David,
It's difficult to determine if that was the architect's original intent, or, if it's a product of shoddy workmanship, Father Time, improper topdressing and maintainance, erosion, insufficient funds, drainage, nature, or a combination of some or all of the above.
If this subject has become an issue, I'd suggest finding out what CBM, SR, CB, DR, AM, AWT, GT, WF and others thought about the subject of designing, constructing and maintaining tees.
On the surface, it seems that they would be concerned with all of the issues I raised above, and that tees would have been built "properly" if the funds were available.