Texas Intersection Safety Implementation Plan Workshop JUNE 2, - - PowerPoint PPT Presentation

Texas Intersection Safety Implementation Plan Workshop

JUNE 2, 2016

Why Intersection Safety?

• A small part of overall

highway system, but…

• Each year roughly 50% of all

crashes – estimated 3 million – involve intersections

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Texas: 802 Intersection Fatalities (2014)

Why a systemic approach for intersections? Realizing the SHSP Vision and Goals

• The general consensus among

those involved in transportation safety is that further reductions are not only desirable, but feasible.

• BUT…achieving means new tools,

new approaches, new ideas

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Texas SHSP ‐ Intersection

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Texas SHSP ‐ Pedestrians

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Approaches to Saving Lives and Preventing Serious Injuries

Traditional Systemic Comprehensive Policy Culture

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Conventional vs. Systematic

Conventional/Traditional:

• Based on “High‐crash Locations”

– Purely reactive; identified by very high number of crashes at specific intersection – Usually involves application of countermeasures with high CRF values, but also at high cost (e.g., reconstruction or widening) – Usually fewer than 10‐20 per year in a average size state – By itself, negligible impact on reducing statewide fatalities

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Traditional Systemic Comprehensive Policy Culture

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Traditional Systemic Comprehensive Policy Culture

Conventional vs. Systematic

Systematic/Comprehensive

• Reverses the traditional approach, then enhances it

– Start with known effective, low‐cost countermeasures – Install systematically at large number of intersections with both moderate and high crash histories where cost‐effective results are expected – Typically find that 3‐8% of the intersections with any crash history account for 25‐40% of the statewide intersection problem – Substantial reduction of statewide intersection injuries/ fatalities can be realized with this approach (ties directly to SHSP goals) – Plan can be tailored to available resources – Can also include a Corridor/Community 3E component

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Basic Approach for Intersections

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Key: Making Intersections Incrementally Safer

• Increase visibility of intersections and traffic control devices
• Increase awareness of intersections
• Improve the design of intersections to reduce conflicts
• Improve driver comprehension to reduce confusion
• Improve the operations of intersections
• Improve sight distance at intersections
• Improve driver compliance with traffic control devices

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The End Goal

• It is estimated that deploying these countermeasures will cost

$__M and prevent ____ fatalities and serious injuries over a _ year period.

• The projected Benefit‐Cost Ratio is approximately __:1
• With continued observation/evaluation, most successful

treatments to be considered for systemwide policy/standardization

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Recognizing the Systemic Approach

• New Emphasis in MAP‐21:

– “The term ‘systemic safety improvement’ means an improvement that is widely implemented based on high risk roadway features that are correlated with particular crash types, rather than crash frequency.”

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http://safety.fhwa.dot.gov/systemic

*Multiple ISIPs in TX

FAS-INT: Systemic Intersection Safety Plans

DC FLH PR

State considering or pursuing ISIP independent of HSA-FAS Intersection Safety Implementation Plan (ISIP) completed through HSA-FAS

From 2008-Current

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SHSP objective & recent trajectory

• 2015 objective: Reduce KA intersection crashes by 5% (2010)

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 19%  16%

SHSP objective & recent trajectory

• Latest raw data suggest these may be out of sync
• Good opportunity to consider other approaches

(e.g., systemic approach)

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ISIP derivation

• Texas SHSP
• FHWA support, national resources
• TxDOT inputs
• MPO inputs

Texas ISIP

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• Local agency inputs

FHWA ISIP process

Overarching goals of Texas ISIP Project

• 1. Prioritize intersection locations and

countermeasures for near-term implementation

• 2. Strengthen partnerships between TxDOT, MPOs,

local governments, and FHWA

• 3. Identify opportunities for enhancing Texas’s data

systems to allow for more robust systemic analyses in the future

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Basics

• Analysis period:

– January 2010 – December 2014

• Focused on Texas’s 5

largest MPOs:

– San Antonio (AAMPO) – Austin (CAMPO) – El Paso (El Paso MPO) – Houston (H-GAC) – Dallas-Fort Worth (NCTCOG)

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Intersection crashes by severity and year

Year Fatal A B C PDO Unknown Total KA %KA 2010 330 2,672 12,760 24,774 69,033 1,921 111,490 3,002 2.69% 2011 372 2,609 12,275 24,661 65,753 1,994 107,664 2,981 2.77% 2012 428 2,906 13,359 26,086 67,878 1,460 112,117 3,334 2.97% 2013 372 3,133 14,757 27,676 79,813 2,150 127,901 3,505 2.74% 2014 415 3,240 15,502 29,856 91,812 2,431 143,256 3,655 2.55% Subtotal 1,917 14,560 68,653 133,053 374,289 9,956 602,428 16,477 2.74%

For 5 MPOs combined 45

Systemic analysis | concept meets reality

• Data challenges

– No single statewide intersection database – Traffic volume data not widely available for non State- maintained routes

• What is available?

