Getting directions on the road from Google Maps and other smartphone apps is a popular alternative to the expensive navigation aids included in some cars. The apps are also a gray area when it comes to laws banning the use of cellphones or texting while driving. The Transportation Department wants to enter the argument. The department is intensifying its battle against distracted driving by seeking explicit authority from Congress to regulate navigation aids of all types, including apps on smartphones. The measure, included in the Obama administration’s proposed transportation bill, would specify that the National Highway Traffic Safety Administration has the authority to set restrictions on the apps and later order changes if they are deemed dangerous, much the way it currently regulates mechanical features of cars.