23 Transportation Research Record: Journal of the Transportation Research Board, No. 2636, 2017, pp. 23–31. http://dx.doi.org/10.3141/2636-04 The Highway Safety Manual (HSM) lists four methods for determining the change in crash severity in order of reliability. The life-cycle benefit– cost analysis currently used by the Utah Department of Transportation is similar to the least reliable method. To provide a tool to perform the most reliable method defined by the HSM—the predictive method— this research developed a spreadsheet-based tool to allow department engineers to perform life-cycle benefit–cost analyses for the 11 roadway segment types included in the HSM. The tool can be used to analyze the cost-effectiveness of safety-related improvements identified by the Utah crash prediction model, which was previously developed to identify safety hot spots on the state highway system. The concept and the spreadsheet layout are presented by using the rural two-lane, two-way highway spreadsheet as an example. Then a case of a rural two-lane, two-way highway with two selected countermeasures is presented to demonstrate the use of this spreadsheet to compare their benefit–cost ratios. One important aspect associated with life-cycle benefit–cost analyses of safety-related improvements is the cost of implementing such improvements. Safety-related improvements are often included in larger construction contracts and such costs vary significantly, depend- ing on the way they are included in the larger contracts. Hence, construc- tion costs of safety-related improvements—such as initial cost, periodic rehabilitation cost, and annual maintenance costs—must be prepared outside this spreadsheet by the user. The Utah Department of Transportation (Utah DOT) has made safety on roadways one of its top priorities, which can be seen in their cam- paign “Zero Fatalities: A Goal We Can All Live with.” This campaign is “all about eliminating fatalities on [Utah] roadways” (1). One way that Utah DOT accomplishes this goal of zero fatalities is by performing safety-related improvements on roadway segments that have experienced higher numbers of crashes than expected. To determine which improvement will be the most effective, different analyses can be performed, depending on the need of the analysis. One of these analyses is a life-cycle benefit–cost analysis (LCBCA) of these safety-related improvements, which might have different service lives. The Highway Safety Manual (HSM) presents the preferred method for performing LCBCAs of safety-related improvements (2). Part of this analysis of safety-related improvements is to determine the change in the number of crashes. The HSM contains a process for determining the change in average crash severity known as the Part C Predictive Method, which is an 18-step method for predicting average crash frequencies. The predictive method includes numer- ous predictive models that use safety performance functions (SPFs), crash modification factors (CMFs), and other adjustment factors to predict the number of crashes that a roadway segment will experience based on its specific characteristics. SPFs are regression models that estimate the average crash frequency for a specific roadway type based on the annual average daily traffic (AADT), segment length, and regression constants that are determined on the basis of the crash severity being considered, along with the roadway type. A CMF is an index of how much crash experience is expected to change following a modification in design or traffic control. A CMF is a ratio between the number of crashes per unit of time expected after a modification or measure is implemented and the number of crashes per unit of time estimated if the change does not take place (2). The HSM outlines four methods for determining the change in crashes in order of reliability. The most reliable method is the Part C Predictive Method, and the least reliable method simply uses observed crash data and applies a CMF without considering SPFs. Utah DOT has historically used the least reliable method to deter- mine the change in average crash severity when LCBCAs of safety- related improvements are performed. This research created a tool with which Utah DOT engineers can use the predictive method as part of the LCBCAs of safety-related improvements to improve the ability to perform consistent analyses. PURPOSE AND SCOPE The purpose of this research is to create an Excel-based spreadsheet program that performs LCBCA for safety-related improvements using the method ranked most reliable in the HSM. It uses the Part C Predictive Method to determine the reduction in crash severity and the life-cycle, present-value analysis method presented in Volume 1 of the HSM (2). The Part C Predictive Method does not have informa- tion for every type of roadway. The scope of this research includes 11 roadway types: 1. Rural two-lane, two-way (TLTW) highways; 2. Undivided rural multilane highways; 3. Divided rural multilane highways; 4. Two-lane undivided suburban and urban arterials; Implementing Highway Safety Manual Life-Cycle Benefit–Cost Analysis of Safety Improvements Jordan B. Frustaci, Mitsuru Saito, and Grant G. Schultz J. B. Frustaci, Kimley-Horn and Associates, Inc., 1920 Wekiva Way, Suite 200, West Palm Beach, FL 33411. M. Saito and G. G. Schultz, Department of Civil and Environmental Engineering, Ira A. Fulton College of Engineering and Technology, Brigham Young University, 368 Clyde Building, Provo, UT 84602. Corresponding author: M. Saito, msaito@byu.edu.