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From page 1... ... Research Results Digest 299 November 2005 INTRODUCTION Crash or accident reduction factors (CRFs or ARFs) provide a quick way of estimating crash reductions associated with highway safety improvements and are used by many states and local jurisdictions in program planning to decide whether to implement a specific treatment and/or to quickly determine the costs and benefits of selected alternatives. Read the entire page →
From page 2... ... by a TRB Task Force and NCHRP (3) Read the entire page →
From page 3... ... • Combinations of Treatments. Most AMFs are designed for individual treatments. Read the entire page →
From page 4... ... TABLE 1 AMF Knowledge Matrix Intersection Treatments User Level of Predictive Certainty Ongoing/ Priority Medium- Medium- Non- Future Treatment Level High High Low Low Existent Work Install a roundabout 19 ✓ (5) Read the entire page →
From page 5... ... Convert stop-control to yield-control ✓ (31) Install red-light cameras ✓ (25,26) Read the entire page →
From page 6... ... TABLE 1 (Continued) Roadway Segment Treatments User Level of Predictive Certainty Ongoing/ Priority Medium- Medium- Non- Future Treatment Level High High Low Low Existent Work Add edgeline rumble strips 14 ✓14 ✓ (50) Read the entire page →
From page 7... ... Provide signal coordination 7 ✓ (65) Increase pavement friction ✓ (66) Read the entire page →
From page 8... ... definitions used in establishing the LOPC were as follows: • High. The AMF was developed in a rigorous before–after study that incorporated the current best study design and statistical analysis methods. Read the entire page →
From page 9... ... Ongoing/Future Work The existence of ongoing or planned research that might improve the AMF was determined by a review of several research-in-progress databases, discussions with other highway safety researchers, and conversations with research sponsors such as FHWA and the Insurance Institute for Highway Safety (IIHS) Read the entire page →
From page 10... ... TABLE 3 Summaries of Research Studies That Developed AMFs TREATMENT: Install Roundabout AMF Level of Predictive Certainty: High METHODOLOGY: Empirical Bayes Before-After REFERENCE: Persaud, Retting, Garder, and Lord - 2001 (5) STUDY SITES: • Treatment sites included 23 intersections that were converted between 1992 and 1997 to roundabouts (19 were previously controlled by stop signs, and 4 were controlled by signals) Read the entire page →
From page 11... ... CRASH TYPE STUDIED AND ESTIMATED EFFECTS No. of AMF Total Intersection Accidents Improved One Both (all severity levels, all accident types) Read the entire page →
From page 12... ... TABLE 3 (Continued) TREATMENT: Add Exclusive Right-Turn Lane AMF Level of Predictive Certainty: High CRASH TYPE STUDIED AND ESTIMATED EFFECTS No. Read the entire page →
From page 13... ... TABLE 3 (Continued) TREATMENT: Install a Traffic Signal AMF Level of Predictive Certainty: High CRASH TYPE STUDIED AND ESTIMATED EFFECTS No. Read the entire page →
From page 14... ... TABLE 3 (Continued) TREATMENT: Remove a Traffic Signal AMF Level of Predictive Certainty: High CRASH TYPE STUDIED AND ESTIMATED EFFECTS No. Read the entire page →
From page 15... ... TABLE 3 (Continued) TREATMENT: Modify Signal Change Interval AMF Level of Predictive Certainty: Medium-High CRASH TYPE STUDIED AND ESTIMATED EFFECTS No. Read the entire page →
From page 16... ... TABLE 3 (Continued) TREATMENT: Convert to All-Way Stop Control AMF Level of Predictive Certainty: Medium-High CRASH TYPE STUDIED AND ESTIMATED EFFECTS No. Read the entire page →
From page 17... ... TABLE 3 (Continued) TREATMENT: Convert Stop-Control to Yield-Control AMF Level of Predictive Certainty: Medium-High CRASH TYPE STUDIED AND ESTIMATED EFFECTS No. Read the entire page →
From page 18... ... TABLE 3 (Continued) TREATMENT: Install Red-Light Cameras AMF Level of Predictive Certainty: High CRASH TYPE STUDIED AND ESTIMATED EFFECTS No. Read the entire page →
From page 19... ... TABLE 3 (Continued) TREATMENT: Narrow Lane Widths to Add Lanes AMF Level of Predictive Certainty: Medium-High CRASH TYPE STUDIED AND ESTIMATED EFFECTS No. Read the entire page →
From page 20... ... METHODOLOGY: Analysis-Driven Expert Panel REFERENCE: Harwood, Council, Hauer, Hughes, & Vogt - 2000 (7) COMMENTS: • Expert panel considered these AMFs to be the best estimates for the installation of passing lanes on rural two-lane roadways. Read the entire page →
From page 21... ... METHODOLOGY: Analysis-Driven Expert Panel REFERENCES: Harwood, Council, Hauer, Hughes, & Vogt - 2000 (7) and Harwood, Rabbani, Richard, McGee, & Gittings - 2003 (70) Read the entire page →
From page 22... ... METHODOLOGY: Analysis-Driven Expert Panel REFERENCES: Harwood, Council, Hauer, Hughes, & Vogt - 2000 (7) and Harwood, Rabbani, Richard, McGee, & Gittings - 2003 (70) Read the entire page →
From page 23... ... METHODOLOGY: Analysis-Driven Expert Panel REFERENCE: Harwood, Council, Hauer, Hughes, & Vogt - 2000 (7) COMMENTS: • AMF applies to total accidents on the curved roadway segment. Read the entire page →
From page 24... ... METHODOLOGY: Before-After with Comparison Sites REFERENCE: Griffith - 1999 (47) STUDY SITES: • Included 55 treatment sites and 55 matched comparison sites from rural and urban freeways in Illinois. Read the entire page →
From page 25... ... METHODOLOGY: Empirical Bayes Before-After REFERENCE: Persaud, Retting, & Lyon - 2003 (51) STUDY SITES: • Crash and traffic volume data were collected for 98 treatment sites, consisting of 210 miles, where centerline rumble strips had been installed on rural two-lane roads in the states of California, Colorado, Delaware, Maryland, Minnesota, Oregon, and Washington. Read the entire page →
From page 26... ... METHODOLOGY: Meta-analysis REFERENCE: Elvik and Vaa - 2004 (55) STUDY SITES: • 20 studies were evaluated, including 12 U.S. Read the entire page →
From page 27... ... of this study. One of these studies is NCHRP Project 17-27, Parts I and II of the Highway Safety Manual (HSM) Read the entire page →
From page 28... ... Publication FHWA-RD-99-207. Read the entire page →
From page 29... ... 30. Lovell, J Read the entire page →
From page 30... ... 52. Bligh, R Read the entire page →
From page 31... ... 75. Hauer, E Read the entire page →
From page 32... ... Transportation Research Board 500 Fifth Street, NW Washington, DC 20001 These digests are issued in order to increase awareness of research results emanating from projects in the Cooperative Research Programs (CRP) Read the entire page →

From page 1...

... Research Results Digest 299 November 2005 INTRODUCTION Crash or accident reduction factors (CRFs or ARFs) provide a quick way of estimating crash reductions associated with highway safety improvements and are used by many states and local jurisdictions in program planning to decide whether to implement a specific treatment and/or to quickly determine the costs and benefits of selected alternatives.