Kittelson Workshop: Road Safety Audit
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The Portland office of Kittelson & Associates, Inc. hosted an interactive workshop on January 13th, 2011 that covered the following related to Road Safety Audits (RSA): 1) A brief overview of the Federal Highway Administration (FHWA) “Road Safety Audit (RSA) – Guidelines and Checklist”; and 2) A walk through of a recent RSA application - Mt. Hood Highway (US 26) on the western slope between Portland, Oregon and the Mt. Hood recreational facilities (including ski areas during winter season). Hermanus Steyn, from Kittelson, and Sue D’Agnese, from ODOT, facilitated the workshop.
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Kittelson Workshop: Road Safety Audit
- 1. Mt. Hood Highway (Hwy. 26) Camp Creek Campground to Timberline Road (Mile Post 47.19 to 54.23) January 13, 2011 Presented by: Hermanus Steyn, Pr.Eng., P.E. Sue D’Agnese (ODOT Region 1 Traffic Manager) ROAD SAFETY AUDIT Transportation Education Series Portland, Oregon
- 8. When do we conduct RSAs?
- 11. FHWA RSA Process
- 12. RSA Process – Pre-Audit Meeting
- 15. RSA Process – Field Review
- 19. RSA Process – RSA Analysis
- 22. RSA Process – Presentation of Findings
- 25. Mt. Hood Highway RSA Segment (MP 47.19 to 54.23)
- 26. 2000 – 2008 Crashes Total Crashes = 280
- 28. Crashes by Collision Type ANGL – Angle; HEAD – Head-On; REAR – Rear-End; SS-M – Sideswipe-meeting; SS-O – Sideswipe-overtaking; TURN – Turning Movement; PARK – Parking Maneuver; NCOL – Non-collision; BACK – Backing; PED – Pedestrian; FIX – Fixed/Other Object; OTH - Other Crashes primarily fixed-object or rear-end crashes
- 29. Crashes by Day of the Week Crashes occur primarily during the weekends
- 31. Crashes/ADT by Month Crashes occur primarily during the winter months
- 32. Crashes by Surface Condition SNO – Snow; UNK – Unknown Approximately 70% of crashes occur in the presence of ice and snow
- 55. Thank You – Any Questions?
Notas del editor
- This is the definition of a road safety audit from the FHWA website (http://safety.fhwa.dot.gov/rsa). The underlined words are key. We will examine their implications in the next slide.
- “ formal”: The audit is based on a set of procedures outlined in various manuals and guidelines. The procedures involve the eight-step audit process discussed later in this presentation. “ safety performance”: The RSA focuses on road safety. Other aspects of the project, such as its operational performance or various constraints (geometric, financial, etc.) can be considered, but the job of the RSA team is to identify the safety implications of the project and suggest how it could be improved to address safety concerns. “ independent”: The audit team is independent of the project team, and has no previous familiarity with the project. The audit team’s independence assures two things: that there is no potential conflict of interest (for example, auditing a project prepared by others in the same organization), and the project is reviewed with “fresh eyes”. “ audit team”: The RSA team is typically composed of several engineers having general design/operations experience (including previous RSA experience) and specialist experience. Specialists often include a human-factors specialist, and are necessary where a project entails unusual elements (such as at-grade railway crossings or unusual construction techniques), where a project must accommodate a substantial number of users with needs or limitations different from normal motor vehicle traffic (such as pedestrians, truck drivers, or cyclists), or when a road must function under recurrent challenging conditions (such as winter weather or frequent fog). Other participants on the RSA team might include enforcement and emergency-response staff.
- It is also important to note that the RSA team may need to consider the safety performance of the project from the perspective of all road users. The graphic shows a passenger car, pedestrian, pedal cyclist, motorcyclist, and large truck. Ask participants to name other possible road users – they may come up with public safety vehicles (police or fire), maintenance vehicles, older drivers, etc. How do various project elements interact, especially combinations of minimum standards? For example, what are the implications of providing a minimum-radius curve on an approach to an intersection where the minimum stopping sight distance is provided? Can vehicles (especially trucks) safely brake? The RSA team examines connections to existing infrastructure beyond the project limits, and looks at the segment/intersection from the point of view of users entering and exiting it. For example, is new signing adequate for drivers approaching from adjacent road segments (are approaching drivers correctly positioned for turn-only lanes, and is signing consistent with similar facilities upstream and downstream)? An RSA does not simply identify potential problems – it also identifies “potential” solutions. Some questionable elements may be unavoidable in a design, such as where there are constraints (geometric, fiscal, etc.) that limit the project. An RSA can identify possible mitigation measures to address these risks. For example, limited land availability may result in the need to incorporate a horizontal curve having a radius below the minimum design value for anticipated speeds. The RSA can identify potential measures to identify this hazard (appropriate signing) and induce lower approach speeds (narrower lanes or transverse rumble strips), which can be implemented at reasonable expense during construction.
