Data-Driven Safety Analysis - Pennsylvania State … Data-Driven Safety Analysis initiative provides tools ... \爀屲These approaches use crash, ... Or do they express related yet
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Data-Driven Safety Analysis Integrating Safety Performance into ALL Transportation Investment Decisions
Integrating Safety Performance into ALLTransportation Investment Decisions
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Today we’re going to provide an introduction to Data-Driven Safety Analysis and how it can be used to integrate safety performance into ALL transportation investment decisions.
The EDC Data-Driven Safety Analysis Initiative…
Goal: Integrate safety performance into ALLtransportation investment decisions
2Source: FHWA
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The Data-Driven Safety Analysis initiative provides tools and methods to help accomplish this, giving us confidence in what we can expect before we build a project. DDSA helps you make more informed decisions, allowing you to better target our transportation investments, which will lead to fewer fatalities and serious injuries on our nations roadways. Beth mentioned that DDSA was continuing under EDC-4. One area that will be more strongly addressed in Round 4 will be applying DDSA on Local Roads, where approximately half our fatalities occur. Our effort will include tools and resources for local data collection and integration, development of Local Road Safety Plans, and project-level safety analysis.
What is DDSA?•The application of the latest evidence-based tools and approaches to safety analysis •Provides reliable estimates of an existing or proposed roadway’s expected safety performance•Helps agencies quantify the safety impacts of transportation decisions, similar to the way agencies quantify:
Source: AASHTO, AASHTOWare, Roadway Safety Foundation
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DDSA is the application of the latest evidence-based tools and approaches to safety analysis. These approaches use crash, roadway, and traffic volume data to provide reliable estimates of an existing or proposed roadway’s expected safety performance. DDSA helps agencies quantify the safety impacts of transportation decisions, similar to the way agencies quantify: traffic growth environmental impacts traffic operations pavement life construction costs
Foundational DDSA Methods: the AASHTO Highway Safety Manual, first edition
The foundational DDSA methods are contained within one primary document…the Highway Safety Manual. The HSM published by AASHTO compiled decades of research conducted by Transportation Research Board, State DOTs, and FHWA into one location. The first edition was published in 2010, which contained crash prediction models for rural two-lane roads, multilane rural highways, and urban/suburban arterials. The models for freeways and freeway interchanges were added in 2014 as a supplement.
A Document Akin To the HCM…
Definitive; represents quantitative ‘state-of-the-art’ information
Widely accepted within professional practice of
transportation engineering
Science-based; updated regularly to
reflect research
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The Vision for the HSM
5Source: Transportation Research Board
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The vision for the HSM was akin to the Highway Capacity Manual… The Highway Capacity Manual is acknowledged to be the recognized source of information and methodologies for quantitatively evaluating traffic operations on streets and highways. Engineering studies and reports that use the HCM are unquestioned with respect to the results. The HCM contents are based on peer-reviewed, science-based research; the HCM is continually updated and improved as more research is completed. No such document exists in the field of quantitative highway safety. While there is quantitative safety information available, much of it is in conflict, may not reflect the best scientific methods, or is unclear in its contents and background. Engineers and planners who need to include quantitative safety information in their work are left to their own knowledge base and must not only make judgments about what data or methods to use, they must also defend their judgment. The HSM is a toolbox for assessing quantitative safety effects of decisions or actions – nothing more. The HSM provides direction on how to use each of the tools contained within it, and how to interpret and communicate the results. It also provides direction on which tools are appropriate to use in a given situation or given the amount and quality of data available. The HSM provides the user with the tools to assess different alternatives to reduce crash frequency or severity. With publication of an HSM, users can refer to it with confidence that it reflects best practices and knowledge and that it has been ‘vetted’ by highway safety research professionals.
The HSM has resulted in the development of:
• Spreadsheets
• Software Products
• Guidance Documents
• Crash Modification Factors Clearinghouse
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The HSM has resulted in the development of spreadsheets, software products, guidance documents and the Crash Modification Factors Clearinghouse, all with the goal of helping automate the implementation of the approaches contained in the HSM.
but DDSA tells us they would perform very differently from a safety perspective.
Source: CH2MHILL
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On this slide, you see illustrations of possible design alternatives for a suburban arterial. All three meet current design standards, and perhaps to the “naked eye”, some make think these designs would perform similarly. That’s where DDSA can help. It shows that they would perform very differently from a safety standpoint. In fact, Alternative two would reduce fatal and injury crashes by 60%. These tools can helpful in informing us and our staff, informing elected officials, and even the traveling public. Source: CH2MHILL, Integrating the HSM into the Highway Project development Process, FHWA May 2012.
