This option allows the user to view and/or modify bridge width and distance data. Previous versions of HEC-RAS (versions 2.21 and earlier) allowed the user to enter a zero length between the cross sections inside of a bridge and the cross sections just outside of the bridge. This creates and unrealistic water surface profile in the vicinity of the bridge. Current versions require the user to maintain some distance between the outside cross sections and the bridge structure. This table was added to make the process of modifying old data sets less painful. When this option is selected, a window will appear as shown in Figure 5-76. As shown in Figure 5-76, the user is given the length between the cross sections that bound the bridge (Dist Avail), the distance between the upstream cross section and the bridge (Upstream Dist), the bridge width (Bridge Width), and the distance between the downstream cross section and the bridge (Downstream Dist). The user must ensure that the upstream and downstream distances are greater than zero. This will require entering an upstream distance, and then changing the bridge width to allow for a positive downstream distance.

Figure 5 76. Bridge Width and Distance Table