Incorporating Data-Driven Analysis in 

Intersection Analyses Through the Use of 

Intersection Control Evaluations:

A How-To Guide

Credit: Fotosearch.com
2

Introduction

Background

Traditionally, safety analysis to support roadway and intersection planning and design was largely based on qualitative 

or surrogate measures, or consisted only of a historical summary of crashes. Data-Driven Safety Analysis (DDSA) employs 

newer, evidence-based models that provide state and local agencies with the means to quantify safety impacts, similar 

to the way they do other impacts such as environmental effects, traffic operations, and pavement condition. DDSA 

provides reliable estimates of an existing or proposed roadway’s current and future safety performance and helps 

agencies make more informed decisions, better target investments, and reduce crashes occurring on their roadways. 

This guide describes how DDSA is being incorporated into intersection projects. 

When an intersection project is contemplated, studies are usually conducted to evaluate various alternatives. Typically, 

these studies involve intersection analyses that focus more on the capacity and operational aspects of the alternatives 

being considered, and less (if any) on analyzing the substantive safety performance of the proposed alternatives. To 

remedy this disconnect, a growing number of transportation agencies have begun implementing intersection control 

evaluation (ICE) policies and procedures. ICE is a data-driven, performance-based framework used to objectively screen 

alternatives and identify an optimal solution for an intersection. It involves quantitative and independent analyses of 

the safety, operations, right-of-way, cost, and other metrics important to transportation agencies. DDSA serves as the 

platform for comparing safety performance among intersection alternatives under the ICE process.

According to the Federal Highway Administration (FHWA) Primer on ICE, the ICE process is intended to occur as part of 

an established project development process, and apply to the construction of new intersections or when an agency is 

considering making any substantive changes to the traffic control or geometry of existing intersections. Substantive 

changes are usually considered for the following reasons:

• To implement safety improvements,

• To relieve congestion,

• To enhance multimodal facilities,

• To change the access to an adjacent parcel of land or development, and

• To implement broader corridor improvements, such as widening.
3

Benefits of Using DDSA on Intersection Projects

Incorporating DDSA into ICE helps to elevate safety performance as a criterion for choosing a preferred alternative, 

thereby enabling the development of safer roadways with each intersection project. From the transportation agency’s 

perspective, incorporating DDSA into the project development phases of every intersection project can foster steady 

progress toward achieving reductions in fatal and serious injury crashes, which form the basis of initiatives such as 

Vision Zero and Toward Zero Deaths.

This guide provides a high-level overview of how to conduct straightforward safety analyses using readily available 

tools and data as part of the ICE process. Information on the tools discussed in this guide and others can be found at 

Data-Driven Safety Analysis Resources - DDSA Toolbox. In addition, some state and local agencies have developed their 

own tools. Therefore, the analyst conducting the analysis should check with the agency about data availability and tool 

preferences.

Overview of the Intersection Control Evaluation Process

A typical ICE is conducted in two distinct stages. The first stage, scoping (or screening), is usually completed early in the 

project development process. During Stage 1, the analyst will inventory existing conditions by reviewing physical 

characteristics and geometrics, collecting traffic and safety data, characterizing the adjacent land uses, and assessing 

the site for walking and biking. Next, the analyst assesses the existing condition and an array of potential alternatives to 

determine if and to what extent each meets the project purpose and need, project goals, and site constraints. The 

purpose of Stage 1 is to establish a short list of viable design and control strategies for the intersection being evaluated. 

If there are multiple viable alternatives, these alternatives proceed to Stage 2 for further design development and indepth analysis to determine the preferred alternative. The results from Stage 2 can be used to conduct a benefit-cost 

analysis to support the selection of the preferred alternative.

Credit: Fotosearch.com
4

Figure 1 shows the integration of DDSA into the typical intersection analysis process by conducting an ICE, with the 

opportunities to integrate safety shown in bold lettering. 

Figure 1: Opportunities to Integrate Safety in the Typical Intersection Analysis Process Using ICE
5

Application of DDSA into Intersection Analyses

There are several opportunities to apply DDSA approaches and concepts into intersection analyses. These opportunities 

include obtaining and visualizing safety data, evaluating pedestrian and bicyclist accommodations, and conducting 

safety analyses on potential alternatives. This and other information about overcoming potential challenges in applying 

DDSA can be found in the companion document Incorporating Data-Driven Safety Analysis in Traffic Impact Analyses: A 

How-To-Guide. 