Nominal Safety Substantive
Safety
Examined in reference to compliance with standards, warrants, guidelines and sanctioned design procedures
The expected or actual crash frequency and
severity for a highway or
roadway
Approaches for Considering Safety
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Source: AASHTO Source: AASHTO
*Adapted from Ezra Hauer, ITE Traffic Safety Toolbox Introduction, 1999
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Key Message: Highway engineers are used to thinking about safety in terms of adherence to design criteria such as are published in the AASHTO Green Book. This is referred to as ‘nominal safety’. The performance of a highway (either existing or expected) as determined by crash frequency and severity, is referred to as ‘substantive’ or quantitative safety. The HSM provides this added dimension to the knowledge base of highway designers. Background: The term “nominal safety” was coined by Dr. Ezra Hauer to describe characterization of a situation in terms of its adherence to design standards and practices. We can think of a road as “nominally safe” if it meets the minimum standard of care and is current with respect to published standards and guidelines. The term substantive safety (or perhaps quantitative safety) is its actual or expected performance in terms of crash frequency and severity. Note that substantive safety is a function not only of the basic characteristics of the road, it is also a function of maintenance, law enforcement and other resources we choose to devote to its operation. Interactivity: The instructor could ask participants whether the two dimensions of safety are the same? Or do they express related yet fundamentally different information about a highway?
Nominal vs Substantive Safety
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Clearly, the two dimensions of safety differ. If think of safety as “risk” (Y-Axis) and the characteristics of a highway (design dimensions, operating and maintenance practices, etc) (X-Axis) as descriptors, we can apply a “mental model” of safety based on design standards and criteria, “nominal safety”, that is simple and straightforward. A roadway either meets standards or it doesn’t. Such standards are by their nature “hardlined”, so the exercise of characterizing the nominal safety of any situation is readily accomplished. The contents of the HSM, though, provide insights lacking in the nominal safety model. These insights are intuitively understood by most transportation professionals. Incremental changes in design dimensions (lane width, shoulder width, radius of curve, stopping sight distance, etc.) have incremental effects on substantive safety (if they have any effect at all). Thus, as a curve gets a bit sharper the risk of a crash increases slightly if at all. Thus, if one were to try to model or characterize this effect it would follow something like the orange line. Moreover, where the orange line may fall depends on factors such as the type of facility, its “context”, and a wide range of considerations not described by the roadway’s basic design characteristics. How much “risk” might we expect – an additional 10 crashes a year? 1 crash a year? 0.1 crashes a year? Does it not follow that understanding risk levels in these terms is or should be helpful to decision-making? Many decisions or actions we take as professionals involve marginal or incremental differences among alternatives. The HSM informs these decisions by providing the tools and approaches to characterize the shape and values of the substantive safety curve for the range of highway types and conditions we typically encounter.
Where can DDSA be applied in the Project Development Process?
Source: FHWA10
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So where can DDSA be applied in the Project Development Process? Really, it can be applied throughout, and we’ve tried to boil it down to four broad stages. It can be applied in planning, alternatives analysis, design, as well as construction, operations, and maintenance. We’ll talk more about these stages in a moment, but first I want to turn it over to my colleague, and co-team lead John McFadden from the FHWA Resource Center’s Safety and Design Technical Services Team. John, could you please lead us in a discussion about how we as professionals can provide “the highest and feasible level of safety”?
Applying DDSA in Project Development Process
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The key here is to remember the crystal ball and that we can quantify how a roadway could, should, and will perform from a safety perspective.
DDSA in Planning12
Source: FHWA
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Thank you, Jerry. In this section, we will cover where safety fits into the planning process, for both system level planning and project level planning.
DDSA in the Planning Process
DDSA tools can be applied to help identify which roadways aren’t performing as they should, determine the scope and need of potential projects, and prioritize them.
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Planning sets the stage for the project development process and DDSA tools can be applied early in the planning process to help identify which roadways are not performing as they should, determine the scope and need of potential projects and prioritize them.
There are two distinct ways data driven safety analysis can be utilized in the planning process: system level planning and project level planning. In system level planning, data-driven safety analysis can be used as a tool in screening your transportation network. In project-level planning, data driven safety analysis can be used in establishing project scope and prioritizing projects.
