Technology Tools Help Drive Higher Accuracy of Crash Scene Documentation

By Bob Galvin, RS Galvin & Associates

For Truly effective documentation of crash and crime scenes, investigators in sheriff’s offices need not only solid forensic training and skills, but powerful technology, too.  At the core of investigating and processing these scenes is careful documentation since it represents a permanent written record that will show scene conditions and evidence.  Ultimately, once a scene is measured, a detailed 2D or 3D diagram is created that must withstand scrutiny in the courtroom.

As sheriff’s office still wrestle with tighter budgets, obtaining the most current technology is difficult. In many cases, the total station remains the standard measuring tool that is highly reliable and usually affordable, and which can be used with low cost data collection software and scene diagramming programs.  Other measuring methods such as laser systems, laser scanners, and photgrammetry also are solid documentation tools, yet the total station is predominantly used since it can take fast and very precise ground measurements.

Total Stations Used With Aerial Mapping

     The Nye County, Nevada, Sheriff’s Office is one of the first in the state to pursue technology for its mostly crash investigations.  Leading this effort is Sheriff Tony DeMeo, who over-sees 70 deputies covering his office’s sprawling northern and southern commands of Nevada.  He uses two Sokkia SET550RX total stations, and the Crash Zone and Crime Zone diagramming software from The CAD Zone, Inc., which enables him to produce two and three dimensional diagrams.  Sheriff DeMeo was able to purchase his two total stations, which he personally specified after learning Sokkia was frequently used brand in crash investigations, and the diagramming software with PETT funds or Payments Equal to Taxes paid to Nye County for the Yucca Mountain Nuclear Waste Repository Project.

The Sokkia SET550RX total stations were chosen for several valuable capabilities: enhanced environmental durability, including extreme heat and cold, the finest powder dust, and the hardest driving rain; measurement range of 1,310 feet; display of crash scene measurement results within 1.7 to 4.2 seconds under any circumstance; and a narrow red EDM (electronic distance meter) beam for pinpoint reflectorless measurement.

The total stations and drawing software are used mostly for serious injury and fatal accidents.  Because of the severity and scope of these scenes, Sheriff DeMeo often will overlay mapped scenes on top of aerial images of them provided by Google Earth. “We do this often because it is evidence that will be used in court,” the sheriff said.  “And people in court can see exactly where an accident occured.”  Another benefit is that layers of the scene can be created with The Crash Zone software and pulled out for observation and analysis as needed.  The layers show specific sections or details of a crash scene.

Huge Time Savings

     When Nye County Sheriff’s Office investigators map a crash scene, the total stations plot evidence points as they are captured.  “This allows investigators to see immediatley if a scene was accurately plotted,” Sheriff DeMeo said.

By using the total stations, Sheriff DeMeo estimates scenes are documented 60 to 70 percent faster compared to, say, using a steel tape measure or measuring wheel.  And, he adds, “We’re giving the judge and jury a more realistic portrait of the scene than we have in the past, and, with aerial photo overlays of a scene, exactly where an event happened.”

According to Sgt. Mark Kimsey of the Traffic Homicide Division  of Hamilton County Sheriff’s Office in Chattanooga, Tennessee, the public is demanding more intensive crash investigations to learn why the rate of crashes is rising, how they occur, and out of concern for increased road safety.  Sgt. Kimsey works with one other sergeant and two investigators investigating crashes.  They mapped 100 crashes in 2011, 18 of which involved fatalities.

Older Total Stations Still Going Strong

     In this tight-money economy, aging technology tools oftentimes must continue handling the rising number of crash scene investigations.  Which is why Sgt. Kimsey still uses two older Topcon total stations, one ten-years old and the other total station five years-old, and equipped with prism poles.  The total stations, used roughly 100 times a year and still going strong, are married with The CAD Zone, Inc.’s Pocket Zone  data collection software.  The Pocket Zone serves as both a data collector and a true CAD program.  It connects to many total stations and laser measurement systems, which allows the user to accurately record all 3D point and line data shot at the scene.  “We wanted to be able to diagram a crash right at the scene,” explains Sgt. Kimsey, “and then shoot our points from a total station right into The Pocket Zone, which will put it straight into our desktop diagramming program.”