Example: Intersection Analysis with Data-Driven

Safety Analysis Integration

The following section provides an example of how DDSA can be integrated into an ICE. This example was based on an 

investigation due to ongoing safety concerns at the intersection. The example describes the typical process for an ICE, 

but places an emphasis on the crash data and safety analyses.

Project Overview

The intersection of Main Street and Park Avenue currently experiences heavy congestion and delay during both the 

AM and PM peak periods. A local property owner has also raised concerns regarding the number of crashes that have 

occurred at the intersection and has inquired about possible improvements. As a result, the road agency has determined 

that the intersection of Main Street and Park Avenue should undergo an intersection control evaluation. 

Credit: Fotosearch.com

PIC
6

Existing Conditions and Projected Growth

Main Street and Park Avenue are rural two-lane roadways located in the town of Springfield. The intersection currently 

operates as a two-way stop-controlled intersection, with Main Street operating under free-flow conditions. Park Avenue 

comprises the southern leg of the intersection, while an unpaved driveway acts as the northern leg of the intersection. 

Both the north and south approaches operate under stop-controlled conditions. Existing signage at the intersection 

includes:

• “Combination Curve/Intersection” (W1-10) signage with 30 MPH advisory speed plates on both the eastbound and 

westbound approaches,

• “Watch for Turning Vehicles” (W11-V3) signage along the eastbound approach, and 

• Double-facing Chevron (W1-8L/W1-8R) signs on the southwest quadrant for approaching eastbound and westbound 

vehicles.

The existing intersection geometry is shown in Figure 2.

Figure 2: Existing Conditions
7

Existing (2018) Intersection Volumes

The analyst collected existing condition turning movement counts for the intersection on a typical weekday in 

15-minute intervals. Turning movement counts were collected for both the AM (7:00 to 9:00 AM) and PM (4:00 to 6:00 

PM) peak periods. The existing AM and PM peak hour turning movement volumes are shown in Figure 3.

Figure 3: Existing Peak Hour Volumes

Pedestrian Volumes

Along with vehicular volumes, the analyst also collected pedestrian volumes for the intersection on a typical weekday 

in 15-minute intervals. The AM and PM peak period pedestrian counts are shown in Table 1.

Table 1: Peak Period Pedestrian Counts

Intersection Leg AM Peak Period PM Peak Period

North 0 2

South 0 0

East 1 0

West 0 1
8

Pedestrian and Bicycle Accommodations

While documenting the existing conditions, the analyst took an inventory of existing pedestrian and bicycle facilities 

during an on-site visit. The analyst documented the following observations:

• There are no pedestrian facilities present within the study area. Neither Main Street nor Park Avenue is equipped with 

sidewalks. Crosswalks are not provided at any of the four intersection approaches. 

• There were no ADA facilities, such as ramps and tactile domes, present at the intersection.

• A small number of cyclists were observed during the site visit. Due to the lack of separated bike facilities within the study 

area, all observed cyclists were seen sharing the road with motorists.

• There are no shared-use paths or trails present near the study intersection.

• No pedestrian generators are located immediately adjacent to the study intersection. However, the surrounding area is 

mostly residential.

Crash Data

The most recent five years of crash data were obtained and analyzed to evaluate trends by time of day, type of crash, and 

roadway conditions, and to develop collision diagrams and crash summaries. The collision diagrams helped determine 

crash patterns in relation to the subject intersection. The findings of the crash data analyses, illustrated in Figure 4 and 

Figure 5, included the following observations:

• A total of 11 crashes occurred at the intersection in the 5-year study period (2013-2017), and 5 of these 11 crashes resulted 

in injuries.. There were no crashes in 2017.

• Angle and fixed object crashes are the most prominent crash types, both accounting for approximately 36% of the total 

number of crashes each. Rear-end crashes are the third most prominent crashes (18% of crashes).

• 5 of the 11 crashes were a result of drivers “failing to maintain proper control.” This could be a result of geometry and 

roadway conditions promoting higher speeds.

• 3 of the 11 crashes occurred during dark lighting conditions. The lack of roadway lighting could be negatively impacting 

drivers’ ability to see and react to the intersection.