What is network screening? Network screening is the process of identifying which sites have the most potential for safety improvement. Let’s go through and example. In a typical network screening process, you would first establish a focus. A typical focus would be roadway departure crashes. Then the practitioner would identify a network, for example, the local road system. The next step would be to select performance measures, such as fatal crashes or fatal and serious injury crashes combined. The fourth step, which is most critical for DDSA, is selecting a screening method. Traditional screening methods are based on frequency, often times with a threshold for a number of crashes at a location. We will discuss Step 4 more on the next slide. The last step is to screen and evaluate results, which would result in the creating of a list of locations with potential for safety improvement.
Traditional vs. Advanced Network ScreeningFrom simple safety performance measures:• Crash frequency• Crash rate• Equivalent property damage only (EPDO)
To advanced safety performance measures:• Excess Predicted Average Crash Frequency• Level of Service of Safety• Potential for Safety Improvement• Systemic Sites with Promise
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What I just described in step 4 of the network screening process is an example of the traditional network screening methods, using crash frequency, crash rate or property damage only crashes. DDSA allows us to use advanced safety performance methods for network screening, such as excess predicted average crash frequency, level of service of safety, potential for safety improvement and systemic sites with promise. Let’s look at an example of the Level of Service of Safety method as used by Montana DOT.
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Level of Service of Safety
Tool: Agile Assets Safety Analyst
Credit: Montana DOT
Example: Montana DOT - Network Screening
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As an alternative to using more basic methods for evaluating safety, Montana DOT has performed advanced safety analysis for network screening by using the level of service of safety or LOSS method. The LOSS method compares a roadway segment’s observed crash frequency and severity to the crash frequencies and severities predicted by safety performance functions. The comparison relies on the standard deviation of predicted crashes to assign a roadway segment to a particular level of safety. The four LOSS categories indicate a potential for crash reduction from high to low. As you can see from the locations plotted in red in the LOSS 4 category, Montana DOT identified a list of sites with high potential for safety improvement based on a potential for crash reduction, not the highest ADT or number of crashes.
Now let’s look at data driven safety analysis in the context of project level planning. Establishing project scope and performing project prioritization are two areas where safety analysis can play a role in project level planning.
Establishing Project ScopeTypical process:1. Assess the performance of the existing site
• Condition/status of pavement, structures, congestion, safety, etc.
2. Propose improvements
3. Determine necessary funding and schedule
• Done at a level commensurate with the type and scale of the project
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A typical process for establishing project scope looks like this. First, assess the performance of the existing site through various analyses, one of which can be safety. Then propose improvements and determine funding and schedule. An analysis of safety impacts is typically done at a level commensurate with the type and scale of project.
• The Transportation Safety Management & Operations (TSM&O) Evaluation consists of three parts
• Safety, Operations, and ITS analyses
• The TSM&O Evaluation makes recommendations for improvements related to Safety, Operations, and ITS
• All projects require a TSM&O Evaluation.
Example: Colorado DOT Safety Analysis in Scoping
Safety Operations ITS
TSM&O Evaluation
Recommendations
Improvements Incorporated in Project
Credit: Colorado DOT
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An example of safety analysis in project level scoping can be found in Colorado DOT’s Transportation Safety Management and Operations Evaluation (or TSMO) process. Colorado DOT uses DDSA along with operations and ITS, in all projects as part of the TSMO evaluation. The evaluation results in recommendations for improvements that may be incorporated into the project. And since all projects require a TSMO evaluation, safety plays a role in project level scoping for all projects.
• Region and HQ provide the safety analysis to Project Manager • Can include
DE/PBPD analysis• PM can make data-
driven decisions when adjustments to the scope can be made
• DDSA concepts now more familiar to PM, rather than SMEs
Example: CO DOT - Safety Analysis in Scoping
Credit: Colorado DOT
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Safety analysis as part of the TSMO process allows safety impacts to be analyzed early enough in the project development process to allow project managers to adjust the project scope if needed.
Safety Analysis in Project Prioritization
Typical process:• Identify criteria for scoring projects• Develop list of potential projects• Apply scoring methods for each criteria• Rank and prioritize list of projects
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The second use of DDSA in project level planning is project prioritization. The typical process for project prioritization begins with identifying criteria for scoring projects, followed by developing a list of potential projects, then applying scoring methods for each criteria and ranking and prioritizing the list of projects.
