Depending on traffic, getting from Pittsburgh Int'l Airport (PIT) to Carnegie Mellon can take from 25 minutes to an hour or so. Plan on 40 minutes for a late-morning PIT-to-CMU trip, and an hour for the return CMU-to-PIT trip (it may take much less than an hour, but the Fort Pitt tunnel, through which you must go unless you are a native Pittsburgher who knows whacky alternatives, is an unpredictable bottleneck).
To begin, go to Google Maps, use PIT (airport code) as the origin and 5000 Forbes Ave, Pittsburgh, PA, 15213 as the destination, and you will get a terse approximation of how to find Carnegie Mellon. Unfortunately, the map won’t tell you all the landmarks, or which lane you need to be in. These details follow.
As you exit the airport, you will want to be in the second-left-most lane, to get onto the ramp toward Pittsburgh, on route 60. (The left-most lane will return you to the airport.) You will remain on this road all the way into Pittsburgh, although it will become route 22 at some point, and then will become I-279 after you have crossed I-79 (I-79 runs north/south and connects Erie, PA to Morgantown, WV—you do not want to get on I-79). Depending on traffic, this part of the trip can take anywhere from fifteen minutes to half an hour or more.
As you approach the Fort Pitt tunnel into Pittsburgh, you will see a runaway
truck sandpile ramp on your right side; at this point, you will want to be in
the right lane—watch for signs over this lane saying I-376 East, Monroeville.
Stay in this same lane as you go through the tunnel; stay in this
same lane as it turns to the right and becomes the beginning of I-376 East;
and in fact stay in this same lane until it becomes the “exit only”
lane for Forbes Ave./Oakland, which is the
exit you want: Forbes Ave. goes to Carnegie Mellon; Oakland is the Pittsburgh
neighborhood in which Carnegie Mellon and the University of Pittsburgh are both
located.
Once you are off of the exit ramp and actually on Forbes Ave., shift to the middle lane, and stay in this lane (apart from dodging delivery trucks and busses) until just before you enter the driveway that will lead you to the building in which the Auton Lab is located. As you approach the first traffic-lighted intersection (with Craft Ave.), you will see a skyscraper directly in front of you, the University of Pittsburgh’s Cathedral of Learning. After several blocks, you will pass under a University of Pittsburgh pedestrian bridge, and Forbes will bend to the right; shortly thereafter, you will see a park-like area with the Cathedral of Learning on your left, and ahead and to the right you will see the enormous bulk of the Carnegie Library and Museum complex. Continue in the same lane, straight on Forbes, past the Diplodocus (harmless), the Natural History Museum (old), and the Museum of Art (somewhat newer, with a glass front at ground level, although perhaps so blocked by school busses that you’ll be unable to tell), until you reach the intersection of Forbes Ave. and Craig St., just past the Museum of Art. This is a very busy intersection, and you may have to temporarily duck into the right lane to get around vehicles turning left onto Craig.
Just past Craig you will see a few small restaurants and shops on the right and then you will cross a bridge. Continue straight through the light in front of Hamburg Hall. Drive a little further and you'll pass through the intersection of Morewood and Forbes. After the bus stop on your right you'll see the East Campus Parking Garage - you will want to park here. You have arrived on the Carnegie Mellon campus, a collection of mostly pale-yellow-brick-and-green-metal-roofed buildings.
Once you leave the garage on foot you will want to head down the hill towards the Morewood and Hamburg Hall intersections. Just past Hamburg Hall and before the Collaborative Innovation Center you will see a driveway on your left. Follow the driveway back until it turns to the left, and you will be in the parking lot between Smith Hall and Newell-Simon Hall. (See the diagram on the next page for these final landmarks.) Smith Hall is an older building that says "Smith Hall" over its door; Newell-Simon Hall, in which the Auton Lab is located, is the newer and strangely anonymous building directly opposite Smith Hall, with several bike racks on the right as you approach its doors. (Carnegie Mellon has a beautiful campus, by the way, complete with trees and lawns and occasional art: you just can't tell it from the vicinity of Newell-Simon Hall.)
Enter Newell-Simon, and take the first door on the right, "Corridor 3100." Artur Dubrawski is in office 3121, and Jeff Schneider is in office 3117; Auton Lab grad students, post-docs, and programmers occupy several other offices in the same hallway.

From the parking lot’s driveway, turn left onto Forbes. After Craig, make sure to be in the left lane on Forbes, so that when you turn right onto S. Bellefield Ave. (you won’t have a choice), you will be able to get into Bellefield’s left lane easily. Turn left onto Fifth Ave (which parallels Forbes, one-way in the opposite direction), and get into the second-to-left traffic lane (which is third-to-left from the curb: the leftmost lane is a bus lane). Stay in this lane past all of the U. of Pitt. buildings and hospitals, all the way to Craft Ave. Just before Craft Ave., you will see signs for I-376—you want I-376 West. Just past Craft, you will see that Fifth Ave bends to the right, but you need to turn left, downhill, on Craft, and make sure you are in the right lane on Craft. At the next light (bottom of the hill), turn right onto Forbes, and immediately right onto an on-ramp (you won’t have a choice); there is a stop sign at the top of this on-ramp, so traffic is usually slow here, almost any time of day. Turn right at the stop sign, preferably without being run down by a truck, and remain in the right lane: this lane will soon become an on-ramp for I-376 West/Downtown/Fort Pitt Bridge. Once on I-376, get in the middle lane; when you see the sign saying I-279 South/Fort Pitt Bridge/Airport, shift into the left lane, and remain in this lane back through the Fort Pitt tunnel. Because of the hills, traffic is often challenging in places, but you should find the airport with no trouble from there.
— by John Ostlund