Highway Safety Manual DAY 2 - HSM Practitioners Guide for Multilane Rural Highways and Urban Suburban Streets Cover Slide for the one-day NHI format 2010 AASHTO Highway Safety Manual Practitioners Guide for Multilane Rural Highways and Urban Suburban Streets workshop. This one-day workshop is the former NHI 380070B course which has been updated to the final version 4.0 Highway Safety Manual as published by AASHTO in June of 2010. Workshop participants are provided the technical information of Chapters 11 and 12 and examples of how to apply this technical information and will be able to use the tools of the Highway Safety Manual effectively upon completion of this workshop. Workshop includes exercises as adult learning activity to apply the technical information of the Highway Safety Manual to real world locations.

Review from DAY 1 Session #1 – Introduction and Background for HSM Rural Multilane and Suburban Urban Streets Length of Session 01 is 35 minutes which means that the instructor needs to move this session right along and not take up too much time with introduction and issue identification.

Introduction and Background HSM Applications to Multilane Rural Highways and Urban Suburban Streets Introduction and Background - Session #1 Session #1 – Introduction and Background for HSM Rural Multilane and Suburban Urban Streets Length of Session 01 is 35 minutes which means that the instructor needs to move this session right along and not take up too much time with introduction and issue identification.

HSM Applications to Multilane Rural Highways and Urban Suburban Streets Learning Outcomes: Review Crash Frequency Performance of Rural Multilane Segments and Intersections Learning Outcomes for Session #1 Introduction and Background

HSM Practitioner's Guide for Two-Lane Rural Highways August 2010 HIGHWAY SAFETY MANUAL Multilane Rural Highways and Urban Suburban Streets 1.1. Purpose and Intended Audience: The Highway Safety Manual (HSM) provides analytical tools and techniques for quantifying the potential effects on crashes as a result of decisions made in planning, design, operations, and maintenance. There is no such thing as absolute safety. There is risk in all highway transportation. A universal objective is to reduce the number and severity of crashes within the limits of available resources, science, and technology, while meeting legislatively mandated priorities. The information in the HSM is provided to assist agencies in their effort to integrate safety into their decision-making processes. Specifically, the HSM is written for practitioners at the state, county, metropolitan planning organization (MPO), or local level. The HSM’s intended users have an understanding of the transportation safety field through experience, education, or both. This knowledge base includes: ■■ ■Familiarity with the general principles and practice of transportation safety; ■■ ■Familiarity with basic statistical procedures and interpretation of results; and ■■ ■Suitable competence to exercise sound traffic safety and operational engineering judgment. The users and professionals described above include, but are not limited to, transportation planners, highway designers, traffic engineers, and other transportation professionals who make discretionary road planning, design, and operational decisions. The HSM is intended to be a resource document that is used nationwide to help transportation professionals conduct safety analyses in a technically sound and consistent manner, thereby improving decisions made based on safety performance. Documentation used, developed, compiled, or collected for analyses conducted in connection with the HSM may be protected under Federal law (23 USC 409). The HSM is neither intended to be, nor does it establish, a legal standard of care for users or professionals as to the information contained herein. No standard of conduct or any duty toward the public or any person shall be created or imposed by the publication and use or nonuse of the HSM. The HSM does not supersede publications such as the U.S. DOT FHWA’s Manual on Uniform Traffic Control Devices (MUTCD), Association of American State Highway Transportation Officials’ (AASHTO’s) “Green Book” titled A Policy on Geometric Design of Highways and Streets, or other AASHTO and agency guidelines, manuals, and policies. If conflicts arise between these publications and the HSM, the previously established publications should be given the weight they would otherwise be entitled if in accordance with sound engineering judgment. The HSM may provide needed justification for an exception from previously established publications.

Multilane Highways - Expressways: Safety and Operational Effects of Geometric Design Features for Multilane Rural Highways Workshop April 2009 Multilane Highways - Expressways: Constructed since the early 1950’s Expressways are less expensive to build no grade separation Intersections (less $$) not full access control (less $$) Instructor: From October 2006 for 2005 US public roads inventory report Session 1 – Introduction and Background

Multilane Highways (Rural&Urban): Safety and Operational Effects of Geometric Design Features for Multilane Rural Highways Workshop April 2009 Multilane Highways (Rural&Urban): 3,995,644 miles – US Public Roads 976,477 miles - US Federal Aid Mileage 165,783 miles - Multilane Highways 17% 44,673 miles – Multilane Undivided 27% 121,100 miles – Multilane Divided 73% 65,357 miles - Multilane rural highways Instructor: From October 2006 for 2005 US public roads inventory report Session 1 – Introduction and Background

Rural Expressway Mileage: Safety and Operational Effects of Geometric Design Features for Multilane Rural Highways Workshop April 2009 Rural Expressway Mileage: From NCHRP 650, Table 1 published Sept 2010 Dr. Tom Mays *NCHRP 650 Session 1 – Introduction and Background

Safety Performance of Rural Multilane Highways: Safety and Operational Effects of Geometric Design Features for Multilane Rural Highways Workshop April 2009 Safety Performance of Rural Multilane Highways: Crash rate on rural expressways (0.9 crashes per mvm) less than for rural 2-lane Highways (1.0 crashes per mvm) Severities on rural expressways (1.2 deaths per 100 mvm) less than for rural 2-lane Highways (1.5 deaths per 100 mvm) When access density is low, crash rate is similar to rural freeway (0.52 per mvm) Instructor: From NCHRP 650 – results are by Minn Dot * Minn DOT, NCHRP 650 Session 1 – Introduction and Background

