Sadly, most of us know someone who has been seriously hurt or killed in a car crash. These crashes affect not only the victims of the crash, but also significantly impact the lives of their families and friends. The number of people who lost their lives on roads in the US in 2021 was 49,939, and that number is rising. Transportation Secretary Pete Buttigieg wrote in the introduction to the National Roadway Safety Strategy, “the status quo is unacceptable, and it is preventable. We know it’s preventable because bold cities in the United States, and countries abroad, have achieved tremendous reductions in roadway deaths.” Other countries have cut their already lower crash rates in half over the past 20 years, and the United States could learn from some of their crash reduction measures.

From the UK to the US

One of those measures that the United States has adapted is the Road Safety Audit (RSA). In the mid-1980s, accident investigation teams in Kent in the UK were concerned that newly designed and built road projects were becoming accident blackspots. They asked to review the engineering designs of all new road projects to remove safety issues before construction. By 1991, the UK Department of Transport made Road Safety Audits mandatory for trunk roads and motorways, and by 1996, Road Safety Audits were recommended for most new projects.

The United States noticed the success of Road Safety Audits in the UK and started performing RSAs in the early 2000s. And just like America adapted rugby into football, the US used the core principals in the UK Road Safety Audits when adapting the audit process in the US. RSAs in the US are different than in the UK, but the intent to improve safety and the independent nature of the audit are the same.

In the UK (and in the US), Road Safety Audits are performed by an engineering team that is separate from the design team. Safety Audits are classified into stages based on the phase of the project. Stage 1 and 2 Audits consist of a desktop review of the preliminary (Stage 1) or detailed (Stage 2) design drawings and a site visit by the engineering team. Stage 3 Audits look at the final design drawings and the newly constructed project. The intended audience is the design team, so reports are kept brief and to the point. There are no verbose paragraphs about the purpose of the report or descriptions of the location, just a list of the potential safety issues and recommended design changes. Safety Audits are performed on most new projects, so this streamlined approach keeps costs low. I once performed a combined Stage 1 & 2 Audit of a new raised Zebra crossing in front of a school in the London Borough of Richmond for the equivalent of $1,500, and that included our travelcards and lunch at pub. Zebra crossings are marked mid-block crosswalks where the markings resemble zebra stripes, like in the Beatle’s Abbey Road album cover. And yes, a half pint or a shandy was sometimes enjoyed by other members of the audit team as part of lunch at the pub, but usually not until we had completed our site visits for the day.

Adapting RSAs to US Standards

Twenty years after RSAs were introduced in the US, it is worth looking at the two types of audits and what we can learn from the different audit approaches. In the US, RSAs are more complex. According to the Federal Highway Administration, an RSA “is a formal safety performance examination of an existing or future road or intersection by an independent, multidisciplinary team.” Although RSAs can be of future projects, they tend to be performed on existing sites. In 2022, Hoyle Tanner performed three RSAs at intersections with stop-controlled side approaches. RSAs are data driven and involve a detailed review of the existing roadway or intersection geometry, speed data and available crash data. Engineers present this information to a multidisciplinary team made up of town officials, law enforcement, first responders, state transportation officials and other stakeholders. This multidisciplinary team brings valuable insight into driver behavior, variable local traffic patterns and the impacts of rain, snow, or different lighting conditions in the study area that might not be evident during a site visit. After the engineering team presents the traffic data, the multidisciplinary team visits the site, identifies safety concerns, and suggests mitigation measures.

RSAs as a Guide

The RSA reports are comprehensive and can be used as a guide to help in a municipality’s decision-making process for selecting, prioritizing, and implementing safety improvements. A risk assessment helps the municipality determine what safety issues they may wish to focus on. The report identifies safety improvements and categorizes them into short-term, medium-term and long-term improvements. Short-term measures may be as simple as removing overgrown vegetation to improve visibility. Long-term improvements are more complex and involve more investment, such as the construction of a roundabout to reduce angle type crashes. RSA reports include preliminary design drawings and cost estimates of mitigation measures, as well as benefit cost analysis which can be used in the application for funding and to further the project. Crashes are assigned a societal cost based on their severity and take into consideration the cost of emergency services provided by first responders, medical services, lost productivity and wages, legal proceedings and fees, damage to property and pain and suffering. For a fatal crash, these costs exceed $15 million, so often the benefit of doing a project in dollars outweighs the cost. The benefit of a potential mitigation measure is determined by using a Crash Modification Factor (CMF) published by the US Department of Transportation. CMFs are multiplicative factors used to calculate the expected number of crashes after the mitigation measure is constructed, and CMF is based on observational safety studies of roadway changes of the same type, such as the addition of a left turn lane.

The number of crashes resulting in fatal or serious injuries is increasing in the United States, and unless we implement methods proven to address safety issues, more people are going to lose family and friends to crashes or be impacted by life changing injuries.  We should be working with safety experts in other countries and other parts of the United States to learn about effective road safety strategies that have been proven to reduce crashes and improve safety for all road users.  RSA’s are just one example of a safety tool we should be utilizing more often.

Hoyle Tanner has worked on multiple RSA projects as well as projects incorporating safety features from abroad including roundabouts and village gateways. Our transportation engineers are experienced and available to help your community. Connect with me for any questions you might have!


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