FHWA Safety Performance for Intersection Control Evaluation (SPICE) Tool Virginia Section ITE Annual Meeting Virginia Beach June 217 Pete Jenior Kittelson & Associates, Inc. 1
Intersection Control Evaluation (ICE) Background States with objective intersection control evaluation policies: California Indiana Minnesota Wisconsin Washington Under development: Pennsylvania Florida Georgia Nevada Texas Supported by FHWA s Every Day Counts Initiative Shortening project delivery Enhancing roadway safety Protecting the environment DOTs should consider and evaluate [roundabouts, diverging diamond interchanges (DDIs) and intersections with displaced left-turns or variations on U-turns] early in the project scoping, planning and decision-making stages, as they may serve as more efficient, economical and safer solutions than traditional designs. -FHWA http://www.fhwa.dot.gov/everydaycounts/edctwo/21 2/geometrics.cfm 2
Intersection Control Evaluations What is an Intersection? The connection or crossing of two or more roadway facilities Typical focus: At-grade forms We have been challenged implementing roundabouts over the last 2 years We now have more innovative forms to consider Mostly treatments of left-turning vehicles Intersection control evaluations apply to grade separated facilities Objective look at interchange form and function Focus is most often upon the ramp terminal intersection control of diamonds Stop Yield (roundabout) Signalized conventional Signalized crossover (diverging diamond) Signalized single intersection (single-point diamond) 3
Many Alternatives, Many Choices Perform engineering studies Use appropriate analysis tools Don t disregard viable alternatives just because they are new or different Source: NCHRP Report 825 4
VDOT ICE Efforts VDOT Central Office developing screening tool Modification of FHWA CAP-X spreadsheet Critical lane volume analysis of alternative intersections Conflict point analysis Additional tools/guidance/policy likely 5
Intersection Control Evaluation General Steps Consider project context Initial screening evaluation Performance-based decisions Operations Safety (the hard part!) Multimodal Quality Of Service Project Phasing Life Cycle Cost 6
Vision and Need for the SPICE Tool Safety comparisons of intersections becoming more common ICE, increased use of HSM in general, etc. Challenges with safety analysis in early project stages Which CMF is right? What should the CMF be applied to(existing, another alt, etc.)? I heard there s a new SPF for - what is it? Simple tool needed for intersection safety comparisons only Same level of effort as CAP-X Doesn t need to do road segment safety Doesn t need to do life cycle cost Doesn t need to do delay, maintenance, emissions, etc. Established tools for these already 7
SPICE Tool Key Attributes Performs predictive safety analysis of at-grade intersection forms/control types and ramp terminal intersections Implements the methodologies of the Highway Safety Manual (HSM) Developed with goal to be user-friendly Only requires data inputs readily available to the analyst Option to conduct planning level analysis Macro-powered Excel file Allows simultaneous evaluation of multiple forms and control types Tool will work for vast majority of intersections 8
Predictive Safety Analysis of an Alternative 9
Intersection Types At-Grade Intersections Traffic Signal (conventional) Minor-road Stop Control All-Way Stop Roundabout (yield control) Displaced Left Turn (DLT) Median U-Turn Signalized Restricted Crossing U-Turn (RCUT), also known Superstreet Unsignalized Restricted Crossing U-Turn (RCUT), also known as J-Turn Continuous Green-T Intersection Jughandles Ramp Terminal Intersections of Diamond Interchanges Traffic Signal (conventional) Minor-road (i.e. ramp) Stop Control Roundabout (yield control) Single-point Traffic Signal (of a signal point diamond) Crossover Traffic Signal (of a diverging diamond) 1
