing work and to expect delays, even during rush hour. The signs also say that this is a very rare occurrence. How rare is it? And what is the work that is so vital it causes delays even during rush hour?

A: The usual weekend subway reroutings tend to be caused by either station rehabilitation or signal work. Sometimes, part of the routine maintenance includes wholesale track removal. On less-traveled routes, New York City Transit can close the line and use shuttle buses. But for a highly trafficked route, NYCT can’t just stop the train. Too many people use it, even on weekends.

Not only are nos. 4 and 5 getting new rails, engineers are replacing the decaying concrete and gravel that forms the rail bed, called ballast. To do that, they rip up the old rail and put temporary rails on slats of wood that stand slightly above the ground, but keep the rail at the same height as the original. These temporary supports, known as “skeletal rails,” are safe at low speeds, which is why the nos. 4 and 5 run on a delay during rush hours. During normal periods the gaps between trains are longer and the slower pace has less of an impact on schedules.

At nights and on weekends, engineers will excavate the old ballast and pour new concrete and gravel, lay the railroad ties, and finally rivet new steel rails to the ties. The end result is a better, safer ride, though it is a bit of a hassle now.

NYCT is working south from Grand Central Terminal to Brooklyn Bridge Station. It expects to be done in September.

Q: I understand why we can’t park in front of churches on Fridays, but with the city in such desperate need of parking, why can’t we park in front of churches the rest of the week?

A: Apparently, this is not a new question for the New York City Department of Transportation. Its chief spokesman, Tom Cocola, wrote in an e-mail, “It should be noted that people associate Sundays with churches, but churches are indeed involved in many daily activities. (In fact, my Catholic church offers daily Masses, as do virtually all others.) In addition to daily Mass, funerals are conducted on weekdays, and some churches also may have special gatherings or even summer-camp related programs near their grounds. Obviously, Saturday is an extremely busy day for churches, as funerals, weddings, and Saturday evening Mass is offered – not to mention Confirmation or Communion events.”

Other houses of worship receive the same treatment. Jewish synagogues have weekly worship on Saturdays, and Muslim mosques have worship five times a day, seven days a week. The city makes its regulatory life easier by creating a blanket parking rule for all of them, rather than trying to tailor parking bans to each religious group.