The National Academies Press

Currently Skimming:

Pages 1-28

The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.

From page 1... ... This thought process led to an expectation that if the total number of crashes at a given location was reduced due to some mitigative action, some fraction of fatal crashes would also be reduced. In support of this approach to safety planning, safety programs were focused on identifying and addressing locations with large numbers of crashes, and a great deal of effort went toward developing techniques and models to assist analysts to more accurately identify those locations where the large number of crashes was also greater than what would be expected. Read the entire page →
From page 2... ... National crash statistics overwhelmingly suggest that to improve the effectiveness of safety programs, states need new partners in a more comprehensive approach to safety. State safety programs need to address all road systems and more actively engage local road authorities in the statewide safety planning process -- state systems may carry the bulk of the vehicle miles travelled, but local systems account for as much as 90% of total road miles and 60% of fatal crashes. Read the entire page →
From page 3... ... The objective of black spot analysis is to find locations that exhibit unusually high crash frequencies or crash rates. The crash data are then analyzed and problem locations are prioritized and ranked. Read the entire page →
From page 4... ... A number of states have indicated that they expect this approach to be more effective for reducing these types of widely distributed severe crashes. LOCATION OF SEVERE CRASHES -- RURAL VERSUS URBAN AND STATE VERSUS LOCAL A closer look at where severe crashes occur provides further support for including systematic approaches in highway safety programs. Read the entire page →
From page 5... ... 5Table 1 Rural versus urban highway fatalities Location Rural Urban Unknown Total State Number Percent Number Percent Number Percent Number Alabama 726 65 380 34 4 <1 1,110 Alaska 44 54 38 46 0 0 82 Arizona 516 48 555 52 0 0 1,071 Arkansas 496 76 153 24 0 0 649 California 1,496 37 2,499 63 0 0 3,995 Colorado 316 57 238 43 0 0 554 Connecticut 47 16 249 84 0 0 296 Delaware 71 61 46 39 0 0 117 District of Columbia 0 0 44 100 0 0 44 Florida 1,257 39 1,942 60 14 <1 3,213 Georgia 836 51 737 45 68 4 1,641 Hawaii 64 46 74 54 0 0 138 Idaho 202 80 50 20 0 0 252 Illinois 501 40 747 60 0 0 1,248 Indiana 569 63 329 37 0 0 898 Iowa 357 80 89 20 0 0 446 Kansas 326 78 90 22 0 0 416 Kentucky 677 78 187 22 0 0 864 Louisiana 520 52 473 48 0 0 993 Maine 164 90 19 10 0 0 183 Maryland 245 40 369 60 0 0 614 Massachusetts 36 8 398 92 0 0 434 Michigan 642 59 445 41 0 0 1,087 Minnesota 352 69 158 31 0 0 510 Mississippi 629 71 255 29 0 0 884 Missouri 686 69 306 31 0 0 992 Montana 263 95 14 5 0 0 277 Nebraska 205 80 51 20 0 0 256 Nevada 122 33 248 66 3 1 373 New Hampshire 105 81 24 19 0 0 129 New Jersey 119 16 605 84 0 0 724 New Mexico 302 73 111 27 0 0 413 New York 672 50 660 50 0 0 1,332 North Carolina 1,226 73 450 27 0 0 1,676 North Dakota 103 93 8 7 0 0 111 Ohio 815 65 440 35 0 0 1,255 Oklahoma 540 70 226 30 0 0 766 Oregon 342 75 113 25 0 0 455 Pennsylvania 765 51 726 49 0 0 1,491 Rhode Island 8 12 61 88 0 0 69 South Carolina 966 90 111 10 0 0 1,077 South Dakota 127 87 19 13 0 0 146 Tennessee 699 58 512 42 0 0 1,211 Texas 1,894 55 1,565 45 7 <1 3,466 Utah 189 63 110 37 0 0 299 Vermont 63 95 3 5 0 0 66 Virginia 612 60 414 40 1 <1 1,027 Washington 353 62 218 38 0 0 571 West Virginia 363 84 69 16 0 0 432 Wisconsin 502 66 254 34 0 0 756 Wyoming 124 83 26 17 0 0 150 U.S. Total 23,254 56 17,908 43 97 <1 41,259 SOURCE: 2007 data from the Fatal Analysis Reporting System (FARS) Read the entire page →
