Correct me if I'm wrong, but the track you have comes in one meter lengths - Shinohara most likely.
If you flip it over, you will notice that the tie strip is missing the little links under both rails where the larger gaps are - there are actually eight separate sections of linked tie strip under the single length of rails. (Atlas has four 9 inch sections of tie strip under 36 inch rails.)
Part of the reason is that Japanese prototype jointed rail has two closely-spaced ties under the joint bars, which are square and not staggered. By leaving the gaps you note, it is possible to slide the tie strip to open a one-joint-tie gap every 20 scale meters, which is where the prototype joints would fall. To get the same effect with Atlas flex, I have to do some creative cutting and sliding, and lose a couple of ties from each length of flex track.
Your flex was set up for the convenience of Japanese (and British) modelers. By sliding and twisting a few ties, you can close the gaps, simultaneously losing the 'too perfect' alignment of the ties.
Chuck (Modeling Central Japan in September, 1964 - on Atlas concrete-tie flex)
I don't have a piece of flex track at hand as I write this, nor do I know what brand you bought, but most lines of flex track have some "relief points" I guess we could call them, where there is a slight gap of this sort. One possible reason for them is so that when the track is bent the ties have a place they can scrooch to (as you can see I am using highly technical terms here). So it looks like a gap when tangent but would tend to fill in if bent tight enough.
Also don't forget that in actual practice when you use flex track, you are often cutting it to length rather than always using a pure 3' piece. So another possible reason for those intermediate gaps is to provide a place where perhaps the ties can be slid down to to create needed gaps for rail joiners etc.
These are just guesses by me. My experience is that once the track is laid and ballasted and weathered a bit you do not notice those slight variations. If it really bugs you you can remove some ties at either side of the gap and redistribute them under the rails at slightly compromise distances to minimize the size or regularity of the gap. You do the same thing where rails meet, under or around the rail joiners, to avoid having an even bigger gap. These ties are just dummies in a sense -- not attached to the rails.
Dave Nelson
Hi folks. I'm building my fiest layout. I purchased some flextrack and noticed that every 4 7/8" there is a slightly wider space between the ties. Is this normal or did I get some junk? Also, disregard my previous post ( the empty one ). Hope I can lay track better than I can use a computer!