“We wanted something that could be more efficient and get the supervisor out more quickly by starting to map the road himself, and by the time he was done the secondary detective had the evidenced mapped,” Det. Refairn explained.
Initially, the LVMPD acquired Sokkia SRX series robotic total stations. Robotic total stations allow the operator to control the instrument from a distance via remote control. This removes the need for an assistant staff member as the operator holds the reflector and controls the total station from the observed point.
The Sokkia SRX series are fully tracking and auto-pointing robotic total stations, with on-demand target reacquisition and reflectorless EDM (electronic distance meter).
When total stations are referred to as being “reflectorless,” this means the device can measure objects or points without the need of placing a prism a those points. This advancement saves tremendous time for the total station’s operator, and it improves safety while mapping a crash scene.
GPS helps map longer scenes
The LVMPD’s Fatal Crash Investigation Detail prides itself on being techno-savvy, which is why in 2010 it added three new Sokkia GRX1 GNSS systems--GPS total stations-- to its total station arsenal. The GPS total station is becoming very popular among total station users since it can give position of a point accurately anywhere on the globe. The GPS can measure base lines with high accuracy, and controls points with no need for line sight. The GPS total station also can map far greater scenes and distances than more conventional total stations.
Traditionally, total stations have worked on the principle of signal reflection off a line of sight between the total station and a prism reflector. The GPS total station is effective for establishing control points because its antenna automatically finds these via satellite signals, thus giving a fixed position at a crash scene.
The GPS receiver provides high speed of supervision, higher accuracy (even in harsh conditions) and low power consumption. These total stations also are lightweight, and can be used on a tripod, in a backpack, or on a car or other mobile objects.
Units Complement Each Other
What Det. Redfairn values about his department’s total stations is that they can all be used together, and complement each other. For example, he said, “Neither one of the robotic or GPS total stations is the perfect machine, but when you have the two of them together you’ve almost got the perfect system. Where the GPS can’t go because of limitations (GPS units require open sky since they are satellite-based), the robotic total stations can,” Det. Redfairn said.
The detective notes that combining robotic and GPS total stations allows mapping of very large crash scenes. “You can have two or three people measuring the scene, then you can marry the data collected from these total stations to create a diagram,” Det. Redfairn said.
With these significant strides in total station technology, are traffic investigators safer as they measure the still hectic, distracting and perilous crash scenes present today? Det. Redfairn believes so.
“It’s not so much the safety of the operator at the scene, because he’s not going to be shooting from real far away, hence, being out of the way of bypassing traffic,” Det. Redfairn said. “But it allows the scene to be cleared more quickly.” And this, argues Det. Redfairn, is where safety levels are heightened.
Safety a Factor in Total Stations’ Purchase
Sgt. Sarah Crane of the Utah Highway Patrol would agree with Det. Redfairn’s assessment of total stations and their contribution to increased safety for crash scene investigators. A nine-year highway patrol veteran and a trained reconstructionist, Sgt. Crane uses a Topcon 3100 series reflectorless total station.
Utah Highway Patrol racks up 250 fatal crashes per year. Because the state is so spread out, the highway patrol uses 17 of the Topcon total stations, which are distributed among several regional sections throughout the state for use by the patrol’s crash investigators.