CAP-X and SPICE

The Federal Highway Administration (FHWA) has developed two tools that provide a high-level evaluation of the capacity and safety at an intersection. The Capacity Analysis for Planning of Junctions (CAP-X) tool is meant to evaluate different intersection types to estimate the volume / capacity (v/c) ratios based on different configurations. The Safety Performance for Intersection Control Evaluation (SPICE) tool was similarly developed to estimate the safety benefits or impacts of different intersection configurations. These tools are specifically designed for use as screening tools in the Intersection Control Evaluation (ICE) process. However, they can also be used for other studies when evaluating different intersection types. Both the CAP-X and SPICE tools are Microsoft Excel based and can be used with some basic information about the intersection. 

CAP-X

The CAP-X tool uses peak intersection volumes and the number of lanes to estimate the existing v/c ratio of the study intersection. The tool can analyze 17 different types of intersections, and provide a comparative v/c ratio for each type based on the existing volumes. This information can be used by the analyst to screen potential intersection alternatives by determining which intersection types will have the available capacity to meet the existing traffic demand.  

Information Needed for CAP-X Analysis:

• Existing turning movement volumes

• Existing intersection configuration including number of lanes

CAP-X information & tools to download can be found here. 

SPICE

The SPICE tool uses the Highway Safety Manual predictive analysis methodology to provide a comparison of safety impacts of alternative intersection control configurations. The SPICE tool provides an objective, quantifiable way to calculate the anticipated safety benefits or impacts of intersection configurations. This information can be used by the analyst to screen potential intersection alternatives by determining which intersection types will reduce crashes and provide an overall safety benefit.

Information Needed for SPICE Analysis:

• 5-Year Crash History

• Existing intersection configuration including number of lanes

• Existing and future design year average annual daily traffic (AADT) volumes for each leg of the intersection

Local calibration numbers for Utah intersections can found in the Historical and Predictive Analysis article.

SPICE information & tools to download can be found here.

Other Resources

https://highways.dot.gov/safety/intersection-safety/ice