In an effort to address this particularly frequent and severe crash type, the Alabama Department of

Transportation (ALDOT) implemented a policy in February 2006 to widen pavements and install

milled-in rumble strips when rural two-lane highways with less than 28 ft of pavement width are

resurfaced. On the vast majority of these roadways, little or no hard-surfaced shoulder had

previously existed. The policy determined that upon resurfacing, shoulders were to be

strengthened, 2 ft of full-depth pavement added on each side of the roadway, and in some cases,

rumble strips or stripes were scored into the pavement within the 2 ft shoulder. In practice, this

policy was extended to four-lane divided rural roads and paved shoulders widths were in a range

from 2 to 4 ft.

The practice of pavement widening, or shoulder wedging, to provide an additional recovery

area for errant vehicles leaving the travel lane but prior to leaving the pavement surface is

becoming increasingly common in many states. Although this had previously been done in

isolated cases in Alabama, this new policy represents a major effort to reduce roadway departure

crashes on rural roadways over the next several years.

Due to the level of investment associated with this policy, and its intended safety benefits,

a study to quantify the potential benefits is worthy of consideration, and its findings could possibly

be used to further support this initiative. The Empirical Bayes (EB) method, as outlined in the

Highway Safety Manual, the equivalent property damage only (EPDO) analysis, and the benefit-cost analysis are proposed to address safety effectiveness of the countermeasures implemented in Alabama. The objectives of this study are as follows:

1. Document the state of the practice and results of prior research;

2. Estimate reduction in run-off-road (ROR) crashes, by severity, based on the data, applying

both EB and EPDO methods

3. Develop crash modification factors for the following five treatments:

- Paving 2 to 4 ft of unpaved shoulders on two-lane rural roads;

- Combined effect of paving 2 to 4 ft of unpaved shoulder and adding rumble strips

on two-lane rural roads;

- Combined effect of paving 2 to 4 ft of unpaved shoulder and adding rumble stripes

on two-lane rural roads;

- Paving 2 to 4 ft of unpaved shoulders on four-lane divided rural roads;

- Combined effect of paving 2 to 4 ft of unpaved shoulder and adding rumble strips

on four-lane divided rural roads;

4. Quantify the benefits and costs of the ALDOT policy;

5. Make recommendations for future application. This report is not intended for construction, bidding, or permit purposes.