• 5 of the 11 crashes occurred under wet pavement conditions. The friction or pavement quality could be negatively 

impacting drivers’ ability to navigate the intersection.

Credit: Fotosearch.com
9

Figure 4: Crash Frequency by Type of Crash

Figure 5: Collision Diagram (2013-2017)
10

Projected Growth

Volume Forecasting

The build-out date is projected to be 2020; however, the analyst projected traffic growth to 2040, the proposed horizon 

date, by applying a historic growth rate to existing 2018 traffic volumes. Historic AADT data was collected from the 

state department of transportation’s (DOT) online database and used to determine historical growth trends along both 

Main Street and Park Avenue. Table 2 outlines the expected growth rates along the corridor segments approaching 

the existing intersection. A growth rate was not provided for the unpaved driveway representing the north leg of the 

intersection; therefore, an average of the three growth rates was used (1.763%). 

Table 2: Estimated Growth Rates

Approach Growth Rate

Main Street from Second Street to Park Avenue 2.39%

Main Street from Park Avenue to Oak Lane 0.99%

Park Avenue from Maple Avenue to Main Street 1.91%

The projected future volumes for the AM and PM peak period are shown in Figure 6.

Figure 6: Future (2040) Peak Hour Volumes
11

Pedestrian Volumes

The analyst also projected pedestrian volumes to the design year (2040) to evaluate future pedestrian needs for the 

project alternatives. While pedestrian volumes are estimated to be low and there is not existing pedestrian connectivity 

along either corridor, the analyst considered installing low-cost pedestrian improvements to accommodate existing 

and future pedestrian demand. 

Identify Alternatives

Preliminary Alternatives

Based on the results of the existing conditions evaluations, including the identification of safety issues, the analyst 

recommended the following alternatives:

• Alternative 1: Minor Road Stop with Turn Lane additions This alternative proposes to straighten the existing 

curvature of Main Street and relocate the intersection to be northeast of its current location to eliminate any impacts 

to the private property on the southwest corner. This option maintains a two‐way stop control at the study intersection 

but provides a modified lane geometry. Currently, three of the four approaches operate as shared lanes; however, the 

alternative proposes to modify two approaches to include separate turn lanes. 

• Alternative 2: Continuous T-Intersection This alternative proposes to modify the existing intersection to accommodate 

a continuous T-intersection design to favor the major movements of westbound to southbound and northbound to 

eastbound. The southbound approach (unpaved driveway) will be relocated to the west of the intersection.

• Alternative 3: Roundabout This alternative proposes to modify the existing intersection to accommodate a roundabout 

design. As the intersection operates with low volumes, only one concept was proposed for evaluation purposes, which 

includes one circulating lane, with one lane entry and one lane exit points on all four approaches of the intersection.

All three alternatives will include the addition of shoulders to provide pedestrians the ability to maintain separation 

from motor vehicles at the intersection.

Credit: Fotosearch.com
12

Stage 1 Scoping

Stage 1 analysis activities are designed to screen alternatives to determine if they are feasible as well as to calculate 

planning-level information on safety and operational performance.

Safety Analysis

The predictive analysis was conducted using the Safety Performance for Intersection Control Evaluation (SPICE) tool.1

For purposes of comparing relative safety performance, crash frequencies and severities were calculated for each of 

the three alternatives described previously for both the opening year (2020) and the design year (2040). To conduct the 

analysis, the analyst filled the parameters within SPICE with the available intersection information, such as existing and 

future AADT, intersection configuration, and historical crash data. 

The analyst established the basic analysis parameters and determined which control strategies to include in the SPICE 

analysis. The inputs selected for this analysis are shown in Figure 7. Opening year AADT’s were obtained from the state 

DOT’s traffic data database. The design year AADT’s were calculated using historical growth rates for Main Street and 

Park Avenue. Since the northern leg of the study intersection functions as a driveway, only 3-legs were used for the analysis.

Control Strategy Selection and Inputs

Specify the Facility Level Inputs and the Control Strategies to be included in the SPICE Analysis.