– MPO TAZ shapefiles  area type (rural/urban) – TxDOT RHiNo database  classification of maintaining agency – CRIS database  traffic control type as recorded by the reporting officer – ESRI Street file  node location in GIS

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Distribution of intersections and KA intersection crashes by area type and traffic control

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Most significant

• verrepresentation

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Summary & recommendation for TX ISIP

• KA crashes comprise less than 3% of

crashes but 47% of the costs

• 90% of KA crashes are in urban areas
• Nearly 50/50 split of KA crashes

between State & Local intersections

• Signalized intersections are

significantly overrepresented in terms of proportion of KA crashes

• vs. proportion of intersections

Focus on State & Local Urban Signalized intersections

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Dallas-Fort Worth area | ≥1 KA crash

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Dallas-Fort Worth area | ≥3 KA crashes

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Potential crash thresholds for systemic treatments

Crash Threshold KA Crashes Intersections

• Avg. Per‐Intersection Funding

(assuming $45M funding) Number Percent Number Percent 1 or more KA crash 7,212 100.0% 4,789 100.0% $9,397 2 or more KA crashes 3,797 52.6% 1,374 28.7% $32,751 3 or more KA crashes 2,021 28.0% 486 10.1% $92,593 4 or more KA crashes 1178 16.3% 210 4.4% $214,286

• For example, more than half of the KA intersection crashes could be

addressed by targeting just 29% of the KA intersection crash locations

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Random Intersection Inventory

• Identified 100 urban signalized intersections under State or

local control that had 2 or more KA crashes during study period

• No. of intersections from each region was roughly

proportional to no. of KA crashes by region

• Utilized Google Earth and Streetview

– Maximize information gathered

Random intersections | Statewide (100)

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Roadway attributes

• 19 of every 20 had some form of

lighting fixture

• 15 of every 16 sites were not noted to

be offset and/or skewed

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LT Arrangement by Approach

• Considering approaches from which left turns were

permitted:

– 70% have exclusive LT lanes or – Only 4% have dual LT lanes

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Traffic Control Count

Pedestrian signals 86% Signal head per lane 78% Backplates 54% Automated red light enforcement (cameras) 37% Advance Signal Ahead warning sign 29% Advance street name sign 26% No Turn on Red sign 19% Red light indicator lights 7% Flashing beacons on advance Signal Ahead sign 3% Advance control detection system 2%

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Inventory to Countermeasures

• Knowing the estimated level of countermeasure deployment

allows the plan to estimate additional deployments of low cost countermeasures

• Builds on sources including FHWA, TxDOT, research

Key Systemic Countermeasures

• Stop‐Controlled Intersections

– Basic set of sign and marking improvements – Improve sight distance for speed limits

• Signalized Intersections

– Basic set of sign and marking improvements – Install one signal head per lane – Retime Traffic Signals including change intervals – Protected‐only left turn phases

• Both Stop‐Controlled and Signalized Intersections

– Access management of high volume driveways within 50‐100 feet – Delineate or remove fixed objects at intersections

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Benefits:

• Provides visual benefits during both

daytime and nighttime conditions

• Enhanced signal visibility for aging

and color vision impaired drivers.

• May alert drivers to signals during

periods of power outages when the signals would otherwise be dark.

Backplates with Retroreflective Borders

Low Cost – Big Safety Benefit

Costs range from $35 for adding reflective tape to existing backplates to $56‐110 for replacing the backplates with reflective material already incorporated A 15 percent reduction in all crash types—a crash modification factor (CMF) of 0.85 (2005 study by Sayed et al)

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Straw Man Outline and Packaging of Safety Countermeasures

Desired countermeasure characteristics

• Potential for widespread use
• Potential impact to severe crashes
• Easy deployment
• Low cost
• Favorable benefit-cost ratio

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Straw Man outline

• Represents high-level benefit/cost analysis
• 5-year analysis period is common
• Comprises estimates of key characteristics:

– Crash reduction factor – Current and potential deployment levels – Construction and maintenance costs – Potential no. and economic benefits of crashes prevented – B/C ratio

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Deployment levels

• Existing

– Estimate based on random intersection inventory

• Potential

– Considers existing applications and target crash types – Estimates will be made on applicability where no inventory could be made (e.g., clearance interval adjustment)

• No. of potential installations across focus

intersections will be estimated

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Potential benefits

• In terms of anticipated KA crashes prevented
• Ties back to estimated no. of installations
• Converts crash savings into cost savings (NSC

method)

• Planning-level B/C ratio estimated

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Systemic approach | today & tomorrow

• Current ISIP effort

– Applying systemic principles – Using available data to derive risk factors, drive focus – Initial prioritization zeros in on sites with crash history

• Future ISIP efforts

– Opportunities to collect and share additional data attributes across all public roads? – Having traffic volume and geometric characteristic data would allow better identification of risk factor combos – Prioritization could reach beyond crash intersections to sites having similar combinations of risk factors

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Project next steps

• Complete planning-level B/C analysis
• Refine prioritized list of intersections
• Develop draft ISIP document

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