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FHWA Home / Safety / Intersection / Presentation: Intersection Safety Implementation Plans

Presentation: Intersection Safety Implementation Plans

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Slide #1

Blueprints for Improving Intersection Safety


Slide #2

Overview and Purpose

Speaker's Notes

This presentation is intended for State and local safety engineers and professionals. The information presented here provides more information on intersection safety and the tools needed to develop and implement an Intersection Safety Implementation Plan (ISIP), regardless if your agency has an existing ISIP or is just interested in improving intersection safety.


Slide #3

Intersection Safety Problem

United States Fatalities by FHWA Focus Area: Average 2011-13. Pie chart shows percent fatality types from total fatalities on average 2011-13. Roadway departure only crashes made up 50%, intersection only 16%, ped/bicycle only 12%, crashes not involving focus area 12%, multiple focus areas 11%. A second pie chart breaks down multiple focus area crashes. Of that 11%: 5% intersections and ped/bicycles, 4.4% intersections and roadway departures, 1.3% roadway departures and ped/bicycles, 0.2% all focus areas.

Data for Intersection Focus Area from FHWA Safety Data Dashboard at: rspcb.safety.fhwa.dot.gov/Dashboard/Default.aspx

Speaker's Notes

The Federal Highway Administration (FHWA) has identified three focus areas as providing the greatest potential to reduce highway fatalities using infrastructure improvements–intersections, roadway departure, and pedestrian/bicyclists–because they account for about 90 percent of all fatalities. In 2014, intersection crashes resulted in 8,664 fatalities.

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Slide #4

Focused Approach to Safety


Slide #5

Intersection Safety Program

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Slide #6

Approaches to Safety Improvement

Approaches to Safety Improvement: Five overlaying circles represent the five approaches to safety improvement. Smallest circle is traditional approach. The next circle represents systemic approach.  The third approach is comprehensive approach. The fourth and fifth largest circles are policy and culture.

Speaker's Notes:

There are three approaches agencies can use to improving intersection safety. The hot-spot is a more traditional approach but is expensive and only addresses issues as they arise. The systemic approach addresses all locations, regardless of crash data. This requires less analysis but more funding. The comprehensive approach identifies locations with the greatest risks, rather than exact locations. Analysis can focus on crash types or facility types and similar characteristics. This allots the funding to priority intersections.

Policy and culture also influence safety improvements, although on a much broader perspective and higher level.

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Slide #7

Approach to Safety Improvement – Traditional

Traditional Approach (aka Hot Spot)

Speaker's Notes:

Traditional Approach: cost-effective but minimal impact

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Slide #8

Systemic Approach

Approach to Safety Improvement - Systemic

Speaker's Notes:

Systemic Approach:

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Slide #9

Traditional vs. Systemic

Traditional vs. Systemic approaches –  With the traditional approach, a three million dollar budget could be used to construct roundabouts at three intersections, at one million per intersection, and reduce 24 crashes per year, or 40 percent of total crashes. The same budget could be used systemically to make minor improvements at 500 intersections, at $6,000 per intersection, and reduce 75 crashes per year.

Speaker's Notes:

 

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Slide #10

Systemic Safety Project Selection Tool

Systemic Safety Project Selection Tool –The first step in project selection is to identify focus crash types and risk factors; the second, to screen and prioritize the candidate locations; the third, to select countermeasures; and the final step is to prioritize projects. Each step has an arrow leading down to the next step, and another leading back up to the previous step.

Speaker's Notes:

The FHWA Systemic Safety Project Tool presents step-by-step guidance on conducting a systemic safety analysis process for incorporating systemic safety planning into traditional safety management processes. The Systemic Tool provides a step-by-step process for conducting systemic safety analysis; considerations for determining a reasonable distribution between the implementation of hot-spot safety improvements and systemic safety improvements; and, a mechanism for quantifying the benefits of safety improvements implemented through a systemic approach. State and local transportation safety practitioners can use this tool to plan, implement, and evaluate systemic safety improvement programs and projects.

The systemic safety planning process consists of four steps that can be adapted based on the availability, quality, and quantity of data and technical resources. Similar to other common safety management processes, the steps include identifying the problem, screening and prioritizing candidate locations, selecting countermeasures, and prioritizing projects. It begins with analyzing and identifying focus crash types – those representing the greatest number of severe crashes – and potential risk factors. Then, the process moves to a micro-level assessment of locations across the network. This leads to selecting appropriate countermeasure and then prioritizing projects. This is an iterative process; and, as shown by the upwards arrows, some steps may be revisited for adjustments throughout the process.