- Standards checks are often done as part of the design process to check for adherence to design standards and guidelines, and document where those standards and guidelines are not met. This kind of standards check is not part of the road safety audit process. Although the RSA team may compare design elements to standards, it is with the intention of identifying combinations of minimum standards with reference to how these minimums may interact to generate a potential hazard. The RSA team has no mandate to change a design they are auditing. RSAs are very frequently conducted at advanced stages in the design process, when design changes would be costly in terms of fees and delays. The RSA team is charged with reviewing a project for its safety implications, and suggesting measures that can be taken to reduce collision risks within the project’s limits.
- RSAs can be done at any stage of a project’s life. For simplicity’s sake, we have grouped them into three categories: The pre-construction (“design stage”) RSA looks at a roadway before it is built, at the planning/feasibility stage or the design (preliminary or detailed design) stage. An RSA at this stage is more proactive – it can identify potential safety issues before they cause collisions. The earlier a pre-construction RSA is conducted, the more potential it has to efficiently remedy possible safety concerns (see next slide). Construction RSAs are work-zone audits to examine temporary traffic management plans associated with construction or other roadworks, and can also be conducted when construction is completed but before the roadway is opened to traffic. The post-construction or operational (“in-service”) RSA looks at a road that is operating. The post-construction audit is reactive – it is usually conducted to address a collision problem.
- Most collisions are attributed (entirely or in part) to human error, such as failure to observe traffic signals, misjudging gaps in crossing traffic, or failure to see a pedestrian. A good road design is one that can anticipate and accommodate common driver errors. This concept is not new – since the 1960’s, the concept of the “forgiving roadside” has been prevalent, and has led to the widespread use of crash attenuators, slip-base or frangible poles, etc. The road safety audit simply applies this concept of a road design that accommodates driver error to the entire project, on the basis that it is easier to design and build safer roads than to modify or improve driver behavior. This is especially the case as the driving population ages, since older drivers need enhanced guidance and are more prone to making errors of judgement.
- Compromises and constraints among the competing interests listed on the previous slide are a normal part of the planning and design process. The design team has the responsibility of integrating these competing interests to arrive at a design that accommodates these interests in as balanced and effective a manner as possible. RSAs, conducted by an audit team that is independent of the design team, inject safety into the mix of competing interests by explicitly and exclusively identifying the safety implications of project decisions. RSAs make sure that safety does not “fall through the cracks”.
- Step 3: Conduct a pre-audit meeting to review project information and drawings. In Step 2, the RSA team was chosen. In this step, the project owner calls a pre-audit meeting (also known as a “start-up meeting”) that is attended by the RSA team, the project team, and the project owner. The pre-audit meeting kicks off the RSA.
- All relevant information should be requested by the RSA team in advance of the pre-audit meeting. The owner or design team can then supply the requested information at the pre-audit meeting, along with explanations. Information would typically include: drawings (for pre-construction and, if available, for post-construction RSAs) background or related reports such as design reports, justification reports, and IHSDM analysis reports design criteria and parameters (such as design speeds, design vehicles, sight distance requirements, clear zone requirements, etc.) collision history, traffic volumes, and signal timing plans (post-construction RSAs) aerial photographs (if available). The photograph shows a pre-audit meeting for a design-stage RSA held in Illinois. Large design drawings and aerial photographs are visible on the table, along with materials prepared for public-consultation meetings (which showed collision history and traffic volumes) set up on easels at the back of the room.
