Strongly uniform extensions of dual 2-designs

A strongly $\alpha$-uniform partial space of lines of order $(s,t)$ is called an $\alpha$-partial geometry. If $\alpha=t+1$, then the geometry is called a dual 2-design. Locally triangular and locally Grassman graphs correspond to triangular extensions of certain dual 2-designs, and the class of strongly uniform quasi-biplanes coincides with the class of strongly uniform extensions of dual 2-designs. We study strongly uniform extensions of dual 2-designs.