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Earlier this week I had the opportunity to drive through various construction sites that were retrofitting energy absorbing terminals (See attached pictures).   One question I had was about the slope just off of the gravel widening near the terminal.  In this case the slope is approximately 1.5:1 and the terminal platform is approximately 2' higher than the grass slope.  The grass slope is typically 4:1 or flatter.  Figure 5.1b, of the Roadside Design Guide would indicate that this is acceptable (see page 2).

Given the instability of a vehicle during impact with the terminal, should this slope be permitted at the terminal?

The attached figure contains current FHWA guidelines for grading around terminals. The green area must be 3:1 or flatter. Our research would suggest that the orange region could be as steep as 3:1, even though FHWA gives a more conservative recommendation. We do not believe that 1.5:1 is acceptable under any circumstance.