- Project objectives: For a pre-construction RSA, the owner describes the objectives of the road project, including why it is being pursued and the improvements it is expected to accomplish. For both pre-construction and post-construction RSAs, the owner explains why the road safety audit is being conducted on this project. Project design: For pre-construction audits, the design team describes the road design, including: a description of its individual elements the current design stage and anticipated design/construction schedule the constraints and challenges involved in the design. A frank discussion of the constraints and challenges is critical to the success of the RSA. It is crucial that the RSA team understand the trade-offs and compromises are almost always a part of the design process. A knowledge of these constraints promotes the RSA team’s understanding of the project, and helps the RSA team to identify countermeasures that are practical and reasonable (although the RSA team is not restricted from making any comments related to safety). The photograph shows a pre-audit meeting in Illinois at which one of the engineers on the design team (in blue shirt at right) is going through the design. A design team is typically not involved in a post-construction audit. For these RSAs, the road authority describes any design or operational elements of the audited site that generate concern, as well as the constraints and challenges involved at the site (similar to the discussion for a pre-construction RSA). RSA process: The RSA team describes the audit process. The description usually includes a description of the remaining steps of the audit process (Steps 4 through 8), and an indication of the type of issues and mitigation typically addressed at the design/audit stage they are at. For example, the RSA team will make it clear that, at an advanced (detailed) design stage, the alignment will be taken as “given”, and no substantial alignment changes will be considered or suggested to mitigate safety concerns identified in the course of the audit. Similarly, at a preliminary design stage where no signing or marking plans are provided, these issues will not be addressed. In this way, expectations on all sides are well managed. Schedule: All parties agree on the schedule for the remaining steps of the audit (Steps 4 through 8).
- Step 4: Perform field reviews under various conditions. Field reviews (site visits) are conducted by the RSA team during both daytime and night-time conditions. Field reviews are required for both pre-construction and post-construction RSAs. The field reviews are described in the next slides.
- Field reviews should be conducted for both pre-construction and post-construction RSAs. Field reviews for pre-construction RSAs are conducted to observe the ambient conditions in which the new facility will operate. Field reviews for post-construction RSAs are conducted to observe conditions “on the ground” that create safety hazards. In both cases, the audit team should perform a preliminary review of the drawings (pre-construction RSA) or collision history (post-construction RSA) before attending the site, so that they have an understanding of potential issues. Observe road user characteristics: For example, what are typical speeds? What is the typical traffic mix, including heavy vehicles, pedestrians, and cyclists? Does traffic tend to queue at certain times of the day or in certain lanes? Observe surrounding land uses: What are the existing developments contributing traffic to the audit site? Are there any driveways that might affect the planned roadway? Are any pedestrian generators such as transit facilities or schools nearby? What are the typical traffic patterns associated with the adjacent land uses (for example, weekend traffic near a home improvement store)? Observe link points to the adjacent transportation network: For example, are there at-grade railway crossings in the vicinity of the audit site that could delay traffic? Are interchange ramps close to the site? While on site, some of the things to check for include: driveway issues: Do cars turning into and out of driveways interfere with through traffic? Interference will be particularly unwelcome (a) close to an intersection, where driver workload is already high, and (b) on an arterial-class road, where traffic mobility (rather than access to adjacent properties) is the priority. roadside hazards: Roadside hazards include fixed objects, deep and/or steep drainage ditches, or unprotected barrier ends within the roadside clear zone. The bottom example shows rocks immediately beside the roadway in a national park, where wildlife are common. A driver attempting to evade wildlife on the road may collide with the rocks immediately off to the right and left. sight distance obstructions: Sight distance obstructions typically encountered include buildings, trees and other landscaping features, and commercial signs. The bottom example shows rocks (at left) that block the view between drivers exiting the driveway (at the left of the photo) and drivers coming toward the photographer.
- … it is not very apparent, but there is a single lighted “No Left Turn” sign on the far left corner that prohibits my left turn. The “No Left Turn” sign is illuminated only during peak periods. However, many drivers at this intersection did not realize that the left turn was prohibited, since there was only one sign, it was located beneath a secondary signal head (instead of near the overhead primary signal head), and it was oriented at an angle that limited its conspicuousness (at least during daylight hours). As a result, many drivers stopped to make the prohibited left turn, increasing the collision risk. The important point to note is that the effect on visibility of the offset left turn lanes, and the difficulty in seeing the “No Left Turn” sign, would not likely be apparent without a site visit. There is no substitute for getting out of the car and walking the audit site, especially if traffic at the audit site includes (or will include) pedestrians. The audit team can more closely observe roadside and pavement conditions, as well as pedestrians’ perspective. Time spent walking around or observing the audit site also gives greater insight into driver and pedestrian behavior, although the presence of the audit team may influence this behavior.