Parameter User Entry

Intersection Type At-Grade Intersections

Analysis Year Opening and Design Year

Opening Year 2020

Design Year 2040

Facility Type On Rural Two Lane Highway

Number of Legs 3-leg

1-Way/2-Way 2-way Intersecting 2-way

# of Major Street Lanes (both directions) 5 or fewer

Major Street Approach Speed Less than 55 mph

Opening Year - Major Road AADT 7,781

Opening Year - Minor Road AADT 3,363

Design Year - Major Road AADT 13,078

Design Year - Minor Road AADT 5,098

Figure 7: Control Strategy Selection Worksheet Inputs

1 American Association of State Highway and Transportation Officials. (2019). Tools. Retrieved from the Highway Safety Manual website: http://

www.highwaysafetymanual.org/Pages/Tools.aspx
13

The control strategies selected for the analysis were “Minor Road Stop”, “Continuous Green-T Intersection”, and “1-Lane 

Roundabout”, representing Alternatives 1, 2, and 3, respectively. The control strategy selections for this analysis are 

shown in Figure 8.

Control Strategy Include Base Intersection

Traffic Signal No --

Traffic Signal (Alternative Configuration) No --

Minor Road Stop Yes --

All Way Stop No --

1-Lane Roundabout Yes --

2-Lane Roundabout No --

Displaced Left Turn (DLT) No Traffic Signal

Median U-Turn (MUT) No Traffic Signal

Signalized Restricted Crossing U-Turn (RCUT) No Traffic Signal

Unsignalized Restricted Crossing U-Turn (RCUT) No Minor Road Stop

Continuous Green-T Intersection Yes Traffic Signal

Jughandle No Traffic Signal

Other 1 No Traffic Signal

Other 2 No Minor Road Stop

Figure 8: Control Strategy Selections

The analyst used the At-Grade Inputs worksheet to enter pertinent information relating to the at-grade study intersection 

for the SPICE analysis. The top section of the page, shown in Figure 9, allows users to override AADT information taken 

from the Control Strategy Selection worksheet, as well as provide information regarding the number of turn lanes for 

the stop-controlled and signalized control strategies. Although they are associated with the Highway Safety Manual 

(HSM) Part C Crash Modification Factors (CMF), turn lane inputs are required for planning-level analysis because they 

have a relatively high impact on crash prediction values. The turning lane inputs were updated to reflect the accurate 

number of turning lanes included in the minor road stop with turn lane additions (Alternative 1). 

Credit: Fotosearch.com
14

Input Input Type Minor Road Stop

Control Strategy

1-lane

Roundabout

Continuous 

Green-T

Intersection

Opening Year Major Road AADT

Optional AADT 

Overrides

7781 7781 7781

Opening Year Minor Road AADT 3363 3363 3363

Design Year Major Road AADT 13078 13078 13078

Design Year Minor Road AADT 5098 5098 5098

Number of Approaches with Left-Turn 

Lanes

Additional

Required Control 

Strategy Inputs

Number of Approaches with Right-Turn 

Lanes

Number of Uncontrolled Approaches with 

Left-Turn Lanes 2

Number of Uncontrolled Approaches with 

Right-Turn Lanes 1

Figure 9: At-Grade Intersection Inputs

The bottom section of the At-Grade Inputs worksheet allowed the analyst to override the default CMF-related inputs 

from Part C of the HSM. Since this is a planning-level analysis, the analyst left most of the inputs as the default value. 

The only inputs that were modified were the inscribed circle diameter and the volume entering the roundabout from 

the fourth leg, which represents the driveway on the northern end of the intersection. Once this step was completed, 

the analyst calculated the results of the analysis on the Results worksheet, shown in Figure 10

Credit: Fotosearch.com
15

Results

Summary of crash prediction results for each alternative

Project Information

Project Name: Main Street Intersection Control Evaluation (ICE) Intersection Type At-Grade Intersections

Intersection: Main Street & Park Avenue Opening Year 2020

Agency: State Department of Transportation Design Year 2040

Project Reference: XX-####-XXXX Facility Type On Rural Two Lane Highway

City: Springfield Number of Legs 3-leg

State: XXXX 1-Way/2-Way 2-way Intersecting 2-way

Date: 12/1/2018 # of Major Street Lanes 5 or fewer

Analyst: John Smith Major Street Approach 

Speed Less than 55 mph

Crash Prediction Summary

Control Strategy Crash 

Type Opening Year Design Year Total Project Life Cycle AADT Within Prediction Range?