Example: Virginia DOT – Safety Performance in Project Prioritization
Category B 15% 20% 25% 20% 10% 10%Category C 15% 25% 25% 25% 10%Category D 10% 35% 15% 30% 10%
Project Weighting Factors
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Credit: Virginia DOT
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Virginia DOT considers safety among other needs, such as congestion mitigation, accessibility and land use, when prioritizing projects. As part of their program SMART SCALE, Virginia is divided into categories based on urban and rural characteristics. Each project’s needs are given a weight dependent upon that category. For example, safety has a lower weight in category A, which is an urban area where data shows safety is less of an issue, and safety has a higher weight in category D, which is a rural area of the state where data shows safety needs more weight in consideration.
Example: Virginia DOT - Planning-Level CMFs for each project type
Credit: Virginia DOT
1. Countermeasures and CMF values combined to develop 1 CMF for each project type • e.g. CMF = 0.80 (20% crash reduction)
2. CMF applied to previous crash history • e.g. 2 F+SI Crashes avoided per year
3. This value is used for the safety portion of the project score
e.g. converting 2-lane road to 4-lane divided:
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To determine the weighted safety score, 50 percent of the score is determined by the expected reduction in total fatalities and serious injuries. The remaining 50 percent is a result of the expected reduction in the rate of fatalities and serious injuries per 100 million vehicle miles traveled. Virginia DOT uses planning level crash modification factors (or CMFs) to determine these percentages. To develop planning level CMFs, once the project type and improvement are determined, a range of associated CMFs are identified for the project. These CMFs are basically averaged together to calculate an overall planning level crash modification factor for the proposed improvement. This planning level CMF is used as the basis for the safety portion of the project score.
DDSA in Alternatives Analysis27
Source: FHWA
DDSA in Alternatives Analysis
DDSA tools can predict the number and severity of crashes for each project alternative, allowing safety performance to be considered along with other project criteria.
So what the graphic shows is our normal steps in developing a NEPA document …on one side of this process are steps in the safety evaluation, and on the other engagement with your project stakeholders. As we know the process starts with project scoping, and developing a purpose and need statement, then evaluating alternatives, and finally assessing the impact, benefits, and potentially mitigation if appropriate. The safety performance of the project certainly has social, economic, and environmental impacts. Here the key takeaway is that you can use these safety tools to really craft your purpose and need, and use it to evaluate project benefits.
When might a more-robust safety analysis in the environmental phase be appropriate?
• When Safety is included in the Purpose and Need
• Projects that claim a safety benefit
• Projects where there could be a substantial difference in safety for the alternatives being considered
• Projects with existing safety issues
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So when might a more robust safety analysis in the environmental or alternative analysis phase be appropriate? Our advice is to really start to focus in on those projects where safety is strongly stated in the purpose and need, or where there is a project that claims a safety benefit, or where there are substantial differences between alternatives.
Purpose and Need example…
Evaluation CriteriaNo-Build
Alternative Alternative 1 Alternative 2 Alternative 3
InfrastructureCondition
Ability to preserve or enhance infrastructure
Poor(pavement rated “poor” in 2010)
Good(new pavement)
Good(new pavement)
Good(new pavement)
Safety Improvements
Ability to implement safety features and reduce crashes
Now we can all think of at least one purpose and need statement that was lacking, perhaps more if we’re willing to admit. So what I have here is one project recently reviewed where we had two primary needs - pavements and safety. We have three alternatives which differ in cost by $4.3M. I won’t speak to the level of performance desired for the pavement folks, but for the safety criteria, we Now I am going to leave it to the pavement and materials folks to comment on the infrastructure need and I’ll just focus on the safety section and lack of data or objective evidence. So this graphic was pulled from the NEPA document. And what we originally had in the purpose and need discussion, and I’ll paraphrase here, was in 1999 we had a task force convince some pretty important people that we had a major safety problem so we got some federal dollars earmarked and we have to spend them on safety, and pavements. Like I said we had that statement but got rid of it to make sure everyone (meaning me) kept their jobs. So what you can see here are three alternatives that are actually different alignments and you can see the lack of substantive information to distinguish these three alternatives. So although the cost of the project was well over $17M (and a range in cost of $4.3M) there was little to actually quantify the safety need or benefit. Whereas the point of DDSA is to make more informed decisions, so we can target our investments, with the ultimate goal of reducing fatal and serious injuries. So we all hear everyone is trying to be cost conscious, and that budgets are tight, and we also hear everyone say safety is job #1 but here we have a $4M spread with no notable differentiation in performance. Not the best example.