- peak and off-peak traffic periods: These periods may vary with surrounding land uses or transportation infrastructure. While peak periods typically display issues related to volume and congestion, the off-peak periods can highlight low-volume issues such as speeding. dry and wet weather conditions: Traction and visibility issues arising from poor surface drainage will be apparent on wet roads. day and night conditions: Daytime lighting may generate visibility issues associated with strong shadows under overpass structures. A human-factors review of night-time conditions is highly recommended, and can highlight issues associated with sign reflectivity, inadequate overhead illumination, signal conspicuousness (particularly if signals must compete with distracting background light sources), and intersection layouts that may be confusing under low light conditions. The example shows a roadway during the daytime and at night. There is a far-side entry ramp (to the left at the far side of the overpass) that is somewhat inconspicuous during the day, but is very difficult to see at night. Other examples of issues identified during field reviews for post-construction audits are shown on the following slide.
- Step 5: Conduct the RSA analysis and prepare report of findings. We will discuss RSA analysis and RSA reporting in detail later in this presentation. For now, we will just give an overview of analysis and reporting. The RSA team performs this step. Input from the project team is generally limited to clarifying elements of the project that may be unclear from the drawings, or offering a preliminary response to potential alternatives or mitigation proposed by the RSA team.
- This slide gives an overview of how the audit is conducted. RSA analyses will be discussed in greater detail later in this presentation. workshop setting: The RSA is usually conducted in one or two workshop sessions. All team members attend and review the drawings together. A photo of an audit, showing the workshop setting, is shown. review background reports and design criteria: Before reviewing the drawings, any background reports (project reports, justification reports, IHSDM analysis reports, etc.) are reviewed. For pre-construction RSAs, it is particularly important to review the design criteria for the project, since these criteria specify the standard to which the roadway is designed. systematically review design drawings and/or other information: For pre-construction RSAs , the drawings should be reviewed systematically, examining design features such as road geometry, sight distances, clear zones, drainage, barriers, etc. Fewer of these elements will be available at early-stage pre-construction RSAs. A checklist may be useful for this review. For post-construction RSAs , design drawings will generally not be available. Instead, information such as collision history, signal timing plans, and turning movement counts will be available and should be reviewed along with field-review findings. identify, prioritize, and mitigate safety issues: This is the main focus of the RSA process. From the review of the drawings and other information, safety issues are identified. Safety issues are associated with project features that may contribute to a higher frequency and/or severity of crashes. Safety issues are then prioritized. For each safety concern, a list of possible ways to mitigate the increased crash potential may be generated. These steps (identifying, prioritizing, and mitigating safety issues) are discussed in the next section on “Understanding Risk and Safety”.
- What crash types are likely? Example crash types are rear-end, sideswipe, angle, off-road, and head-on collisions, and collisions involving cyclists and pedestrians. What is the likelihood of crashes? Likelihood is a function of probability (how likely is a design element to cause a crash) and exposure (how many vehicles will travel on the road segment having the risky design element)? For example, poor visibility may be provided for a left-turn movement (high probability), but the left turn may be associated with a very minor street with a low volume (low exposure). Probability and exposure are discussed further in the next slide. How severe are the crashes likely to be? Severity is usually described in terms of fatal, injury, or property-damage-only collisions, with the latter being the least severe. Several factors affect collision severity, including collision type (for example, rear-end collisions are usually less severe than angle collisions), speed (severity usually increases with speed), and user type (pedestrian and cyclist collisions are often severe). For post-construction audits, responses to the last three questions concerning crashes can be quantified on the basis of actual collision history. When looking at collision history, pay particular attention to the time of the crashes (night-time/daytime, peak/off-peak periods, winter/summer, weekend/weekday), crash causes (as coded by the police), and crash location (in intersection, on approaches to the intersection, in particular lanes such as right-turn lane).
- Step 6: Present RSA findings to project owner and project team. The RSA team presents the findings of the audit (safety issues and suggested mitigation) to the project owner and project team. The presentation of findings may be written (RSA report) or verbal (presentation meeting) or both. Usually it is both.
- The audit team issues a final report documenting the results of the RSA. The main contents of the RSA report are: a prioritized listing of the safety issues identified (illustrated with drawings or photographs where possible), suggestions for improvements. The organization of the RSA report, and examples of RSA reports, will be discussed later in this presentation. The report cover shown is for the audit that we will examine as a case study shortly.