1-lane Roundabout

Total 0.62 0.85 15.53

Fatal & Yes

Injury 0.14 0.23 3.84

Minor Road Stop

Total 1.24 2.28 36.75

Fatal & No

Injury 0.51 0.95 15.25

Continuous 

Green-T Intersection

Total 2.00 2.91 51.68

Fatal & N/A

Injury 0.66 0.96 17.07

Figure 10: Results Worksheet

The bottom section of the worksheet provides a crash prediction summary for each control strategy selected for this 

analysis. The summary includes the predicted total and fatal-injury crash frequencies for the opening year, design 

year, and the total project life cycle. For example, based on the results shown in Figure 10, the 1-lane roundabout is 

anticipated to have 0.62 total and 0.14 fatal-injury crashes during the opening year (2020), 0.85 total and 0.23 fatal-injury 

crashes during the design year (2040), and 15.53 total and 3.84 fatal-injury crashes over the project’s lifecycle (2020-

2040). The results are summarized in Table 3.

Table 3: Life Cycle Crash Frequency Results (SPICE)

Alternative Total Project Life Cycle Crash Frequency

Future No-Build* 76.26 (44.61 – PDO; 31.65 – FI)

Minor Road Stop with Turn Lane additions (Alternative 1) 36.75 (21.50 – PDO; 15.25 – FI)

Continuous T-Intersection (Alternative 2) 51.68 (34.61 – PDO; 17.07 – FI)

Roundabout (Alternative 3) 15.53 (11.69 – PDO; 3.84 – FI)

*The crash frequency for the Future No-Build scenario was generated using the Minor Road Stop road strategy,

similar to Alternative 1, but the at-grade intersection inputs were modified to reflect the existing number of lanes.
16

Each of the proposed alternatives was compared to the Future No-Build scenario to determine total crash reductions. 

The equation below illustrates the calculation for determining total crash reduction percentages for each alternative 

and the results are shown in Table 4.

Table 4: Crash Reduction Results from SPICE

Alternative Total Project Life Cycle 

Crash Frequency Total Crash Reduction Total Crash Reduction(Percentage)

Future No-Build 76.26 (44.61 – PDO; 

31.65 – FI)

N/A 0%

Minor Road Stop with Turn Lane additions 

(Alternative 1)

36.75 (21.50 – PDO; 

15.25 – FI)

39.51 (23.11 – PDO;

16.40 – FI) 

51.8%

Continuous T-Intersection

(Alternative 2)

51.68 (34.61 – PDO; 

17.07 – FI)

24.58 (10.00 – PDO;

14.58 – FI) 

32.2%

Roundabout 

(Alternative 3)

15.53 (11.69 – PDO;

3.84 – FI)

60.73 (32.92 – PDO;

27.81 – FI)

79.6%

Based on the safety analysis, 51.8%, 32.2%, and 79.6% total crash reduction percentages are expected for Alternatives 

1, 2, and 3, respectively.

Operational Analysis

The analyst conducted a capacity analysis for the three alternatives using the Capacity Analysis for Planning of Junctions 

(CAP-X) tool,2

 as shown in Figure 11. The analyst used peak traffic volumes as well as details on lane configuration, 

pedestrian facilities, and bicyclist facilities to estimate the volume-to-capacity (V/C) ratio for each alternative. 

The first step of the CAP-X analysis involves entering the traffic volume information. In order to account for the different 

analysis periods (AM and PM peak) and geometric arrangements (4-legged for Alternatives 1 and 3 and 3-legged for 

Alternative 2), four separate runs of CAP-X are required. The volumes are consistent across the different analysis scenarios, 

except for the very low volumes related to the north leg, which would not exist if 3-legged, effectively eliminating 

those volumes for analysis purposes. Table 5 reflects the volumes used for the 2040 PM peak period for the 4-legged 

scenarios. Note that in addition to hourly flows for each movement by approach in vehicles per hour, CAP-X prompts 

for the percentage of heavy vehicles and percentage of volume growth. For these analyses, truck percentage was set 

at 2 percent, and since future traffic demand was accounted for separately, volume growth was set to zero. Additional 

parameters required for CAP-X input includes the factor to use for Truck to Passenger Car Equivalent (PCE), Multimodal 

Activity Level (pedestrians/bicycles from low to high), and Critical Lane Volume Sum Limit based on number of basic 

signal phases. For all these additional parameters, default suggested values were used.

