According to the Maryland Department of Transportation, the work on the Gateway project will be concentrated on the inland states rather than Maryland.  Here's the project description from MDOT:

Project Description:
The National Gateway Project is a package of rail infrastructure and intermodal terminal projects that will enhance transportation service options along three major freight rail corridors owned and operated by CSX through the Midwest and along the Atlantic coast. The improvements will allow trains to carry double-stacked containers, increase freight capacity and make the corridor more marketable to major East Coast ports and shippers. TIGER funds will help complete the first corridor project, from Northwest Ohio to Chambersburg, Pennsylvania, through West Virginia and Maryland.

Highlights:
•        Doubles rail capacity on a major freight rail corridor with no increase in noise, emissions or train length
•        Promotes rail as a cost-effective alternative to long-haul trucking, reducing greenhouse gas emissions and the Nation’s dependence on oil
•        Saves in shipper and logistics costs and significantly increases freight capacity
•        Significant portions of the investments in this corridor are in economically distressed areas

The Washington area transit project is expected to go a long way toward speeding bus travel in that region. Here's MDOT's description:

Project Description:
The project will provide more efficient bus service along 13 transit corridors in Maryland, Virginia and Washington, D.C., by investing in a bus transitway, bus-only lanes, transit signal priority, traffic signal management, real-time arrival technology and other enhancements. TIGER funds will be used to construct a new transit center at the intersection of University Boulevard and New Hampshire Avenue on the border of Montgomery and Prince George’s Counties in Maryland which will consolidate scattered bus stops at a heavily used bus transfer point into one facility. TIGER funds will also provide station improvements (bus bays, real time bus information and other improvements) supporting bus priority on the I-95/395 corridor.

Highlights:
•        Significantly improves the performance of the region’s transportation network, providing more choices to more travelers, including low-income and transit-dependent residents
•        Reflects extensive, multi-jurisdictional planning efforts
•        Many of the areas to be served by these projects are economically distressed areas.