Depending on where in G/town and where in BAL this is possibly doable. If you live near a Circulator stop, it is about 25 mins to Union Station where you catch the MARC train to Baltimore Penn Station (abt. 55 mins). From there, depends on where you work whether you walk, bus or light rail. Thus, allow 1:20 + the local Baltimore commute in each direction. Note that MARC service is limited in the evenings, non-existent at night and weekends. Amtrak covers the same route, but it's exceedingly expensive (for commuting).