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Slide #11

ISIP Development


Slide #12

ISIP Process

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Slide #13

ISIP Process

ISIP Process –  The first step in the ISIP process is to set a crash reduction goal. Then, expand current approach to achieve goal; identify intersection countermeasures; analyze data and identify a target intersection; develop a straw man outline; conduct a workshop to refine countermeasures and budget; develop a draft ISIP; present the draft to upper management; implement their suggestions; and finally, implement the plan, monitor its progress, and evaluate the results.

Speaker's Notes:

FHWA has developed a guide to developing an ISIP. The Intersection Safety Implementation Plan Process provides more detail on the 10-step process for developing an ISIP. To set a crash reduction goal, States should consult their Strategic Highway Safety Plan.


Slide #14

Reduction in Absolute Numbers

ISIP process step: Set Crash Reduction Goal

Example: Reduce fatalities by a total number, by a given date

Reduction in Rate

Example: Reduce fatality rate for each year of the last 5 years of data

Speaker's Notes:

SHSP goals tend to take two forms: crash frequency and crash rate.

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Slide #15

The End Goal

ISIP process step: Set Crash Reduction Goal

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Slide #16

ISIP process step: Expand Current Approach to Achieve Goal

Traditional

Comprehensive

Systemic

Speaker's Notes:

ISIPs are meant to lead agencies to think systemically.

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Slide #17

Night retro border five-section signal head –  Photo shows a traffic signal in the red phase at night. Only the red light and the retro-reflective backplate border are visible in the darkness.Signalized Intersections

MO flasher –  Photograph of a "Watch for Entering Traffic" sign on the right side of a suburban street. There are two flashers above the sign. The flashers are activated by loops for many MO sites.Stop-Controlled Intersections

ISIP process step: Identify Intersection Countermeasures

MO US 54. –  Aerial view of a section of US 54 in a rural area. An overlay of thin lines show the path where a vehicle could make a U-turn and change direction of travel on US 54 in Missouri.Signalized and Stop-Controlled Intersections

Speaker's Notes:

Type of intersection control provides a natural classification of countermeasures, whether (1) specific to signalized intersections, (2) specific to stop-controlled intersections, or (3) applicable to either type.

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Slide #18

Stop-Controlled Intersections

ISIP process step: Identify Intersection Countermeasures

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Slide #19

Signalized Intersections

ISIP process step: Identify Intersection Countermeasures

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Slide #20

Both Stop-Controlled and Signalized Intersections

ISIP process step: Identify Intersection Countermeasures

Speaker's Notes:

The data analysis will follow this general process.

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Slide #21

ISIP process step: Analyze Data, Identify Target Intersection

Separate Intersection Crashes into Sub-Groups

Determine Target Crash Types

Calculate Average Crash Costs and Severities

Determine Distribution of Crash Densities

Prepare Data Analysis Package


Slide #22

Crashes Sub-Groups

ISIP process step: Analyze Data, Identify Target Intersection
State rural signalized Local rural signalized
State urban signalized Local urban signalized
State rural stop-controlled Local rural stop-controlled
State urban stop-controlled Local urban stop-controlled

Speaker's Notes:

Classifying intersection crashes according to maintaining agency, area type, and control type can yield the following sub-groups.

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Slide #23

Sample Table

ISIP process step: Analyze Data, Identify Target Intersection
STATE Area Type Total # of Crashes Fatal A B C PDO Unknown
Signalized Rural 8,134 40 276 953 1,454 5,361 50
Signalized Urban 131,363 381 3,396 15,649 29,749 81,289 899
Unsignalized Rural 14,819 206 749 2,160 2,556 8,985 163
Unsignalized Urban 84,564 340 2,009 9,059 17,520 54,620 1,016
Unknown Rural 1,431 11 37 150 225 1,001 7
Unknown Urban 15,043 87 278 1,136 2,624 10,784 134
Subtotal   255,354 1,065 6,745 29,107 54,128 162,040 2,269
LOCAL                
Signalized Rural 1,141 4 24 133 173 800 7
Signalized Urban 137,033 267 3,102 16,670 34,459 81,486 1,049
Unsignalized Rural 6,942 35 225 803 1,023 4,605 251
Unsignalized Urban 176,886 434 3,983 19,664 38,102 108,761 5,942
Unknown Rural 458 1 11 45 58 337 6
Unknown Urban 19,368 100 332 1,542 3,979 13,056 359
Subtotal   341,828 841 7,677 38,857 77,794 209,045 7,614
OTHER                
Signalized Rural 17 0 0 2 4 11 0
Signalized Urban 2,739 5 88 443 685 1,504 14
Unsignalized Rural 190 0 4 30 21 131 4
Unsignalized Urban 2,077 6 43 190 384 1,405 49
Unknown Rural 15 0 0 0 1 13 1
Unknown Urban 208 0 3 24 36 140 5
Subtotal 5,246 11 138 689 1,131 3,204 73