Example from nchrp 650 of crash rates Safety and Operational Effects of Geometric Design Features for Multilane Rural Highways Workshop April 2009 Instructor: Example from nchrp 650 of crash rates Please note that the crash rates (crashes/million vehicle miles) for 4-lane rural divided expressways are significantly lower for fatal and somewhat lower for injury and actually more than rates for 2-lane hwys planned for conversion to 4-lane divided. Session 1 – Introduction and Background

Approaches for Considering Safety 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 Instructor: Nominal Safety literally means “Safety” in name only This was the traditional way of presenting the “safety” associated with geometric values presented in the AASHTO Green Book and in the state design standards and in the national MUTCD. That is, for a certain width of traffic lane or shoulder, meeting that value had the meaning of being a “safe” design which is far too simplistic a way to think of safety performance. There are many roads that have lane width and shoulders less than the minimum values of the green book that have fewer crashes than the average. See the 3rd paragraph of the forward of the Green Book Substantive safety is the actual crash frequency and severity of a highway or intersection. Substantive Safety performance and philosophy were created by Esira Hauer in the mid 1990’s; the Substantive Safety philosoply has been embraced by AASHTO and is a tenant of the practice of professional transportation today. *Ezra Hauer, ITE Traffic Safety Toolbox Introduction, 1999

Substantive Safety is a Continuum HSM Practitioner's Guide for Two-Lane Rural Highways Substantive Safety is a Continuum August 2010 Which model more closely describes what stakeholders are thinking? Key Message: Substantive safety is not a yes/no or black/white thing (as is nominal safety). Rather, it is a continuum that is often non-linear. Thus, a slight degradation in stopping sight distance (or alternatively, a slightly sharper curve, or narrower shoulder, etc.) should not be expected to produce a significantly different performance in terms of crashes. Additional Info: This is a very important insight. Note that at some point on the continuum, as a design value or other feature degrades, one should expect the safety consequences to begin to be seen. There is not a large body of work that is available to support just where on the continuum safety problems will begin to develop. Two lane rural roads are fairly well defined, other facilities not as much. If you only apply nominal safety, your discussions with stakeholders will only center on safe vs. unsafe. In actuality, most design values follow a continuum of safety where changes in design values may represent only a slight increase in safety risk. In discussing safety tradeoffs, stakeholders are thinking orange line while engineers look at the blue line. Question/Interactivity: The instructor should use this graphic to point out where design criteria typically reside in the continuum (well to the right). Reference:

Nominal and Substantive Safety Safety and Operational Effects of Geometric Design Features for Multilane Rural Highways Workshop April 2009 Example: 1st Step 2nd Step Nominal Safety: Rural Multilane intersection design has median opening (CMF = 1.00) Substantive Safety Use Positive Offset alignment Left Turning Lanes CMF = 0.52 which is 48% fewer total crashes Instructor: No left turn lane in a multilane rural highway is the base condition for rural multilane highway intersections. CMF2i—Intersection Left-Turn Lanes The SPF base condition for intersection left-turn lanes is the absence of left-turn lanes on all of the intersection approaches. The CMFs for presence of left-turn lanes are presented in Table 11-22 for total crashes and injury crashes. These CMFs apply only on uncontrolled major-road approaches to stop-controlled intersections. The CMFs for installation of left-turn lanes on multiple approaches to an intersection are equal to the corresponding CMF for installation of a left-turn lane on one approach raised to a power equal to the number of approaches with left-turn lanes (i.e., the CMFs are multiplicative, and Equation 3-7 can be used). There is no indication of any effect of providing a left-turn lane on an approach controlled by a stop sign, so the presence of a left-turn lane on a stop-controlled approach is not considered in applying Table 11-22. The CMFs for installation of left-turn lanes are based on research by Harwood et al. (4) and are consistent with the CMFs presented in Chapter 14, Intersections. A CMF of 1.00 is used when no left-turn lanes are present. table 11-22. Crash Modification Factors (CMF2i) for Installation of Left-Turn Lanes on Intersection Approaches Intersection Type Crash Severity Level Number of Non-Stop-Controlled Approaches with Left-Turn Lanesa One Approach Two Approaches Three-leg minor-road stop controlb Total 0.56 — Fatal and Injury 0.45 — Four-leg minor-road stop control Total 0.72 0.52 Fatal and Injury 0.65 0.42 a Stop-controlled approaches are not considered in determining the number of approaches with left-turn lanes b Stop signs present on minor-road approaches only. Session 1 – Introduction and Background

Nominal and Substantive Safety Signalized Intersections: A Guidebook Workshop Nominal and Substantive Safety May 2006 Example: At 20,000 ADT 2nd Step 1st Step Example of Nominal requirements and Substantive Safety Where there are substantive safety shortfalls, Enhance Application of Traffic Control Devices, such as signal head per lane centered over the lane Per table 100 of sig 26.3 crashes/mile 4.2 crashes/mile Nominal Safety – Two 12’ wide lanes in each direction +Add median = Substantive Safety Session 1 – Introduction and Background

HSM Applications to Multilane Rural Highways and Urban Suburban Streets Learning Outcomes: Reviewed Crash Frequency (Safety) Performance of Rural Multilane Intersections Defined Substantive Safety beyond Nominal Safety Instructor: review the learning outcomes for this module with the participants going over what they have learned.

Questions and Discussion: Introduction and Background Questions and Discussion: