systems, that meet the restrictions noted earlier in this section.

In [@GreulichS08a] it was shown that the maximum current in particle conserving driven lattice gases with randomly distributed defects but low defect density depends approximately only on the size of the longest bottleneck *(Single Bottleneck Approximation, SBA)*. This fact, together with the observations made in [@pff_1def], motivates the generalization of the transport capacity to driven lattice gases (including TASEP/LK) with many defects but low defect density, introducing an approximation similiar to SBA. We call it the *locally independent bottleneck approximation (LIBA)*: The transport capacity at a site $x$, $J^*(x)$, is approximately equal to the maximum current that can be achieved by tuning the boundary rates in the corresponding system containing [*only one*]{} bottleneck at this site [^5]. Thus $J^*(x)$ can be obtained by refering to a single-bottleneck system where all other defects (except the bottleneck at site $x$) have been removed.

In systems without LK the current is spatially constant and cannot exceed the minimum of $J^*(x)$ which corresponds to the transport capacity of the longest bottleneck, since in single bottleneck systems the maximum current is equal to the local transport capacity $J^*(x)$ and decreases with $l$ [@GreulichS08; @prot_prod_zia2; @bn_quasiexact]. 