Example – Burlington County, New Jersey Intersection
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Credit: Burlington County
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So here is a good example from Burlington County, New Jersey where a signalized intersections and roundabout were two alternatives considered. This was actually developed into one of our feature EDC case studies which captures a more collaborative process between FHWA , New Jersey DOT, Burlington County, and the DRVPC (Deleware Valley Regional Planning Commission).
Alternatives Analysis: signalized Intersection vs. Roundabout• Feb 2012: fatal crash involving school bus occurs• Sept 2012: HSIP funding would require HSM analysis• Oct 2012: DVRPC offers to assist Burlington County with
HSM Analysis• Jan 2013: HSIP project application submitted & approved• Jun 2014: Roundabout opened to the public
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Example – Burlington County, NJ Intersection
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Alternative 1Signalized Intersection
Alternative 2Modern Roundabout
Benefit(Crash Reduction) $587,657 Benefit
(Crash Reduction) $1,296,097
Cost (Construction) $1,113,029 Cost (Construction) $1,090,950Benefit/Cost Ratio 0.53 Benefit/Cost Ratio 1.19
Credit: New Jersey DOT
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In 2012 this location saw a very gruesome crash involving a school bus and dump track which made national headlines. The location was a stop controlled intersection, and one of the fatals onboard was actually the daughter of a state trooper. Tragedies like this make for a very emotionally charged situation. In this case also NTSB got involved, along with other locally elected officials, and the greater community who were immediately calling for a signal to be installed which highlights another important aspect of DDSA, the ability to de-escalate some emotionally charged and sometimes subjective conversations regarding safety. Additionally in this local area roundabouts, or the modern roundabout which is a proven safety countermeasure was considered new technology. But lucky for this project there were great champions at DVRPC and Burlington County to help navigate this concern and bring this project to the finish line. Advance to alts 1 and 2: So because HSIP funds were being targeted an HSM analysis also needed to be completed to support the application. This analysis really highlighted the difference in benefits between the two alternatives, which was then carried into the benefit/cost calculation which helped bring some confidence into the decision making process and get everyone on-board with the preferred alternative. What was a lot of public outcry for signals, turned into public support and acceptance of a roundabout. All in somewhat short order. So in about a year actually the evaluation was completed and the project was approved. And then in June of 2014 it was opened to the public. So if you look at the graphic it is pretty clear that the ability to quantify safety allows us to start having more meaningful conversations and start making better targeted investments.
Example: Louisiana DOTD – EIS Alternatives Analysis
I-12 to Bush, LA Four alternatives were considered to replace a two-lane, un-divided roadway with a four-lane, divided roadway with controlled access• All four alignments
predicted a reduction in crashes from the No Build alternative
Credit: Urban Systems, Inc.and Louisiana DOTD
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Potential Reduction in Crashes, Costs
Example: LA DOTD – EIS Alternatives Analysis
Credit: Louisiana DOTD
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As you can see the 5 alternatives were also ranked with the top being the best performer from a safety perspective and the no build the worst. You can also see the analyst period was twenty years out to 2035.
Benefits from use of IHSDM• Quantify safety costs and benefits• Safety given equal weight in comparative
analysis
Corps of Engineers selected Alternative Q, which had a predicted crash reduction of 6% and a $1.5M cost savings to society
Example: LA DOTD – EIS Alternatives Analysis
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Another interesting piece of this analysis was working across multiple resources and resource agencies include the Army Corps led the project team to select alternative Q. So again using DDSA or the crystal ball does not force you to select an alternative but it does allow you to quantify safety performance, and have a much richer discussion on impacts across alternatives.
DDSA in Design
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Source: FHWA
DDSA in the Design Process
DDSA can be used to determine optimal design criteria, considering both safety and cost. • DDSA helps justify
flexibility in design • design exceptions• performance-based
practical design
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Will be discussing how DDSA can be used during the design process, particularly for evaluating design exceptions and implementing performance-based practical design. Performance-based practical design implemented with DDSA has great potential. State and local agencies have way more needs and problems to solve than available funding. Performance-based practical design using DDSA can result in projects that are much more cost effective. This allows limited funds to be stretched further and many other needs across the highway system can be addressed.