At-Grade Intersections in SPICE Tool Control Facility Type # legs 1 way/ 2 way # of lanes on arterial Traffic Signal On Rural Two Lane Highway 3 leg - - 4 leg - - On Rural Multilane Highway 3 leg - - 4 leg - - On Urban and Suburban Arterial 3 leg 2x2 5 or fewer 4 leg 2x2 5 or fewer 3 leg 2x2 6 or more 4 leg 2x2 6 or more 3 leg 1x2-4 leg 1x2-3 leg 1x1-4 leg 1x1 - On High Speed (5+ MPH) Urban and Suburban Arterial 3 leg - - 4 leg - - Minor Road Stop On Rural Two Lane Highway 3 leg - - 4 leg - - On Rural Multilane Highway 3 leg - - 4 leg - - On Urban and Suburban Arterial 3 leg 2x2 5 or fewer 4 leg 2x2 5 or fewer 3 leg 2x2 6 or more 4 leg 2x2 6 or more 3 leg 1x2-4 leg 1x2-3 leg 1x1-4 leg 1x1 - On High Speed (5+ MPH) Urban and Suburban Arterial 3 leg - - 4 leg - - All-Way Stop On Rural Two Lane Highway 4 leg - - On Urban and Suburban Arterial 3 leg - - On Urban and Suburban Arterial 4 leg - - 1-lane Roundabout - 3 leg - - - 4 leg - - 2-lane Roundabout - 3 leg - - - 4 leg - - Displaced Left Turn (DLT) - - - Median U-Turn (MUT) - - - Signalized Restricted Crossing U-Turn (RCUT), also known Superstreet - - - Unsignalized Restricted Crossing U-Turn (RCUT), also known as J-Turn - - - Continuous Green-T Intersection - - - Jughandles - - - 11
Ramp Terminal Intersections in SPICE Tool Control Conventional Traffic Signal Crossover Traffic Signal (of Diverging Diamond Interchange) Single-Point Diamond Traffic Signal Minor Road (ramp) Stop 1-lane Roundabout 2-lane Roundabout Ramp and Intersection Type Four-leg terminals with diagonal ramps (D4) All types All types Four-leg terminals with diagonal ramps (D4) 4 legs 4 legs 12
Alternative Intersections what are they? Median U-Turn (MUT) 13
Alternative Intersections what are they? Restricted Crossing U-Turn (RCUT) 14
Alternative Intersections what are they? Jughandle 15
Alternative Intersections what are they? Displaced Left Turn 16
Alternative Intersections what are they? Continuous Green T 17
Alternative Intersections what are they? Quadrant Roadway 18
Sources of Safety Information HSM 1 st Edition CMF Clearinghouse Alternative intersections NCHRP Project 17-58 6- and 8-lane urban and suburban arterial SPFs One-way urban and suburban arterial SPFs NCHRP Project 17-7 (ongoing) Roundabout SPFs NCHRP Project 17-68 (ongoing) 3-leg rural highway signal SPFs High-speed urban and suburban arterial SPFs All-way stop SPFs Single-point diamond SPFs 19
Examples of Scenarios Accommodated by SPICE Tool Primary Examples New intersection conventional signal or various alternative forms Ramp terminal intersection with conventional signal, crossover signal (i.e. DDI), or roundabout Secondary Examples TWSC being converted to signal or roundabout Signal being improved or converted to a roundabout 2
SPICE Introduction Introduction The Safety Performance for Intersection Control Evaluation (SPICE) Tool was developed to provide an easy-to-use tool that automates the predictive safety analysis of intersections. This tool will allow analysts conducting Intersection Control Evaluations (ICE) to be equipped with necessary safety information during the decision-making process, without having to research a myriad of crash modification factors (CMFs) and Safety Performance Functions (SPFs) in multiple sources. The SPICE tool will perform a comparative predictive safety analysis of different intersection control strategies. The results crash frequency and severity for each alternative will then enable safety performance of alternatives to be considered quantitatively like traffic operations, construction cost, maintenance cost, or other factors. Maintenance Version: SPICE Tool 1. Maintained By: TBD Contact Information: TBD Disclaimer Disclaimers may be added, if needed. Federal Highway Administration (FHWA) Safety Performance for Intersection Control Evaluation Tool Overview Worksheets Project Information: Provide general project information for reference purposes only. Alternative Selection: Specify the number of alternatives being considered and the intersection control of each alternative. Predictive Inputs: Provide inputs needed to compute and apply Part C CMFs. Calibration: Input optional override values for SPF calibration factors from locally-developed or updated information. Results: Summary of opening year and (if applicable) design year and total project life cycle crash frequency and crash severity. Additional Worksheets: Additional worksheets to support the underlying Macros. Not to be updated by users unless updating future tool versions. The SPICE Tool performs safety analysis of at-grade intersection forms/control types and ramp terminal intersections of diamond interchanges. This