Speaker's notes:

Here is an example of such data from one State. Note that, depending on the sources and quality of the data, there may need to be some "unknown" categories.

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Slide #24

Working With Data

ISIP process step: Analyze Data, Identify Target Intersection

Speaker's Notes:

No agency's system is perfect, but sound conclusion can be drawn and decisions made based on the information that is available.


Slide #25

ISIP process step: Develop Straw Man Outline

Establish Threshold Crash Levels

Develop Detailed Tables for Each Countermeasure

Compile a Summary Outline

Speaker's Notes:

The "straw man outline" refers to the high-level benefit-cost analysis that should be coordinated for the intersection countermeasure considered. Crash thresholds can be used to influence the numbers of instructions targeted based upon the anticipated funding and much of the ISIP. Construction and maintenance costs are compared to the expected monetary benefits from crashes prevented in the B/C analysis.

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Slide #26

ISIP process steps: Conduct Workshop to Refine Countermeasures and Budget; Develop Draft ISIP; Present Daft to Upper Management; Implement Management Suggestions; Implement Plan, Monitor Progress, Evaluate Results

Look for opportunities to integrate the ISIP with other statewide programs and funding streams:

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Slide #27

Noteworthy Practice: Ohio

Stop Controlled T-Intersections –  Diagram of typical signage present at a T-intersection, where the major road is horizontally at the top of the image. The Minor approach has "STOP AHEAD" signs on either side of the road and a STOP sign just before the intersection. Directly across is a sign indicating two-way traffic. The major road has "T-intersection ahead" signs on both sides of the road for both directions of travel. On the left half of the major road, the approach has a STOP sign.

A typical signing detail for stop-controlled T-intersections. This image was included in a slide presentation that the ODOT central office provided to the districts.

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Slide #28

ISIP process steps: Conduct Workshop to Refine Countermeasures and Budget; Develop Draft ISIP; Present Daft to Upper Management; Implement Management Suggestions; Implement Plan, Monitor Progress, Evaluate Results

Engage local agencies, MPOs/RPOs, and other stakeholders to enhance:


Slide #29

Noteworthy Practice: Texas

TX ISIP graph: Bar graph shows percent of various intersection types and KA crashes at those various intersection types. Roughly 55% of intersections in Texas are local urban unsignalized, 12% state urban unsignalized, 11% local urban signalized, 6% state urban signalized, 4% state rural unsignalized, 2% local urban unknown, 3% local rural unsignalized, 1% percent state urban unknown, and 1% state rural unsignalized. KA crashes are broken down into roughly 28% at local urban unsignalized intersections, 15% at state urban unsignalized, 20% at local urban signalized, 21% state urban signalized, 5% state rural unsignalized, less than 1% at local and state urban unknown , 2% at local rural unsignalized and state rural signalized. A text box at the top says "Most significant overrepresentation," and indicates the much higher percentage of accidents than intersections at local urban signalized and state urban signalized.

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Slide #30

ISIP States

ISIP States –  Map of the United States, with States participating in ISIP highlighted. Those highlighted include Arizona, Florida, Georgia, Indiana, Louisiana, Massachusetts, Mississippi, Missouri, New Hampshire, New Jersey, New York, North Carolina, Ohio, Oklahoma, Oregon, Pennsylvania, South Carolina, Tennessee, Texas, and Washington.

Speaker's Notes:

States with ISIPs: Washington, Oregon, Arizona, Texas, Oklahoma, Louisiana, Missouri, Mississippi, Florida, Georgian, South Carolina, North Carolina, Tennessee, Indiana, Ohio, Pennsylvania, Maryland, New York, New Hampshire, Massachusetts

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Slide #31

Other Lessons from ISIP States

Speaker's Notes:

By formally adopting the ISIP, States were able to garner buy-in from decision makers, integrate the plan with other plans (SHSP), and develop policy changes. On the other hand, other States found that a draft ISIP is more flexible and can change when new data or funding becomes available.


