Q: “Why the hell does it take a Metro North train 15 minutes to get from Grand Central to 125^th Street?” 

A: Actually, it only takes 10 minutes (check any schedule) but it can seem like 15 minutes or even longer. The distance covered is actually 80 blocks (45th Street, which is roughly where the nose ends of the train are on the GCT platforms, up to 125th = 80 blocks.) And that’s four miles. First off, because a passenger sees little more than blackness outside the window, his sense of distance and time can become a little impaired. Still, 10 minutes to go four miles is only 24 m.p.h.—truly a crawl when you consider that even subways can hit close to 60 m.p.h. under the East River. So what gives with the delay? The principal reasons are two. Reason No. 1: Even though the complex was completed back in 1913, Grand Central’s trackage still constitutes the largest interlock in the world. You’ve got 41 tracks on the upper level, 26 on the lower—plus various layup tracks and sidings. All of these tracks eventually merge into a four-track mainline on one level just below street, which becomes the south end of the Park Avenue Tunnel.  Okay, so you’ve got all of these tracks moving up toward a bottleneck—crossing and converging in an ever-narrowing space. A switch governs each spot where two tracks meet, and here the train wheels have to roll over a small but significant gap in the rail. A train MUST go slowly when it crosses a switch, or the train could derail. And so, because the trains cross scores of switches on their way north, they CRAWL through the interlock—and that takes time. The tracks finally converge into the four-track mainline at roughly 51^st Street, but that’s six city blocks’ worth of switches that a Metro North train must navigate. If you’d like to see just how incredibly complex the GCT interlock is, go here for a look at the upper-level schematic:  http://en.wikipedia.org/wiki/Image:RailUS_GCT-upperTracksPlan.gif 

If your train happens to be departing from the lower level, the trip can take even longer. Why? Because the train has to literally climb a ramp to the upper level. Most mainline railroads avoid grades steeper than 2%; the inclined tracks that climb between levels in Grand Central range between 2.6% and 3%. This is a difficult climb for a train, even an electric one, and it takes a while.  Reason No. 2: Once your train has finally made it out of the interlock, another delay arrives to ruin your evening. In railroad parlance, you’re under a “speed restriction.” This will slow up the rate of your train for the next several miles. The restrictions are tightest within the Park Avenue Tunnel, but the reason for any speed restriction is the same: Safety. The slower a train is moving, the less chance it stands of colliding with another train. And the sheer number of trains you’ll find in the Grand Central complex at any given time is going to be far greater than what you’d see at most points up the line. Think about it: At poor old Purdy’s, for example, you might see two trains an hour, one northbound and one south. But at peak rush down at GCT, you might have a train coming in or leaving every five minutes. From the earliest days, then, back when the New York Central Railroad operated the line now known as Metro North, the GCT track region has been under speed restrictions that become progressively stricter the closer a train gets to the terminal itself. I’m using an old-time manual for the following numbers, and the speeds may have changed a bit—but the concept remains the same. A train moving anywhere between Woodlawn and Melrose in the Bronx is free to go up to 60 m.p.h., but on the stretch between Melrose and 62^nd Street inside the Park Avenue Tunnel, the speed limit is 35 m.p.h. If a train is operating anywhere below 62^nd Street—in the tunnel or within the interlock itself, the speeds are between 6 and 10 m.p.h.  But next time you’re on your train leaving GCT, take note of the change in speed restriction zones. Once your train reaches 62^nd Street (easy to find, because there’s an emergency exit platform at 59^th Street that’s lit up), you’ll notice that you’ll start moving at a nice clip. By the time you blow out of the tunnel’s mouth at 98^th Street, you’re going far faster than you had been back when your train was navigating the interlock. Still wanna know more? Speed are further restricted via what’s known as the “block” system—used in most all railroads—that operates on a simple principle: If you wish to avoid collisions (and who wouldn’t?) two trains cannot be in the same spot at the same time. A block, then, is a stretch of track inside which only one train can be at a given time. During peak hours at Grand Central, when you’ve got many trains having to share a mere four tracks in the Park Avenue Tunnel, it’s much more likely that one train will get too close to the block that another train is in. If it does, it has to slow down. Within the interlock and the Tunnel, blocks are easy to see. Stand in the head-end car and look out the front window and you’ll notice devices that resemble traffic lights that are bolted to the right-hand wall or standing freely on the same side. Each block of track is marked off by one of those banks of lights. If the light is red, it means there’s a train in the block ahead of the one your train is in—and the motorman must stop the train before he reaches the light. (If he runs it, by the way, he’s looking at one week’s suspension without pay, at the very least.) If the light is yellow, your train must slow down because the train ahead of you is just leaving its block. And if the light’s green, well, you’re free to roam. And so, your train’s speed as it departs GCT can also be affected by the number of other trains operating in the same area. Because the trains must remain at least a track block apart, slow-downs are inevitable. More recently, signal blocks have been augmented by the “cab signal” system. Instead of watching out for lights, the motorman listens for a rapid series of beeps that sound in his cab should his train be getting too close to another train ahead. The beeps or the lights are both triggered electrically by a system that senses a train’s presence within a given block through the axle that connects both tracks to form a circuit. If you’re sitting near the cab in the head-end car, the beeps are easy to hear, and when you do hear them, you’ll notice that your train will immediately slow down. Be it cab signal or block signal, the idea’s the same: keep the trains apart. But keeping them apart often means delaying them—and that adds time to your commute. And that, those of you who are still awake, is why it takes 10 minutes to get from Grand Central to 125th Street. —Engine Bob