As with Sheriff DeMeo, Sgt. Kimsey considers using a total station a highly reliable method for scene documentation.  “It’s extremely rugged,” he said.  “We’ve shot in all kinds of weather-below freezing, 100 degrees, pouring rain, snow and ice, and never had a problem collecting our data.”

Identifying Most Recent Evidence is Focus

     Determining what evidence is relevant at a crash scene is crucial to accurate documentation.  That’s the opinion of Sgt. Paul Wade, Supervisor of the Major Accident Reconstruction Team with the Orange County, California, Sheriff’s Office.  Mapping crashes at intersections can be especially tricky; due to prior accidents, there can be substantial evidence in the street that was brought there by other vehicles at other times.  “Some of the difficulty you have when you go out there is trying to identify what (evidence) exactly is involved in a crash,” Sgt. Wade said.  “We take photgraphs of the scene, and all of these other gouges and skid marks will show up.  This is when your experience kicks in, looking at the items and determining what evidence is involved in the scene and what is not.”

Preserving Scene Evidence, Moving Traffic Are Challenges

     Preserving scene evidence during a crash investigation is another challenge Sgt. Wade confronts.  For one scene he was investigating, the fire department was trying to extricate a person from a car.  Recalls Sgt. Wade: “We’re doing our work, then we hear machines and observe them (firefighters) tearing our car apart for practice.  That was our evidence?” Still another problem can be controlling moving traffic at a crash scene.  Sometimes, cars may actually enter the crash scene itself as an investigation is in progress.  “I’ve had cars coming into the scene at 50 MPH, and we’ve had tow truck drivers not paying attention and almost running over our deceased body,” Sgt. Wade reveals.

‘Reflectorless’ Mode Ideal For Short Distances

     Because crash scenes can occur during the day or night, total stations are equipped to handle both situations.  Most total stations are offered in either reflector mode, a requiring use of a prism, or reflectorless mode, which allows for measurements to objects or points without having to place a prism at those points.  Some total stations come equipped with both modes.  “The reflectorless total station is great at night,” Sgt. Wade said.  “The aiming red dot on the total station will precisely hit the target it is aimed at.”  The operator sets the total station’s target height and then aims it at the desired evidence point, which, for example, could be a tire mark.  By pressing a button on the total station’s data collector, the evidence point is captured, and the total station has measured the slope distance.  And, this has been accomplished without a prism and someone standing over it.  “The red aiming dot helps because it’s hard to see the prism looking through a total station,” Sgt. Wade explains.  Likewise, he adds, “For longer scenes, you’re going to shoot reflector mode, but, again, the red aiming dot helps because it’s hard to see the prism looking through a total station.  So, you leave the total station in the regular mode and you activate the red aiming light and you’ll see the red light refracted back to you from the prism,” Sgt. Wade said.

Since most crash scenes have relatively short distances, they can be shot with a total station in reflectorless mode.  This will speed up scene measuring dramatically compared to using manual methods.  Sgt. Wade reports that by shooting his crash scenes reflectorless, “We’re getting a scene mapped in one quarter of the time.”

Identifying Road Profiles Easier

     Brad Booth, Senior Reconstructionist with Precision Mapping and Reconstruction in Rapids City, South Dakota, would agree with Sgt. Wade that correct identification and accurate capture of scene evidence is paramount in any investigation.  Which is why the total station has become such a pivotal technology.  “With the introduction of total stations, we’re able to precisely map the evidence we identify as well as the road designs or profiles and topography of the road,” Booth, a former traffic investigator with the South Dakota Police Department, said. For Example, Booth points out that is South Dakota there is typically a three percent crown in the center of the road, and that by working with 3D crash mapping and diagramming  “we can actually see that (crown) now when we go out and map.”  This also means more scene evidence points must be captured, which a total station can easily and quickly accomplish. “Once we do that, we can accurately place vehicles over the evidence, and we can also do animatin,” Booth said.

Using current mapping technology is particulary important for Booth as he notes that crashes investigated in Rapids City overall are trending upward.  In 2011, for example, there were 2,539 reportable accidents.  Most crash scenes that Booth investigates are in rural areas, so they measure 100o feet or longer.  With such huge scenes, collecting evidence points quickly is a priorit.  “With a total station, you can shoot to a prism in about three seconds.  And I’m taking 400 to 500 measurements regularly per scene. I’ve taken as many as 1000 measurements at a crash scene,” Booth added.