From page 6... ... 6Table 2 Fatal crashes by jurisdiction (highways managed by a state transportation agency versus highways managed by local agencies) Jurisdiction State Agency Local Agency Unknown State Number Percent Number Percent Number Percent Total Alabama 623 56 486 44 1 <1 1,110 Alaska 38 46 41 50 3 4 82 Arizona 462 43 549 51 60 6 1,071 Arkansas 515 79 134 21 0 0 649 California 1,718 43 2,276 57 1 <1 3,995 Colorado 357 64 197 36 0 0 554 Connecticut 212 72 84 28 0 0 296 Delaware 73 62 44 38 0 0 117 District of Columbia 4 9 40 91 0 0 44 Florida 1,956 61 1,242 39 15 <1 3,213 Georgia 1,010 62 627 38 4 <1 1,641 Hawaii 83 60 51 37 4 3 138 Idaho 148 59 104 41 0 0 252 Illinois 761 61 487 39 0 0 1,248 Indiana 497 55 401 45 0 0 898 Iowa 210 47 236 53 0 0 446 Kansas 242 58 174 42 0 0 416 Kentucky 743 86 121 14 0 0 864 Louisiana 803 81 190 19 0 0 993 Maine 117 64 66 36 0 0 183 Maryland 438 71 175 29 1 <1 614 Massachusetts 222 51 212 49 0 0 434 Michigan 432 40 655 60 0 0 1,087 Minnesota 267 52 243 48 0 0 510 Mississippi 497 56 387 44 0 0 884 Missouri 759 77 233 23 0 0 992 Montana 212 77 65 23 0 0 277 Nebraska 137 54 119 46 0 0 256 Nevada 147 39 211 57 15 4 373 New Hampshire 78 60 51 40 0 0 129 New Jersey 330 46 394 54 0 0 724 New Mexico 251 61 155 38 7 2 413 New York 601 45 731 55 0 0 1,332 North Carolina 777 46 899 54 0 0 1,676 North Dakota 57 51 54 49 0 0 111 Ohio 668 53 587 47 0 0 1,255 Oklahoma 526 69 240 31 0 0 766 Oregon 233 51 222 49 0 0 455 Pennsylvania 1,215 81 276 19 0 0 1,491 Rhode Island 36 52 33 48 0 0 69 South Carolina 593 55 481 45 3 <1 1,077 South Dakota 83 57 63 43 0 0 146 Tennessee 807 67 404 33 0 0 1,211 Texas 1,654 48 1,811 52 1 <1 3,466 Utah 205 69 94 31 0 0 299 Vermont 38 58 28 42 0 0 66 Virginia 630 61 396 39 1 <1 1,027 Washington 275 48 294 51 2 <1 571 West Virginia 302 70 130 30 0 0 432 Wisconsin 354 47 402 53 0 0 756 Wyoming 118 79 32 21 0 0 150 U.S. Read the entire page →
From page 7... ... 6. Has the level of safety improvement funding in your state allocated through black spot analysis and through systematic improvements changed in recent years? Read the entire page →
From page 8... ... In many cases, the districts submit candidate locations or projects for safety funding that are then reviewed, prioritized, and approved by safety staff or committees at the agency's 0 50 100 150 200 Ark an sa s Ca lifo rni a Co lor ad o Ha wa ii Iow a Ka ns as Ke ntu cky Lo uis ian a Ma ssa ch us ett s Mi ch iga n Mi nn es ota Mi sso uri Mo nta na Ne w H am ps hir e Ne w M ex ico Ne w Y ork No rth Ca rol ina No rth Da ko ta Or eg on Pe nn syl va nia So uth Ca rol ina So uth Da kot a Te nn es se e Ve rm on t Vir gin ia $ M illi on Figure 5 Safety improvement budgets of the 25 responding states. Read the entire page →
From page 9... ... • The effectiveness of certain systemwide strategies for reducing severe road-departure crashes such as shoulder rumble strips and cable median barriers. • Increased weighting of fatal and serious-injury crashes, which has lowered the priority of some intersection black spots. Read the entire page →
From page 10... ... Iowa Case Study Black Spot versus Systematic Methods Iowa reported an approach that combines systematic and black spot methods in terms of allocating HSIP funds. The high-priority strategies, which are rural road edges and cable median barriers, were selected through a systemwide analysis. Read the entire page →
From page 11... ... Minnesota Case Study Black Spot versus Systematic Methods Minnesota reported an approach with HSIP funds that is predominantly based on black spots in the Minneapolis/St. Paul metropolitan area, where crash densities are higher, and predominantly systematic in the rest of the state, where crash densities are lower. Read the entire page →
From page 12... ... HSIP Approach: Strengths, Weaknesses, and Potential Improvements The strengths of the current HSIP approach were identified as the following: • Local system participation -- dedicating safety funds for projects on the local system of highways. Local highways have almost as many fatal crashes as rural state highways and a 30% higher fatal crash rate. Read the entire page →
From page 13... ... Missouri Case Study Black Spot versus Systematic Methods Missouri reported that 75% of HSIP funds had historically been directed toward black spots -- primarily intersections with a history of severe crashes. However, since 2007, the focus has shifted to a more systematic approach, and almost two-thirds of HSIP funding has been directed toward systemwide solutions, including shoulder improvements and edge line rumble strips on major roads. Read the entire page →