Slide #32

ISIP Implementation

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Slide #33

Implementation Strategies

Night retro border five-section signal head –  Photo shows a traffic signal in the red phase at night. Only the red light and the retro-reflective backplate border are visible in the darkness.Partial Systemic

MO US 54. –  Aerial view of a section of US 54 in a rural area. An overlay of thin lines show the path where a vehicle could make a U-turn and change direction of travel on US 54 in Missouri.Corridor Systemic

MO flasher –  Photograph of a "Watch for Entering Traffic" sign on the right side of a suburban street. There are two flashers above the sign. The flashers are activated by loops for many MO sites.Full Systemic

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Slide #34

Night retro border five-section signal head –  Photo shows a traffic signal in the red phase at night. Only the red light and the retro-reflective backplate border are visible in the darkness.Partial Systemic

Photo shows a two lane approach to a rural, stop-controlled intersection. There is a double yellow line down the center and a "Stop Ahead" sign on both sides of the road.

Approach:

Typical Treatments:

Speaker's Notes:

Partial systemic: Treating locations with low to moderate crash histories, with a focus on widespread deployment of only low cost packages of improvements

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Slide #35

MO US 54. –  Aerial view of a section of US 54 in a rural area. An overlay of thin lines show the path where a vehicle could make a U-turn and change direction of travel on US 54 in Missouri.Corridor Systemic

Aerial view of a j-turn on US 54 in a rural area. An overlay of thin lines show the previous paths of travel, with a smaller road coming from the upper right of the image having to cross directly across both directions of US 54 to reach Heritage Hwy.

Approach:

Typical Treatments:

Speaker's Notes:

Corridor systemic: Consistent treatment of multiple intersections along an extended distance of roadway with the low-cost treatment packages. Multiple intersections identified as low to moderate crash histories along a defined corridor

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Slide #36

MO flasher –  Photograph of a "Watch for Entering Traffic" sign on the right side of a suburban street. There are two flashers above the sign. The flashers are activated by loops for many MO sites.Full Systemic

Cross road with flashers –  Photo shows a road in a rural area. On either side of the two lanes is an "Intersection Ahead" sign with a 45 MPH sign and a sign with the names of the cross streets below. Above, both signs have a flasher with a solar panel to power them. Stop Ahead Sign –  Photo shows a Stop Ahead sign to the right of a two-lane, rural road in Utah with no paved shoulder. Further along the road is a stop-sign at the approach to a three-legged intersection.

Approach:

Speaker's Notes:

This is the most difficult of the three, as many States face barriers associated with data.

Speaker's Notes:

This is the most difficult of the three, as many States face barriers associated with data. Full Systemic: Treating intersections entirely on risk characteristics identified through rigorous safety data analysis. This is the most difficult of the three, as many States face barriers associated with data.

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Slide #37

Project Letting and Bidding

In-House

External Contractor

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Slide #38

Noteworthy Practice: South Carolina

Signal Ahead –  Photo shows a "SIGNAL AHEAD" sign on the right side of a South Carolina suburban road. Beneath the sign is a smaller sign indicating that the intersecting road is "Two Notch Rd".

Advance Signal Ahead warning sign with cross street name. Source: SCDOT.

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Slide #39

Policies and Standards


Slide #40

Noteworthy Practice: Missouri

Multiple reflectorized backplates –  Photo shows a three-phase traffic signal mounted on a mast arm at a rural intersection in New York State. In the background of the image, there is another visible mast arm with two traffic signals. All three signals have reflectorized backplates.

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Slide #41

Funding Optimization


Slide #42

Noteworthy Practice: Pennsylvania

Intersection Ahead signs –  Photo shows a section of rural Pennsylvania road with "Intersection Ahead" signs on either side of the road. Underneath are mounted "40 MPH" signs. Mounted above are signs with the name of the cross street and two yellow flags apiece.

Signage upgrades that include doubling up the intersection warning signs, adding cross street names, and yellow flags above the signs. Source: PennDOT.

