Background -

TxDOT has two types of SSTs available – segment and intersection. The segment SST applies to two-lane rural roadways and multi-lane rural roadways, whereas the intersection scoring tool applies to urban and suburban areas. The main purpose of the SST is to assist in making safety-driven decisions in the project design process to optimize safety before the project is constructed. The SSTs provide key information on the safety effects of several design elements and help to optimize safety before a project is constructed. It is not to achieve a certain score but rather to assist designers in making safety‐driven decisions to enhance the safety of the roadway. The intent of tools is to get the highest score for a particular project, given the constraints. These tools make use of several SPFs and CMFs. The tools can be used for all phases of project development. However, using it during the initial scoping stages is the most valuable. Scores from the initial scoping phase and at the final PS&E are required for reporting purposes. Safety scorings are required for Rural PM, 2R, 3R, and 4R projects. These project types are defined in TxDOT’s RDM.

Objective -

The basic design approach of tools is to assign design elements to categories, define standard and optimal values for each component, calculate individual element scores, and ultimately combine scores from each category to determine the total score. It provides a platform to compare two different design alternatives to Standard and Optimal Design by defining the maximum practical value for each design parameter to get the optimal score from a safety perspective. An optimal score of 100 refers to the maximum score from a safety perspective. The tool increase awareness of how design changes can affect safety. However, the tool is not intended for a final decision-making tool, not a requirement for project approval, not a substitute for engineering judgement, and also not intended to compare Districts.

Tool Description -

Within the rural roadway safety tool, roadway elements are classified into the following categories – geometric, traffic, and roadside. Geometric and roadside elements are weighted more heavily compared to traffic elements. The tool scores the project at the segment level with a maximum mile length. The tool is calibrated to a maximum of 15 miles, so more than one sheet has to be used to accommodate the total length of more than 15 miles. A merger tool combines the scores from both/multiple sheets and provides the weighted average. Similarly, the urban intersection tool incorporates geometric, traffic control, pedestrian, and bicycle elements in the tool. All elements are equally weighted in the tool. The total intersection score includes scores from all individual elements. Intersection scores from multiple intersections are weighted by the number of predicted crashes to give a corridor score. All the elements in both the tools were researched and quantified before incorporating into the tool.

Resources -

All the scoring tools can be found on . The details of each two different tool type and an eligibility matrix to determine when a SST is applicable can be found in at the following links – and . Urban intersections tool requires crash data information from the TxDOT’s crash data source - . The necessary query instructions are available on . All other relevant information, like PowerPoint slides, webinar videos, and tool definitions, are available on the Safety Score Tools Homepage. At the time of this publication, safety scorings for an urban context is under development. Eventually, all the tools will be integrated into the same webbased platform.