Never heard of I-270.
It’s a commuter route in MD to Washington DC
If you are driving to Washington from points west such as Pittsburgh, Ohio, Indiana and Chicago, you are on I-70 until the city of Frederick, Maryland; at Frederick, there is a major fork in the road—if you stay on I-70 east, in 38 miles you’ll end up at the Baltimore Beltway. If you bear to the right, you end up on I-270, which runs for about 33 miles down to the Washington Beltway.
I-270 is only two lanes in each direction for the first 15 miles from Frederick, then three lanes in each direction for the next 5 miles or so, then almost the rest of the way to the Beltway it is 6 lanes in each direction; a couple of miles north of the Beltway I-270 splits—bear to the left and end up in Bethesda near the famous naval hospital (the complex is now known as Walter Reed); bear to the right and end up near the American Legion bridge leading into Northern Virginia.
I’ve traveled on this highway for close to 40 years. The traffic jams on this route occur every day and are horrendous. If you want to keep your sanity, you need to drive on this route only between 10 am-3 pm and between 8 pm and 5 am.
The powers that be in Maryland have known about the congestion problems for that long, and, because of environmental whackism in Montgomery County and the fact that Frederick County doesn’t have all that much clout in Annapolis, nothing has been done about it.
There are now three segments of HOT (high occupancy toll) lanes in the DC-Baltimore area: (1) about 10 miles of the Washington Beltway between Springfield and McLean, VA; (2) the newly opened I-95 Express lanes (which are actually reversible lanes in morning and evening rush hours, that run almost 30 miles from the Alexandria/Fairfax Co. line south beyond Aquia in Stafford Co.; and (3) on I-95 in Maryland north of Baltimore, running out from the Baltimore City line to around Joppa (south of exit 74).
These are so-called PPPs (public private partnerships), where the state contracts with a major highway builder (in Virginia, they used a company called Trans Urban, a subsidiary of the giant contracting company Fluor), which built the HOT lanes and gets most of the toll money for a period of time (I think 40 years). One gimmick they are using to get people to drive on the HOT lanes in VA is to have a higher speed limit (on the Beltway, you can go 65 in the HOT lanes, 55 in the regular lanes; the lanes are separated by pylons).
Thus the state gets bigger road capacity without a major capital outlay on their part.
Three lettered I roads are usually perimeters, beltways, or spur lines. Two lettered I roads are interstate, generally. Of those, odd numbered are North/South and even are East/West......Useless trivia I guess.
Goes between the DC beltway and I-70.