user-friendly tool requires only data inputs that are readily available to the analyst. In addition, the SPICE tool has an option to conduct planning level analysis, where the tool assumes default values for data inputs that are challenging to obtain in the early stages of a project and/or have a very minor impact on the results. The SPICE tool assumes that certain attributes of the intersection AADT, facility type, and number of legs are the same for all alternatives. If they are not, users will be required to use the tool twice to get results. The tool will not allow simultaneous evaluation of at-grade intersections and ramp terminal intersections. For projects where analysis of both intersections and interchanges is needed, users are required use the tool twice to get results. Input Legend Required data entry field Optional data entry field Planning-Level Default Input Data entry field not used 21
SPICE Basic Inputs and Control Strategy Selection 22
Optional Required SPICE At-Grade Intersection Inputs AADT Volumes for major/minor roads for the opening and design years Number of major approaches with left-turn or right-turn lanes Input Opening Year Major Road AADT 2 Opening Year Minor Road AADT 1 Design Year Major Road AADT 25 Design Year Minor Road AADT 15 Number of Major (Uncontrolled) Approaches with Left-Turn Lanes Number of Major (Uncontrolled) Approaches with Right-Turn Lanes Reset Planning Inputs to Defaults Base Conditions Optional AADT Overrides Additional Required Control Strategy Inputs Traffic Signal 2 1 25 15 Control Strategy Planning Level Defaults (Optional Overrides) Minor Road Stop 2 1 25 15 Pre-filled planning-level defaults Can be overridden by analyst Skew Angle Lighting Present # of Approaches Permissive LT Signal Phasing # of Approaches Perm/Prot LT Signal Phasing # of Approaches Protected LT Signal Phasing Number of Approaches with Right-Turn-on-Red Prohibited Red Light Cameras Present Number of Major Street Lanes (Including Turn Lanes) Number of Minor Street Lanes (Including Turn Lanes) # of Major St Approaches w/ Right-Turn Channelization Number of Approaches with U-Turn Prohibited Pedestrian Volume by Activity Level A yellow cell indicates the value may be used in the SPF computation N/A Yes No Low (2) Yes N/A N/A N/A N/A N/A N/A User Specified Sum of all daily pedestrian crossing volumes Max # of Lanes Crossed by Pedestrians Number of Bus Stops within 1' of Intersection Schools within 1' of intersection Number of Alcohol Sales Establishments within 1' of Intersection 2 5 No N/A N/A No 23
SPICE CMF Specification and Optional Local Calibration Crash Modification Factors (CMFs) used when safety performance functions (SPFs) are unavailable Control Displaced Left Turn (DLT) Median U-Turn (MUT) Signalized Restricted Crossing U-Turn (RCUT), also known Superstreet Unsignalized Restricted Crossing U-Turn (RCUT), also known as J-Turn Continuous Green-T Intersection Jughandles Crossover Traffic Signal (of Diverging Diamond Interchange) Local CMFs Optional - Override default CMFs with locallly-developed or new CMFs Type of Crashes Total Fatal-Injury Total Fatal-Injury Total Fatal-Injury Total Fatal-Injury Total Fatal-Injury Total Fatal-Injury Total Fatal-Injury Default CMF.88.88.85.7.85.78.65.46.96.85.74.74.67.59 Optional User Override Use Value.88.88.85.7.85.78.65.46.96.85.74.74.67.59 CMFs can be overridden with local values Local calibration factors can be applied when data is available 24
SPICE Crash Prediction Outputs Computes predicted crashes for all selected control strategy types Predicted crashes are broken into Total and Fatal & Injury groups Crash Prediction Summary Control Strategy Crash Type Opening Year Design Year Total Project Life Cycle Traffic Signal Minor Road Stop Displaced Left Turn (DLT) Median U-Turn (MUT) Signalized RCUT Unsignalized RCUT Jughandle Total 6.29 8.73 166.27 Fatal & Injury 2.55 3.57 67.72 Total 4.65 6.13 119.35 Fatal & Injury 2.23 3.1 57.94 Total 5.54 7.68 146.31 Fatal & Injury 2.24 3.14 59.59 Total 5.35 7.42 141.33 Fatal & Injury 1.78 2.5 47.4 Total 5.35 7.42 141.33 Fatal & Injury 1.99 2.79 52.82 Total 3.3 3.98 77.58 Fatal & Injury 1.2 1.38 26.65 Total 4.66 6.46 123.4 Fatal & Injury 1.89 2.64 5.11 25
Timeline and Questions SPICE tool will be available in early 218 26