Fatal Crash Underscores Total Station’s Value

     While tape measures still are used today as the only tool or in conjunction with other equipment, their accuracy cannot match that of a total station.  Booth knows because one crash scnen he handled showed how critical measurement accuracy is.  The incident involved a van with Girl Scouts whose driver was turning a corner on a road too fast.  The driver was forced to overcorrect the van, causing it to veer into the opposing lane and slam head-on into another vehicle, instantly killing two of the Girl Scouts.  Booth, a state trooper at the time. had used a tape measure to map the scene which was just over 700 feet, and so had to move the tape measure twice to complete measurements.  He then produced a hand-drawn diagram.  Meanwhile, the South Dakota Department of Transportation also mapped the scene, although using a total station, and had delivered its completed diagram to Booth by the time he got to his office the next morning,  Upon viewing the diagram, said Booth, “I was off with my measurements by over a foot.  I decided at that moment it was time we jumped onto total station technology.”

‘Seamless Integration’ of Scene Details Aided By Suite of Tools

     By now, it’s clear to see that crash scene mapping is a combination of investigative training, skills, and experience along with reliable, precision oriented equipment.  Typically, the equipment includes a total station, data collector (in many total station models a data collector is built in), data collection software, and a diagramming software program.  These tools allow aseamless integrationof evidence capture, plotting of evidence points, and creation of a final scaled diagram that may be used for courtroom presentation.  Booth uses a Leica total station, although he is tansitioning to a Sokkia 50R reflectorless total station, as well as a handheld Pocket PC, TDS Recon data collector, MapScenes Evidence Recorder software, and ARAS 360 crash diagramming software.  Contributing strongly to the seamless integration of scene documentation, Booth says, is the MapScene Evidence Recorder.  This is due to the software’s ability to allow its user to visually verify ongoing field evidence collection-on the spot-high-definition graphics, intuitive coordinates setup, and automatic saving of each measurement to ensure data security.  Data security is crucial when documenting crash scenes.  Says Booth:  “The Evidence Recorder is very intuitive and does such a good job of maintaining integrity of data we shoot.  You can change one shot and  change codes.”  However, Booth notes, “When we change codes the software flags this.”

Robotic Total Stations Boost Efficiency, Accuracy, Reduce Errors

     Dave Forystek, formerly a sergeant with The Flint, Michigan, Police Department’s Traffic Division, actually spent much of his time investigating and mapping crime scenes.  To do so, he used a Sokkia SRX5 fully robotic, single-operator total station with Archer Field PC, Mapscenes Evidence Recorder data collection software, and MapScenes Forensic CAD software.  Sokkia is one of only a handful of total station makers who offer robotic total stations.  The robotic station adds automatic tracking and radio communication to a radio and data collector at the “target” or pole.  Consequently, no person is required at the instrument-only at the target-reducing the need for a second operator.  Robotic total stations also are servo-motor-driven, which means they are paired with some typed of encoder to provide position/speed feedback.  They measure both in the X-Y (horizontal) plane and the Z (elevation) axis.  With these capabilities, robotic total stations search for, then lock onto the target and then automatically follow it as the investigator moves it around a crime scene.  While the total station tracks the target, it is constantly updating the data collector.

According to Sgt. Forystek, “It’s the combination of speed and accuracy and the amount of evidence you can gather” that makes the robotic total station so valuable.  For example, he explains, if an investigator enters a 3000-4000 square-foot nighclub to map it using a tape measure, he will need to walk around it many times, and probably need to traverse around some evidence.  “Using a robotic total station in an interior scnen like this, I can stand in one location and shoot just about everything I need,” Sgt. Forystek adds.

More Measurements in Less Time a Chief Benefit

     Although there are today many options for crash scene measuring, the total station undoubtedly will remain the most ubiquitous and often used documentation tool.  And for good reason given its many benefits:

  • The ability to take a large number of measurements in a short amount of time.
  • Reduced time spent at the scene means partially or fully closed roads can be re-opened more quickly, which raises safety for both investigators on scene and waiting motorists.
  • By combining the total station with software needed to process collected data points, a simple diagram can be created at the scene within minutes and checked for any missed points before leaving.

A scaled diagram created with data first accurately shot with a total station and that has been secured via collection software allows for careful analysis of scene events and details.