Using Laser Rangefinders In Accident Reconstruction

I was out on the golf course this summer with my father-in-law, who is a single digit handicap golfer, and he pulled out his laser rangefinder to give me the distance I was to the pin – 106 yards. Now, I’m not as good of a golfer as he is and am most times just happy to make decent contact with the ball, so a rough distance is usually good enough for me. Before he gave me the yardage, I drew upon my former experiences as a caddie and estimated that I was about a football field away, or 100 yards. If I hadn’t gotten the true yardage from my father-in-law and went with my original estimation (and actually hit the ball straight 100 yards), I would have been close enough for my golfing purposes. Nevertheless, I flubbed my shot into a bunker and my hopes of winning the hole faded quicker than Shoeless Joe Jackson into an Iowa cornfield.

My experience that day got me thinking about how I typically measure distances during site inspections while doing accident reconstructions. My tool of choice for the last few years has always been the measuring wheel. I use it to document lane widths, line-of-sight distances, and other roadway measurements. I have also used the measuring wheel to record distances to the nearest intersecting streets, which sometimes were over a quarter mile away. For those of you who are not familiar with the measuring wheel, it requires the operator to walk out the entire distance while the wheel stays in contact with the road surface. So, in order to get the measurement, I would have to walk the entire distance and then back, which could take 15 minutes or more for just a single measurement. This process always seemed a bit tedious and time consuming — there had to be a better way. So I thought, what if instead of having to walk long distances with a measuring wheel to obtain measurements, I could acquire them in seconds with a laser rangefinder, similar to obtaining distances on a golf course? I could simply stand at one location and shoot the rangefinder towards a street sign, tree or light pole at the nearest intersecting street to get the approximate distance I needed, saving considerable time and effort.

A typical laser rangefinder used for golf or hunting will display distances to the nearest yard at an accuracy of +/- 1 yard and is capable of ranging distances over 500 yards, which is greater than a quarter mile and sufficient for most long-distance measurements needed for my site inspections. Accuracy to within 3 feet over these long distances is acceptable for the majority of accident reconstruction analyses. I started using a laser rangefinder for my site inspections and found that the time needed to acquire long-range measurements was greatly reduced and the findings were just as accurate (and in some instances, more accurate) with the laser rangefinder. The time I saved could then be used to focus on other, more important issues, such as sight-line obstructions and stopping distance calculations. Not having to roll the measuring wheel along an active roadway also helped to secure my own safety. While the laser rangefinder cannot replace the measuring wheel for short-distance measurements such as lane widths, it has become a welcomed tool in my inspection kit for those long-distance measurements and one I plan to utilize whenever I can.