Performance-based Practical DesignAn approach to decision-making that encourages engineered solutions rather than reliance on maximum values or limits found in design specifications
Characteristics• grounded in performance management• exercises engineering judgment to address
purpose and need • uses appropriate performance-analysis tools• considers both short- and long-term project and
system goals40
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Performance-based practical design, coupled with DDSA, offers great potential for developing more cost-effective projects. Rather than defaulting to standard values in tables or choosing design dimensions that have seemingly worked well in the past, PBPD and DDSA offer a more sophisticated approach where design values and dimensions are derived from analysis. And rather than looking only at individual projects, PBPD looks at needs across the entire transportation system.
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Example: AZ DOT Analysis of Design Criteria
Alternative Improvements Included:• Widening to 5 ft shoulders• Widening to 8 ft shoulders
(MP 441 to 466)
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Credit: Arizona DOT
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A simple PBPD example from NE Arizona. 2-lane rural highway with very minimal shoulders (0-1 ft). DDSA was used to evaluate widening shoulders to either 5 ft or 8 ft.
Plot of Geometric Features and Expected Crashes Example – Arizona DOT
Credit: Arizona DOT
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Software tools are available to make DDSA more efficient during design. Arizona used the Interactive Highway Safety Design Model, which allows CADD files to be imported. The output in the bottom graph shows expected crashes by segment. The red line is the existing, minimal shoulders. The blue and green lines are the 5 and 8 foot shoulder options. The model shows significant improvement from the existing condition but a very small difference when comparing 5 ft vs 8 ft. Once alignment, traffic, and other data are entered into these software tools, it’s easy to look at a wide array of design dimensions. For example, the safety impact of various increments of lane and shoulder widths can be compared.
Crash Prediction ResultsExample – Arizona DOT
Safety Analysis:• Model was un-calibrated as used (not necessary for
comparative alternatives analysis)• Alternative B (8-ft shoulders) would reduce crashes
by 4 percent more than Alternative A (5-ft shoulders)
Credit: Arizona DOT
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The 8-foot shoulder option does have the lowest number of predicted crashes. The right-hand column shows a 21% crash reduction as compared to 17% for the 5-foot option (a small difference). This illustrates the sophistication of making design decisions with DDSA. This is a better approach than using “standard” values from Road Design Manuals or the AASHTO Green Book. It makes decision decisions more quantitative and objective, rather than opinion-based.
Example – Arizona DOT
Economic analysis:• Although Alternative B (8-ft shoulders) could
provide the greater benefit in reduction in fatal and injury crashes, Alternative A (5-ft shoulders) would provide the greater return on investment and was selected as the preferred alternative.
Credit: Arizona DOT
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When you bring cost into the equation, the 5-foot option comes out on top with a B-C ratio of 2.3 compared to 1.9 for the 8-foot option. The more cost effective design was chosen, freeing up funds to address safety or other needs on Arizona’s system.
Example: MN DOT – PBPDUS Hwy 10 Access Study
47Source: Bolton & MenkCredit: Anoka County and Minnesota DOT
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A larger example of using DDSA with performance-based practical design from MN. US Highway 10 is a high volume signalized expressway in suburban Minneapolis. The 7-mile corridor has ADT that ranges from 33,000 to 61,000 vpd. Over 10 years there were 13 fatal crashes, including 4 pedestrians. Many site constraints—adjacent BNSF rail line, high ROW costs, many access points. Previous studies all looked at conversion to a freeway. The cost estimate to do this (including ROW) is $300 million. A study was initiated that took a step back from this freeway vision and looked at more cost-effective designs, that could more realistically be funded and constructed, and still achieve most of the operational and safety benefits of a full freeway. The two layouts are examples of some of the designs considered. The bottom layout shows some alternative at-grade solutions. The top layout provides an overpass but with right-in/right-out connections, maintaining the expressway character of the highway, but with some grade separation. This first graph shows the cumulative operational benefits achieved by implementing groups of these lower-cost projects. Implementation through the “mid-term priority” group of projects (the green line) would achieve 90% of the operational benefits of full freeway conversion. At $100 million, or one-third the cost!
Example: MN DOT – Communicating PBPDUS Hwy 10 Access Study
48Source: Bolton & MenkCredit: Anoka County and Minnesota DOT
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This second graph shows how DDSA was used to quantify the cumulative safety benefits, similar to how the operational benefits were quantified. Implementation through the “mid-term priority” group of projects (again, the green line) would achieve about 90% of the safety benefits of full freeway conversion. At $100 million, or one-third the cost!
