While measuring a course today that starts and finishes on a track I noticed something strange about the turns on the track. Below is a picture of one of the turns.

The line is the inside of lane 1, and that other line, 30cm inside the lane 1 line, is the groove where the curb fits. Huh? So they put a curb around the track but you aren't allowed to run right next to it?

I checked, and the width of lane 1 is the same as all the other lanes, and the 400m stagger for lane 2 is the half the 400m stagger of lane 3.

This groove is actually only on one end of the track, which would indicate that it is old and the track as been relined since. But did they shift the whole track 30cm to the south when they relined it? Maybe it has something to do with changing from 440y to 400m.

Anybody want to try to make sense of this? Am I missing something?
Original Post

The curb seems to be located in the proper position relative to the inner line, but its absence in part of the circuit indicates that it’s a relic of the past. What remains of it does indicate that the present lap length is consistent with the lap length before restriping.

In the few times I’ve had occasion to look at a track, I have found that the owners generally cannot find any documentation as to track length, assuming that they received it when the track was built.

I wonder how acceptance of a track record actually works. Is any proof of accuracy required when application is made for record recognition?
But the curb shouldn't be 30cm inside the inside line, it should BE the inside line. If it is a remnant left after restriping, it would mean they shifted the entire track 30cm to the south. On the turn at the other end of the track the groove would have had to have been in the middle of the current lane 1, so they removed it.

The track is in the link below. You can open it in Google Earth, but even in Google Maps you can see the double inside line on the south turn.

http://tinyurl.com/3jwsrkd
Having the curb support 30 cm inside the inside lane line allows meet directors to use the inside line as the inner boundary, if the curb is absent, or use the curb if it is installed. I cheerfully admit I find this a bit confusing.

Most of the few tracks I have seen don't have the curb installed, as it gets in the way of football, and it's no small job to install the curb.
If you were going to set it up the way you say, where the track is the correct length both with and without the curb, then wouldn't you want the curb to be 10cm inside the inside line? This is the difference between the curb and no curb measurement offset.
You're right! I've been off base.
It appears that this might be the water drain.
Most tracks (all should have them) are built with drainage - some are more obvious then others.
It is also standard when building a track to have approximately 30+ cm of rubber surface from the left lane line towards the infield. Amoung other reasons, this is done to give the ensure that the measured track (by the surveyor) will actually fit on the rubber! You should also find some additonal rubber on the outside of the outermost lane.
One of the obvious problems with curbless tracks is that runners tend to run on the inner line or even across the line thereby running short.
That's why American and World track records can't be set on a track without a curb.
Ha ha. David that's probably what it is! This south turn is the only place where it exists, and I believe this is also the only place where the inside of the track borders another area of paved surface.
I made the assumption that it was for curb installation because it was that magic 30cm inside the lane. Based on everything else though, a drain makes a lot more sense.
David, many thanks. I'd seen some drains but didn't pay attention, and assumed, like Mark, that the drain was actually a socket for curb segments.

Now that I think about it, the track curb segments I've seen seem to have two small plugs set into the bottom of each one, and these plugs fit into individual round sockets set into the track surface. In other words, the track curb receptacles are a series of individual metal sockets, while the drain is a continuous metal slot set flush with the surface.
David Katz has worked with the Millrose Games and other big-time track events for years, and is RRTC’s most track-knowledgeable person. Here he is in Atlanta in 1996, checking out a “waterfall” start.

A removable curb takes up a lot of space when it’s not installed. Here are two shots of the Atlanta Olympic track curbing. Note the pins on each segment of curbing. They fit into corresponding sockets in the track surface. Each segment of curbing is numbered so that the pins and holes fit exactly.

I thought this was about 'strange' track configurations. I've only encountered one odd track configuration - Bessemer, MI (far west end of MI's Upper Peninsula) has a rectangular track w/rounded edges. I couldn't believe it when I saw it and when I called the AD at the school to ask about it, she insisted it was oval. Hah! I took a Google Earth pic to keep for proof. I don't know how to load it up on this site.
Here's an image of track drain similar to the one Mark found.

More info on the ACO 3000 Drainage System - Slotted Drain is available at rennersports.com.

Thank you. -- Justin
I Google Earthed Bessemer, MI, and found this rounded quadrilateral track. It may not be the only one in Bessemer, but it seems likely. It Google measures to 400 meters.

I think square tracks aren't all that uncommon. Here's one in Fairmont, WV that I ran on in high school. A couple of those turns were pretty tough on the sprinters and hurdlers!
Yet another strange track that's part of a course measurer Dave Turner sent me.