2 American Association of State Highway and Transportation Officials. (2019). Tools. Retrieved from the Highway Safety Manual website: http://

www.highwaysafetymanual.org/Pages/Tools.aspx

Alternative 1 Total Crash Reduction Percentage = x 100% 36.75 - 76.26 ( 76.26 )

Total Crash Reduction Percentage = Alternative Crash Frequency - No Build Crash Frequency

No Build Crash Frequency ( )
17

Table 5: CAP-X Analysis Traffic Volume Demand Inputs for the 4-Legged Intersection Alternatives.

Approach 

Direction

U-Turn Volume 

(veh/hr)

Left Turn Volume (veh/hr)Thru Volume 

(veh/hr)

Right Turn Volume (veh/hr)Heavy Vehicles

(percent)

Volume 

Growth

(percent)

Eastbound 0 1 120 10 2.00 0.00

Westbound 0 306 355 4 2.00 0.00

Southbound 0 1 1 4 2.00 0.00

Northbound 0 22 3 142 2.00 0.00

Figure 11: CAP-X Volume Input for the 4-Legged Intersection Alternatives 

as depicted in the accessible version of the sample data is available in Table 5.

The analyst next accessed the Base and Alt Sel worksheet to enter the existing intersection configuration and select the 

alternatives to analyze. The analyst selected “Two Way Stop Control” and “1x1 Roundabout” in the 4-legged instance 

of the tool, and “Continues Green T” in the 3-legged instance of the tool. In both cases, the two-way stop-controlled 

intersection was selected as the existing intersection configuration. Figure 12 and Figure 13 show the inputs for the 

4-legged alternatives being analyzed by instance of the tool. 
18

Figure 12: CAP-X Base Conditions Analysis for the 4-Legged Intersection Alternatives
19

Figure 13: CAP-X Alternative Selection for the 4-Legged Intersection Alternatives

Next, the analyst reviewed the Alt Num Lanes worksheet to enter the number of lanes for each alternative. CAP-X 

provides default values for each alternative, and the analyst adjusted these values to represent the lane configuration 

for each of the three alternatives. Figure 14 shows the completed worksheet for the 4-legged intersection (Alternatives 

1 and 3). 

Rankings Inclusion Yes/No Comment

At-Grade Non-Roundabout Intersections? Yes

Traffic Signal No

Two-Way Stop Control Yes

All-Way Stop Control No

Continuous Green T No

Quadrant Roadway

S-W No

N-E No

S-E No

N-W No

Partial Displaced Left Turn No

Displaced Left Turn No

Signalized Restricted Crossing U-Turn No

Unsignalized Restricted Crossing U-Turn No

Median U-Turn No

Partial Median U-Turn No

Bowtie No

Split Intersection No

Grade Separated Intersections? No

Echelon

Center Turn Overpass

Roundabouts? Yes

50 ICD Miniroundabout No

75 ICD Miniroundaobut No

1x1 Yes

1x2 No

2x1 No

2x2 No

3x3 No

Grade Separated Interchanges? No

Diamond

Partial Cloverleaf A

Partial Cloverleaf B

Displaced Left Turn Interchange

Contraflow Left Interchange

Diverging Diamond Interchange

Single Point

Single Point with Roundabout
20

Figure 13: CAP-X Alternative Selection for the 4-Legged Intersection Alternatives

Next, the analyst reviewed the Alt Num Lanes worksheet to enter the number of lanes for each alternative. CAP-X 

provides default values for each alternative, and the analyst adjusted these values to represent the lane configuration 

for each of the three alternatives. Figure 14 shows the completed worksheet for the 4-legged intersection (Alternatives 

1 and 3). 