Construction, Operations, and Maintenance
Source: FHWA
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DDSA in Construction, Operations, and Maintenance
• Interstate Access Requests• Intersection Control
DDSA can be used in a more informed decisions in the construction I want to quickly address the three examples shown in black. First DDSA can be used to evaluate the safety impacts and safety cost associated with road improvements made as part of land development on it – projects and identified in traffic impact studies. Second, through the transportation management plan the safety impacts can sometimes be evaluated using DDSA. Finally, operational techniques such as part-time shoulder use can be justified using DDSA.
3. An operational and safety analysis has concluded that the proposed change in access does not have a significant adverse impact on the safety and operation of the Interstate facility …
5174 FR 165, pg. 43744 (2009)
Requests for a proposed change in access must include a description and assessment of the impacts and ability of the proposed changes to safely and efficiently collect, distribute and accommodate traffic…
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>> Let's start with interstate access requests. Assessing the operational and safety impact of new or modified interstate access is a critical element in preserving the function of the interstate highway system. Access changes cannot have a significant adverse impact on the safety of a State Facility. This is based on current and future your traffic projections. Also requests must include a description an assessment of impacts and ability of our post changes to safely collect and distribute traffic. For both current and future your traffic projections. DDSA can provide a quantitative research base method for determining and documenting the safety impact of interstate access changes.
Would you expect these alternatives to perform the same over a 30-yr project life?
Shouldn’t we know how alternatives will perform from a safety perspective before investing millions of taxpayer dollars?
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Source: CH2M
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>> So what you expect these alternatives to perform the same over 30 year project life? Interchanges will perform differently from a safety perspective over the life of the design and given the context and conditions of the project.
Safety performance analysis:– Model was un-calibrated
as used– Results used for
comparisons are relative– Focused on KAB type
crashes from 2015-2035•Alternative 8 predicted to have lowest KAB crash frequency and lowest expected societal cost•City of Dublin and ODOT selected Alternative 8 as the preferred alternative based on all of the criteria.
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Source: CH2M
Intersection Control Evaluation
• Purpose: Consistently consider and screen from among many proven combinations of geometry and traffic control when a new intersection or existing intersection modification is first contemplated.
• Goal: to identify and select an alternative that both meets the project purpose and reflects the overall best value, in terms of specific performance-based criteria within the available limited resources.
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>> DDSA can be applied with the intersection control evaluation framework, otherwise known as ICE. ICE is a process that a growing number of transportation agency use to provide a more holistic approach to intersection control. Far too often there is a bias in policy or Ewa individual engineering decision-making towards a particular intersection solution. The use of DDSA can assist in quantifying safety among other factors within the ICE framework. As it was previously shown in the New Jersey example, quantitative safety analysis can help make analytically informed decisions.
Example: Washington DOT - ICE PolicyWSDOT Design Manual M 22-01.12• Compare the
predicted crash frequency of the alternatives using the tools described in Chapter 321. Discuss how each proposed solution might affect safety performance and crash types. Credit: Washington DOT
>> This is example from Washington DOT ICE policy. In their design manual, a comparison of the predicted crash Birkins the of different alternatives is to be performed to. And a discussion of how each solution impact of safety performance a different crash types, it is to be provided as part of the design analysis.
Seven National Goals (MAP-21)• Safety• Infrastructure Condition• Congestion Reduction• System Reliability• Freight Mobility and Economic Vitality• Environmental Sustainability• Reduced Project Delivery Delays
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Presentation Notes
>> Finally, the last application I would like to present his performance management and its relationship with maintenance, projects, and DDSA. Map21 defined goals for the seven performance areas shown here in scoping and prioritizing projects. Some States are evaluating multiple performance simultaneously as a way to meet a variety of goals. Maintenance projects provide a great opportunity to address multiple system performance measures and targets.
