These relationships of congestion to layout geometry and density have been tested in two studies using computer-based traffic modeling applied to large subdivisions. A 1990 study compared the traffic performance in a 700-acre (2.8-km2) development that was laid out using two approaches, one with a hierarchical street layout that included cul-de-sac streets and the other a Traditional Neighborhood Design street layout. The study concluded that the non-hierarchical, traditional layout generally shows lower peak speed and shorter, more frequent intersection delays than the hierarchical pattern. The traditional pattern is not as friendly as the hierarchical to long trips but friendlier to short trips. Local trips in it are shorter in distance but about equivalent in time with the hierarchical layout.