Figure 14: CAP-X Alt Number of Lanes Input for the 4-Legged Intersection Alternatives

While the analyst does not expect high pedestrian or bicyclist demand in the future, understanding the safety effects 

of the different alternative designs is important when selecting the preferred alternative. CAP-X allowed the analyst to 

enter basic details about the lane crossings (Figure 15) and bicycle facilities (Figure 16). The tool uses these basic inputs 

to provide qualitative assessments of the pedestrian and bicyclist accommodations. 
21

Figure 15: CAP-X Inputs for the Multimodal Intersection Configuration for Pedestrian Crossing for the

4-Legged Intersection Alternatives

Figure 16: CAP-X Inputs for the Multimodal Intersection Configuration for Bicycle Segments for the

4-Legged Intersection Alternatives

Pedestrian Crossing Configurations for Non-roundabout Intersections

TYPE OF INTERSECTION Sheet # Of

 X-ings

Crossing #1 Crossing #2 Crossing #3 Crossing #4

# Lanes Veh Speed # Lanes Veh Speed # Lanes Veh Speed # Lanes Veh Speed

Two-Way Stop Control E-W 4 3+ Lanes >30mph 3+ Lanes Stop / Signal 3+ Lanes >30mph 1 Lane Stop / Signal

 Pedestrian Crossing Configurations for Separated Intersections

TYPE OF INTERSECTION Sheet # Of

 X-ings

Crossing #1 Crossing #2 Crossing #3 Crossing #4

# Lanes Veh Speed # Lanes Veh Speed # Lanes Veh Speed # Lanes Veh Speed

Pedestrian Crossing Configurations for Roundabouts

TYPE OF ROUNDABOUT Sheet # Of

 X-ings

Crossing #1 Crossing #2 Crossing #3 Crossing #4

# Lanes Veh Speed # Lanes Veh Speed # Lanes Veh Speed # Lanes Veh Speed

Single Lane Roundabout 1 X 1 4 2 Lanes <20mph 2 Lanes <20mph 2 Lanes <20mph 2 Lanes <20mph

Bicycle Segment Configurations for Non-roundabout Intersections

TYPE OF 

INTERSECTION Sheet # OfSeg.

Segment #1 Segment #2 Segment #3 Segment #4

Bike Lane Veh Speed Bike Lane Veh Speed Bike Lane Veh Speed Bike Lane Veh Speed

Two-Way Stop 

Control E-W 4 Shared with Vehicles >30mph Shared with Vehicles >30mph Shared with Vehicles >30mph Shared with Vehicles <20mph

Bicycle Segment Configurations for Separated Intersections

TYPE OF 

INTERSECTION Sheet # OfSeg.

Segment #1 Segment #2 Segment #3 Segment #4

Bike Lane Veh Speed Bike Lane Veh Speed Bike Lane Veh Speed Bike Lane Veh Speed

Bicycle Segment Configurations for Roundabouts

TYPE OF 

ROUNDABOUT Sheet # Of Seg.

Segment #1 Segment #2 Segment #3 Segment #4

Bike Lane Veh Speed Bike Lane Veh Speed Bike Lane Veh Speed Bike Lane Veh Speed

Single Lane 

Roundabout 1 X 1 4 Shared with Vehicles <20mph Shared with Vehicles <20mph Shared with Vehicles <20mph Shared with Vehicles <20mph
22

At this point, the analyst had entered all of the details needed to use the tool. The Summary Results worksheet provides 

an overview of the analysis results. The alternatives are ranked by their V/C ratio, and an assessment of both pedestrian 

and bicycle accommodations is presented. Figure 17 shows the output from CAP-X for the 4-legged intersection 

alternatives, and Table 6 shows the combined results for all three alternatives. 

Figure 17: CAP-X Summary Results for the 4-Legged Intersection Alternatives (PM Peak)
23

Table 6: Summary of CAP-X Results

Alternative Period V/C Ratio Pedestrian

Accommodations

Bicycle

Accommodations

Future No-Build 2040 AM Peak 0.48 Fair Fair

Future No-Build 2040 PM Peak 0.21 Fair Fair

Curve Realignment (Alt 1) 2040 AM Peak 0.48 Fair Fair

Curve Realignment (Alt 1) 2040 PM Peak 0.21 Fair Fair

Continuous T-Intersection (Alt 2) 2040 AM Peak 0.34 Poor Fair

Continuous T-Intersection (Alt 2) 2040 PM Peak 0.29 Poor Fair

Roundabout (Alt 3) 2040 AM Peak 0.45 Good Good

Roundabout (Alt 3) 2040 PM Peak 0.51 Good Good

Results of the CAP-X analysis show that all three alternatives have a V/C ratio of less than 0.85 in both of the peak 

periods. A V/C ratio of less than 0.85 indicates that the intersection typically has sufficient capacity to support the 

expected traffic demand. The V/C ratios range from 0.21 (Future No-Build and Alternative 1 during the 2040 AM peak) 

to 0.51 (Alternative 3 during the 2040 PM peak). 

