The travelers duck through a widened slit in a chain-link fence, a makeshift portal to a makeshift train ride above the ruins of the Rockaways. Doctor’s appointments await. So do school days. A grocery store with power. An A.T.M. And so they take their seats to travel through neighborhoods that are still missing many things. But not a subway, anymore. For two weeks now, a so-called H train has been running through a stretch of the Rockaways devastated by Hurricane Sandy, making stops at a limited number of the peninsula’s stations with the help of a connection called the Hammels Wye, which is not ordinarily used by passenger trains.

Ridership is low.

Service disappears for four hours overnight.

Direct connections to other trains are impossible, though a shuttle bus runs from the Far Rockaway-Mott Avenue station, delivering passengers to the A train at Howard Beach, eventually.

Transit officials have said normal A train service in the Rockaways may not resume for several months. The high winds and tidal surge from the storm destroyed hundreds of feet of track; the signal system does not work; track roadbeds were washed away.

But for an area that remains isolated from many critical resources one month after the storm, the free H train shuttle service has been a welcome signal of progress. Plodding, rumbling progress.