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Slide #43

ISIP Evaluation


Slide #44

Evaluating the Systemic Approach

Speaker's Notes:

After implementing several systemic countermeasures across the State, Florida has consistently met their goal of 5% reduction in fatalities and injuries. However, it is hard to determine if this decrease is a direct result of the systemic approach or other contributing factors.

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Slide #45

Success Stories From the Field

Louisiana –  Illustration of the silhouette of Louisiana. South Carolina –  Illustration of the silhouette of South Carolina.

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Slide #46

LA DOTD Experiences

Speaker's Notes:

To date this has all been done though a Rural Safety Innovation Program grant received from FHWA. LADOTD received $4.1 million of RSIP funds. $2.0 million was awarded for rural intersection treatments and $2.1 million was awarded for roadway departure treatments. Only locations in the Delta Parishes were eligible for these funds. LADOTD let to construction their first 104 intersections which included 88 rural stop controlled intersections and 16 rural signalized intersections. Construction was completed in December 2010.

The bids on the initial project came in under estimate, so LADOTD was able to let to construction an additional 100 intersections in September 2010. They also supplemented the leftover RSIP funds with regular safety funds for this project. LADOTD were able to do 90 rural stop controlled intersections and ten rural signalized intersections. The average cost per intersection was $10,000.

Instead of doing a statewide project for its next round of improvements, LADOTD decided to limit their project to individual districts. In Louisiana, there are nine DOTD districts that will let nine separate projects. LADOTD also decided to take a corridor approach and address both intersections that are in the action plan and curves that they identified as needing low-cost countermeasures.

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Slide #47

Louisiana Results

Rural 4-leg Stop:

Stop Ahead in before condition –  Photo shows a section of rural road with "Stop Ahead" signs on either side. Stop Ahead in after condition –  Photo shows the same section of rural road as the previous image, but both "Stop Ahead" signs have been replaced with larger versions, mounted on two posts apiece.

53% reduction All Crashes

64% reduction Severe Crashes

Rural 3-leg Stop:


67% reduction All Crashes

56% reduction Severe Crashes

Three-legged intersection approach in before condition –  Photo shows a stop-controlled approach to a rural intersection. There are two STOP signs visible at the top of the approach, one on each side. Three-legged intersection approach in after condition –  Photo shows the same stop-controlled intersection as the previous image, but both STOP signs have been replaced with larger versions, mounted on two posts apiece.

Louisiana evaluation can be found at safety.fhwa.dot.gov/local_rural/delta/

Speaker's Notes:

This is a before shot of an intersection where LADOTD implemented LADOTD improvements. Note that staff had previously doubled up on the advanced warning signs.

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Slide #48

South Carolina Results

Dual post Stop Ahead sign –  Photo shows a Stop Ahead sign mounted on two posts to the left of a rural road.

Stop-Controlled

Signalized

Reflectorized backplate during daytime –  Photo shows a five-phase signal with a reflectorized backplate. Reflectorized backplate during nighttime –  Photo shows the same five-phase signal as the previous image during nighttime. Only the currently-lit green signal and the backplate are visible in the darkness.

Speaker's Notes:

The experience in South Carolina has been the subject of an ongoing evaluation by the Evaluation of Low Cost Safety Improvements-Pooled Fund Study. This empirical-Bayes evaluation encompasses a 10-year timeframe (2005 through 2014), with low-cost treatments at 84 signalized intersections and 433 stop-controlled intersections. Results for the signalized intersection treatments show a 10.7-percent reduction in fatal and injury crashes and an 11.7-percent reduction in right-angle crashes, both at a 95-percent confidence level. A 4.5-percent reduction of total crashes at the 90-percent confidence level was found as well. Results for the stop-controlled intersection treatments show an 8.3-percent reduction in total crashes, a 10.7-percent reduction in fatal and injury crashes, 6.7-percent reduction in rear-end crashes, 5.9-percent reduction in right-angle crashes, and 14.7-percent reduction in nighttime crashes. All results for stop-controlled are statistically significant at the 95-percent confidence level with small standards of error.

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Slide #49

Success Stories From the Field

Louisiana

South Carolina

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Slide #50

Summary


Slide #51

ISIPs–Overall, a Success Story

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Slide #52

Other Useful Resources

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Slide #53

Other Useful Websites

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Slide #54

For More Information…

Jeffrey Shaw, P.E.
FHWA Office of Safety

Jeffrey.Shaw@dot.gov
(708) 283-3524

safety.fhwa.dot.gov/intersection/

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Page last modified on February 1, 2017
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