How computer modeling helps discover the details of vehicle accidents

By Zak Sonntag | [email protected]

Detectives are investigating the fatal motor vehicle accident involving 22-year-old Santiago Lobato, who drifted into oncoming traffic before overcorrecting and rolling his vehicle at 5300 South and Holladay Boulevard in Holladay on Feb. 5.

“The vehicle essentially vaulted off a concrete-and-stone mailbox and went airborne,” and the driver was partially ejected from the vehicle, said detective Matt Masock, speaking with the City Journals.

Masock is a collision expert who works with the Collision Analysis Reconstruction (CAR) Unit, a special operations team that uses sophisticated technology and computer modeling to re-create the conditions of accidents in an effort to determine causes and factors.

“If there is a fatality or near fatality, our CAR unit gets involved and we delve into the how of the accident. We get more in depth and go to a bigger extent than typical crashes, because the consequences are higher and it’s critical that we determine the problems in serious accidents,” said Masock, who’s heading the reconstruction investigation for the Feb. 5 accident.

CAR investigations require a meticulous accounting of relevant factors, which often begin with Faro three-dimensional laser scanner that takes a 360-degree digital image of the crash site.

“We scan everything within a 30-foot radius of the accident in order to capture the site exactly the way it was on the day of the crash,” Masock said. “Then we gather other 2-D images, blood draws and medical records, we look at skid marks and gouges, weather conditions, light conditions, timing, and many other things.”

The information is then run through a series of mathematical models, which help investigators identify plausible scenarios for the cause of the crash.

“Once we have all this, we can see if the way drivers reacted are inside the norm or outside the norm, and that helps us resolve safety issues if there are any.”

The work requires intellect and rigorous training.

“It takes a little bit of physics, calculus, trigonometry. This isn’t an assignment where you can just put a guy out there and say, ‘get to work.’ I have above 1,000 hours of training specific to accident reconstruction.”

Collision reconstruction is increasingly data-driven. Masock relies on a massive database and software program known as Interactive Driver Response Research (IDRR), which compiles and categorizes the factors in accidents from a voluminous data trove of case studies and driver tests.

“After adjusting for baseline factors, I can use IDRR to compare an accident like [the one from Feb. 5] with a ton of other models, and that helps me we work backward toward a cause,” said Masock.

In reconstructionist speak, for example, he will establish a car’s “stiffness value” from which he can create a “crush profile” that is used to derive the quantities of force and velocity at play, and uses all of these measures to paint a picture of the accident from start to finish. “There is a ton of data that goes into this work,” he said.

The CAR unit is a multi-jurisdictional outfit that works with different agencies across the county. Masock is part of a team that includes two full-time detectives and seven other part-time specialists who participate with CAR as a secondary assignment.

The CAR unit is accessible to Holladay City through its participation in a county-based special operations cost-sharing program administered by Unified Police Department (UPD), which allows cities to pool resources to make special operations like the CAR unit more affordable. Other regional resources include SWAT, K9, violent crimes, special victims and emergency rescue services.

Councilmember Paul Fotheringham lauded the cost-sharing program at a recent public hearing. “The fact that we have this [accident reconstruction] resource is fortunate. Some of the cities that have opted out of this program can tie up their entire detective resources for weeks on an instance like this. This is one of the major reasons to stick with UPD, because economy of scale and shared resources makes so much sense,” Fotheringham said.

The cost-sharing formula is weighted heavily toward call volume, meaning cities pay mostly based on how often they solicit those services. Other fee allocation factors include a city’s population and the taxable value of the property implicated in incidents.

Masock’s Feb. 5 investigation has not yet been made public, but often the findings of his reports prompt action by state and local officials. One of the CAR unit’s primary motivations is improving road safety. Recently, Masock’s team investigated a spate of accidents on a stretch of Bangerter Highway under construction. They determined cars were crashing because a traffic light was over 250 feet away from the stop line. After Masock’s work, the Utah Department of Transportation (UDOT) adjusted the traffic light and the problem was resolved.

In the case of the Feb. 5 accident on Holladay Boulevard, the investigation has not been completed. However, partly in response to the February fatality, council members discussed lowering the Holladay Boulevard speed limit during a March 5 hearing.

“I think it makes sense to reduce the speed limit from 40 to 35 along Holladay Boulevard beginning at the end of the Village Zone,” said Councilmember Dan Gibbons, whose district includes the stretch of roadway where the accident occurred. “There are some dramatic curves in this road, and it is 100% residential all the way down. Additionally, we have [Cottonwood] Elementary School here. To me the elementary school presence is the clincher.”

The council has initiated a process to begin a speed limit change, but an official ordinance remains forthcoming. Traffic is a growing concern for Holladay residents and in a recent Mayor’s Message, Mayor Robert Dahle issued a “long dissertation on traffic congestion and speeding” to assure residents that his council “is aware there is an issue,” making the case that safety issues are exacerbated because the city is infrastructurally under par.

CAR unit’s work is not just about safety — it’s also about justice.

“Part of the reason we reconstruct collisions is that justice needs to be served. After an investigation I might testify before 12 attorneys. Then they take my report and look at the totality of the circumstance and determine what the proper legal action is in any case. Sometimes we discover that an individual’s behavior in an accident is so egregious — negligence on top of negligence on top of negligence — that our work will change a conviction from a felony two and bump it up to a felony threes charge. But conversely, our reports can mitigate the consequences for people involved; somebody may have died, but it was less an individual’s fault than it was the result of outside circumstances,” Masock said. “Our work can run the gamut.”