State of RepairCRS Range
9.0 to 7.6 Excellent7.5 to 6.1 Good6.0 to 4.6 Fair4.5 to 1.0 Poor
IRI Range (in/mi)1 to 94 Good
95 to 177 Fair> 177 Poor
SRI RangeMinimal Good
Low MinorMedium Moderate
High Severe5% 5%
Evaluating bridge and pavement condition data alongside safety performance to prioritize projects
• Condition Rating System (CRS) –Structural: Loss of load carrying capacity or structural breakdown
• International Roughness Index (IRI) –Functional/Surface: Excessive roughness impacting functional usability and causing drive discomfort
• Safer Roads Index (SRI) – Safety Performance (PSI): Establishes safety risk based on historical severe crashes and exposure
Example: IL DOT - Performance Management
Credit: Illinois DOT
Safer Road Index & Performance Metrics
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Example: IL DOT – Performance Management
Credit: Illinois DOT
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Safer Road Index & Performance Metrics
Legend
Example: IL DOT - Performance ManagementSafer Road Index & Performance Metrics
Credit: Illinois DOT
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Stakeholder Implementation62
Available Resources to Advance Implementation
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DDSA Progress by States To-Date:
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Advanced under EDC-3
Achieved EDC Goal
Demonstration or Above
Assessment or Above
13 29 37 17Source: FHWA EDC-3 Period 3 Implementation Progress Report -- as of June 30, 2016
Source: FHWA
Presenter
Presentation Notes
The key message is that many (three out of four) States have applied (demonstrated) the use of DDSA on one or more projects. The goal under EDC-4 is to advance implementation to the Assessment and Institutionalized levels (meaning that DDSA is included in their policies and procedures). We also are hoping to see more local agencies demonstrate these tools.
Available DDSA Resources
• Fact Sheets and Case Studies• Articles and Infographics• Presentations• Videos• Exhibit Booth• Webinars• Guidance Documents• Training Workshops• Technical Assistance
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Presenter
Presentation Notes
Next, we’re going to touch on just some of the resources we’ve made available. We have a fact sheet and several printed case studies. There’s a number of articles and infographics that can be made available for re-publication in your newsletters and trade publications. We also can provide a presentation if you have an opportunity to speak about DDSA to your agency or peers. And I’ll touch on some these additional resources in more detail on the subsequent slides.
DDSA How-To Webinars• Safety analysis of freeways and interchanges• Integrating safety into all projects • Systemic Safety analysis approaches with limited
roadway data Office Hours – applications of the HSM when its not a 1:1 fit
• Using Advanced Safety Analysis Techniques for Network Screening
• Safety Performance Function Calibration and Development
• Interactive Highway Safety Design Model (IHSDM)
All recorded and available for download:http://www.fhwa.dot.gov/innovation/everydaycounts/edc-3/ddsa_resources/#webinars
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Presenter
Presentation Notes
We have conducted a number of DDSA “How-To” webinars, which have all been recorded and are available for download.
State Policies & Procedures on Use of the Highway Safety Manual
• Identifies existing HSM language in State policy/procedural manuals
• In areas with limited or no HSM language, provides sample language that a State could start with
• Language on each PD Phase• Available at:
Source: FHWA
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FHWA-SA-16-119
http://safety.fhwa.dot.gov/rsdp/hsm/spp/
Presenter
Presentation Notes
One of the things that we heard is that States wanted assistance in creating policies and procedures on use of the Highway Safety Manual. This guidance document, funded by the HSM Implementation Pooled Fund Study, identifies existing language from states, and also provides sample language. This language can provide an agency a place to start from to modify and tweak into polices and procedures that work for their agency. There is language for each PD phase, and the guidance document should be available by October 2016.
Scale and Scope of Safety Assessment Methods in the PDP
• Helps identify appropriate safety assessment methods for various project applications
• Chapter on each PD Phase, with examples• Includes a continuous case study example
(planning through design)• Anticipated completion date: November
2016
Scale and Scope of Safety Assessment Methods in the Project Development Process
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Presenter
Presentation Notes
Another resource funded under the HSM Implementation pooled fund study that will be available soon is the Scale and Scope of Safety Assessment Methods in the Project Development Process. The guide helps identify appropriate safety assessment methods for various project tasks in each phase of the Project Development Process. The guide also provides some very detailed examples which show how to conduct the analysis by hand, using spreadsheets, and the IHSDM software. This document is anticipated to be available in November.
DDSA assistance under EDC-3: 43 States, 130 Requests and counting…
Virgin IslandsSource: FHWA
Presenter
Presentation Notes
Thus far under EDC-3, we’ve assisted 43 States, helping with over 130 requests and counting. If we can be of assistance, don’t hesitate to reach out.
“A game changer in traffic safety”
74http://www.ksl.com/?sid=29580676&nid=
Source: KSL Broadcasting, Salt Lake City, UT,
Presenter
Presentation Notes
As I said, this initiative began under EDC-3 and we’ve seen tremendous progress so far. This happens to be from a “news story” highlighting Utah’s DDSA efforts.