From page 14... ... • MoDOT expects the HSIP to continue to transition toward a more proactive, systematic approach as a result of the new focus on severe crashes and road-departure crashes. North Carolina Case Study Black Spot versus Systematic Methods North Carolina reported an HSIP approach that is predominantly black spot focused -- approximately 90% of the program. Read the entire page →
From page 15... ... Most of the systematic efforts are countermeasure specific, such as median barriers, rumble strips on freeways, safety edges, clearance intervals, removal of late night flash for signals, and so forth. In terms of driver behavior, the North Carolina Governor's Highway Safety Program has developed and manages grant-based behavioral safety programs including seat belt and child safety seat usage programs, alcohol programs, and speed enforcement programs. Read the entire page →
From page 16... ... However, the participating states acknowledged that the adoption of severe crashes as the safety performance measure has had the most profound effect on their safety programs. Finding a Balance -- Black Spot versus Systematic Methods The participating states indicated that prior to SAFETEA-LU their safety programs had been almost exclusively focused on finding and then Read the entire page →
From page 17... ... The national statistics are very clear: well over one-half of fatal crashes are in rural areas, and approximately one-half of these are on the local system -- locations with little or no history of safety investment because for all practical purposes there are no black spots. The states recognize that the historic approach of reacting to black spots cannot be entirely effective given the new safety performance measure because most severe crashes are randomly distributed across thousands of miles of rural roads and at tens of thousands of rural intersections, where there is no history of previous severe crashes. Read the entire page →
From page 18... ... The Iowa DOT also provides training for local engineers through an annual safety workshop, and it directs about 70% of a separate state-funded safety program to projects developed by local agencies for implementation on local roads. The 70% of the state safety funds directed to local projects amounts to approximately 18% of all safety expenditures. Read the entire page →
From page 19... ... This new approach has directed more than 60% of HSIP funds to Mn/DOT's rural districts, and almost 50% of the safety funds are reserved for projects developed by local agencies for implementation on local roads. In addition to noting the lessons they have learned, the states indicated some challenges that will have to be addressed before inclusion of local road authorities in the safety planning process becomes routine. Read the entire page →
From page 20... ... The countermeasures selection tool is integrated with the diagnosis tool and presents users with a suggested set of countermeasures for further consideration. The economic appraisal tool is used to assess the economic viability of each of the countermeasures, using four economic appraisal methods. Read the entire page →
From page 21... ... The primary objective of the project is to develop a safety performance function for low-volume rural county highways and a new statistical model. The new model would then be incorporated into the Iowa Traffic Safety Data Service, which provides technical assistance to county highway agencies, including preparation of maps and lists of at-risk locations and recommendations of potential safety improvement projects.7 Texas The Texas Transportation Institute at Texas A&M University studied horizontal curves along Texas's farm-to-market road system.8 These curves were selected based on identification as at-risk locations that don't regularly show up using traditional "hot-spot" techniques. Read the entire page →