Stage 2 Alternative Selection

Results of the CAP-X analysis (Table 6) show that all three of the alternatives will provide sufficient capacity for the 

expected demand. As such, the analyst decided that selecting the preferred alternative should be based on the 

expected safety benefits estimated by the SPICE tool (Table 5), and recommended that the roundabout (Alternative 

3) should be the preferred alternative. Given this recommendation, a more detailed Stage 2 analysis to compare the 

other alternatives may not be necessary. To further confirm the recommendation, the analyst conducted a benefit-cost 

analysis to determine if the safety benefits of the preferred alternative are expected to outweigh the alternative’s cost.

Benefit-Cost Analysis

To begin the benefit-cost analysis, the analyst developed a severity-weighted crash cost for fatal and injury crashes 

using three years of crash data and the costs shown in Table 7.

3

 The severity-weighted crash cost was calculated to be 

$446,212 (2016 dollars). The crash cost used for property damage only crashes was $11,900 (2016 dollars).

Table 7: Comprehensive Crash-Level Costs

Severity Comprehensive Crash-Level Cost

(2016 dollars)

K $11,295,400

A $655,000

B $198,500

C $125,600

O $11,900

The analyst estimated the present value of the cost savings due to the reduction in crashes  for the roundabout 

(Alternative 3) to be $7,454,973. With an estimated cost of $3,467,500, this project is expected to have a benefit-cost 

ratio of 2:1. 

3 Harmon, T., Bahar, G., & Gross, F. (2018). Crash Costs for Highway Safety Analysis (Final Report No. FHWA-SA-17-071). Washington, DC. Retrieved 

from https://safety.fhwa.dot.gov/hsip/docs/fhwasa17071.pdf
24

Preferred Alternative

Given the results of the benefit-cost analysis, the analyst recommended moving forward with implementing the 

roundabout (Alternative 3). The roundabout is superior to the other alternatives based on the reduction in fatalities 

and serious injuries. All three alternatives are comparable from an operational perspective. Selecting the alternative 

with the greatest safety improvement allows the analyst to be consistent with FHWA’s vision of zero deaths and serious 

injuries on the Nation’s roadways.

Key Findings

This analysis addressed the traffic-related impacts associated with the reconfiguration of the intersection between Main 

Street and Park Avenue. The following conclusions are based on the conducted typical capacity and safety analyses:

• The existing intersection has had 11 crashes over the most recent five years (2013 – 2017), with angle and fixed object 

crashes (36%) being the most common crash types. Nearly half of the crashes are a result of drivers “failing to maintain 

proper control.” The preferred solution, the roundabout, requires drivers to decrease their speed during the approach 

to the intersection. This decrease in speed is anticipated to reduce crashes related to drivers failing to maintain proper 

control and reduce the number of crashes at the intersection.

• Further, roundabouts greatly reduce the possibility of angle and head-on crashes. Both of these crash types are often 

severe, and angle crashes were observed frequently at this location.

• While estimates show little pedestrian demand in future years, all alternatives would include shoulder accommodations 

as a low-cost approach to improve pedestrian safety. The roundabout alternative is described as a more favorable 

option for pedestrians and bicycles in terms of vehicle speeds and crossing or segment characteristics.

• The roundabout (Alternative 3) is expected to make the greatest safety improvement, and the benefits are also expected 

to outweigh the costs. As such, this alternative has been selected as the preferred alternative. The design includes one 

circulating lane with one lane entry and one lane exit point on all four approaches of the intersection.

Conclusion

An analyst can integrate DDSA into an ICE with a few basic steps. This guide presented an overview of ICE and an example 

to compare intersection designs and address safety concerns. In this example, a roundabout was recommended as 

the preferred alternative. The analysis shows that the roundabout will provide a greater reduction in fatal and injury 

crashes while having similar operational characteristics as the other alternatives. The benefit-cost analysis found that 

the benefits exceed the costs for the recommended alternative, demonstrating that it is a sound safety investment that 

is one step closer to realizing the goal of zero deaths and serious injuries on the Nation’s roadways.

 FHWA-SA-20-004

Credit: Fotosearch.com