I know that a lot of people prefer loop trails to out and back trails. So I wanted to point out that there are now 2 loops on the Trinity Trails near downtown Fort Worth. The 2 loops actually form a figure 8 for a 4.5 mile total length. The lower loop is contained withing Trinity Park and the upper loop extends from the North end of Trinity Park to the Panther Island Pavilion area. The middle of the 'figure 8' is the Phyllis Tilley Memorial Bridge.
Note: 1.1 miles of the lower left of the trail (in Trinity Park) is crushed gravel trail only. The rest is paved and mostly dual trail.
Here's a view of the 2 loops (click on the map to be taken to an interactive Google Map):