Across the median crashes are high severity, often fatal crashes occurring when errant vehicles cross the median and enter the opposing lanes of travel. Guidelines for the installation of median barriers presented in the AASHTO Roadside Design Guide were developed in the 1960’s. A study of across the median crashes on Washington’s multilane, divided state highways, with full access control, was conducted to evaluate median barrier guidelines and identify specific highway sections where installation of a barrier is desirable. A benefit/cost analysis was conducted to evaluate the cost effectiveness of median barrier installation. The analysis was used to develop revised guidelines for median barrier installation. In addition, the benefit/cost methodology provides a means for ranking median barrier needs based on past crash history. This ranking will allow these improvements to compete for safety improvement funds.