From page 22... ... A methodology based on this curve radius–crash rate relationship was applied and refined as part of the preparation of a Countywide Safety Plan for Olmsted County, Minnesota. One of the key results of a data-driven analysis process was the finding that road-departure crashes on horizontal curves were overrepresented -- 40% of severe road-departure crashes occurred on curves, even though curves made up only 15% of rural county highway mileage. Read the entire page →
From page 23... ... Due to their historic lack of involvement in statewide safety planning, county highway departments have little or no experience with safety analysis, the safety planning process, the competitive funding process, or the development of safety projects. Mn/DOT found that even after it opened its safety program to the counties and dedicated almost one-half of HSIP funds to local system projects, many county engineers were reluctant to participate, and few of the projects submitted by the counties were consistent with the priorities established in the SHSP. Read the entire page →
From page 24... ... K A B C PDO K A 7 CSAH 3 Mower Co - CSAH 6 1 295 1 0 0 0 0 1 0 800 1,250 Yes xxx 6 3,075 1 0 1 1 1 1 0 1,150 1,875 Yes xxx 3 1,150 0 0 1,150 1,050 Yes Yes xxxx 2 1,500 0 0 900 725 Yes Yes xxxx 4 3,200 0 0 1,050 1,500 Yes Yes xxx 6 1,600 0 0 1 0 0 0 0 800 1,100 Yes xxx 9 1,200 0 1 0 0 0 0 0 800 500 xxx 2 3,650 0 1 0 2 0 0 1 1,000 725 Yes xxx 5 2,150 0 0 1 0 0 0 0 1,100 1,025 Yes xxx 6 2,150 0 0 0 0 1 0 0 1,150 325 Yes xxx 3 2,100 0 0 1,850 800 Yes Yes xxx 5 1,000 0 1 0 0 2 0 1 850 1,350 Yes Yes xxxxx 6 1,150 0 0 850 1,250 Yes Yes xxxx 1 1,250 0 0 1 0 0 0 0 850 1,225 Yes Yes xxxx 2 1,250 0 0 800 1,250 Yes Yes xxxx 4 480 0 0 800 1,250 Yes Yes xxx 1 1,900 0 0 2 0 0 0 0 1,050 975 Yes xxx 3 1,900 0 0 1 0 0 0 0 1,150 1,075 Yes Yes xxxx 4 295 0 0 800 1,250 Yes Yes xxx 5 295 0 0 800 1,200 Yes Yes xxx 3 350 0 2 0 0 0 0 1 1,000 375 Yes xxx 3 400 0 0 850 1,275 Yes Yes xxx 4 1,200 0 0 0 1 0 0 4 -MnCMAT crash data, 2003-2007 -Curve #'s are based on the West to East and South to North road direction. 3 611 24 15 101 47 0 1,300 600 Yes Yes xxx None None None None None 63 CSAH 25 CSAH 3 - CSAH 22 64 CSAH 23 CSAH 19 - TH 42 65 CR 143 CSAH 11 - CSAH 19 CSAH 12 - Wabasha Co 71 CSAH 16 CSAH 1 - US 52 75 CSAH 18 52 CSAH 10 Chatfield City Limits - I-90 None 44 CSAH 6 CSAH 3 - US 63 41 CSAH 34 US 14 - CSAH 3 42 CSAH 3 CSAH 6 - CSAH 4 26 CSAH 5 Byron City Limits - Dodge Co (CSAH 17) Read the entire page →
From page 25... ... However, a number of states said that they face a challenge beyond deciding whether or not to provide local authorities with crash data and technical assistance related to safety planning or extending HSIP funds to projects on the local system. This challenge is the lack of technical staff at local agencies. Read the entire page →
From page 26... ... Over the past several years, MoDOT has undertaken extensive renovation of its high-volume roads and has added safety features including more than 500 miles of cable median barriers to the Interstate routes and 6-in. edge lines, paved shoulders, and center and edge line rumble strips to two-lane rural roads. Read the entire page →
From page 27... ... Severe crashes are scatted across tens of thousands of miles of rural highways and thousands of rural intersections, but techniques for identifying the most at-risk locations are not as mature as the techniques for finding black spots. Second, even if states increase their level of engagement with local road authorities, concerns remain about lack of safety planning experience, especially in counties that manage the rural secondary system, where approximately onehalf of fatal crashes occur. Read the entire page →
From page 28... ... 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...

... This thought process led to an expectation that if the total number of crashes at a given location was reduced due to some mitigative action, some fraction of fatal crashes would also be reduced. In support of this approach to safety planning, safety programs were focused on identifying and addressing locations with large numbers of crashes, and a great deal of effort went toward developing techniques and models to assist analysts to more accurately identify those locations where the large number of crashes was also greater than what would be expected.