Tractor Trailer Underride Accidents
Not Your Average Everyday Occurrence

By Jack Murray, CLI, CFE


Arlington, TX Police Dept. Form ST-3


It was approximately 5:30 PM on a bright clear afternoon, on a relatively busy six lane highway in suburban Arlington, Texas. A tractor trailer driver, on his way to make a delivery suddenly realized he had overshot his turnoff and decided to turn around and go back into the opposite lane of traffic. This required making a u-turn at a break in the concrete and grass median that divided the three lanes of east bound and three lanes of west bound traffic.

About this same time an ambulance with two crew members was returning from a call. The ambulance rounded the large sweeping curve to find the rig blocking all three lanes of traffic. There was no time for the ambulance driver to stop, or to swerve off the road. The ambulance went under the side of the tractor trailer, causing severe injuries to the driver and his EMT passenger.

In this case' causation was relatively easy to ascertain, but in most cases one has to ask, "How could anyone not see a 48 foot long, 13 foot high semi trailer?"

According to the National Highway Traffic Safety Administration (NHTSA),1 in a very large percentage of these cases, driver expectation is the major factor. The exact percentages are not available due to the uneven reporting practices of various law enforcement agencies throughout the country.

One does not expect to find a tractor trailer rig, as big as a small house, across the road in front of you. This factor is equally true in daytime or at night.

At night, the problem of crosswise trailers is compounded, because the lights on the tractor appear to be in the oncoming traffic lane. As a driver approaches the tractor, the tractor's lights seem even brighter, and the driver's attention is diverted even more. This "light wall" makes it more difficult to see the tractor portion of the rig. By the time the driver realizes the situation, there is no time to brake, or to swerve, and the car goes right under the trailer.

Perception reaction time (PRT),2 becomes greater than 1.5-2.0 seconds, currently accepted as a norm in the industry, and established by case law in Texas.(3)

If the oncoming vehicle is traveling at 50 miles per hour, (75 feet per second) and the PRT is two seconds, the vehicle would travel 150 feet before its driver would do anything, (brake, change lanes, etc) to avert the crash. The longer the PRT, the more distance would have been traveled before any action was taken.

In 1997, we had two cases in which a car drove under the back of a stopped tractor trailer rig. Again, one has to wonder how the driver could not have realized the truck was parked. Same problems: driver perception and visibility.

On toll roads with adequate lighting, this is not as common as on busy interstates, with prolonged areas of relative darkness. The lack of back lighting eliminates the trailer being silhouetted, making it much more difficult to identify.

At night, even if there is back lighting and the truck is silhouetted, it's a dark outline against a dark background, and it still cannot be easily seen.

Depending on weather conditions at the time, and the color of the tractor, there are situations where you may not be able to see the whole rig, possibly just the tail lights. White and silver are favorite tractor colors and very dangerous in foggy weather. Black and other dark colors are equally difficult to see, even in clear weather.

On today's super highways, there is a proliferation of ambient lighting from businesses along the highway--neon lights, yellowish sodium vapor lights, red lights, green lights. This makes amber or red marker lights on the side or the back of a trailer even more difficult to distinguish.

Most trailer beds are approximately four feet from the ground. The average height of the lights on a passenger vehicle are 24-27 inches, on a pickup truck or a sport utility vehicle approximately 33 inches. With properly adjusted headlights, the brightest spot of the low beam is directed about a degree and a half down from the horizon and about two degrees right of the vertical. Thus, the major part of the beam of most passenger vehicles is below the bed of most semi trailers.

Side marker lights, positioned at an angle across a highway, severely limit the amount of reflected or direct light that reaches oncoming drivers. A Society of Automotive Engineers (SAE) paper4, by Messrs. Brown, Bookwalter, and Guenther, "Underride Accidents: Headlights, Glare, and Nighttime Visibility," concludes that, "glare increasesperception time" and "side marker lights are not adequate warning devices because they are not associated with a trailer, not because they cannot be seen at a distance."

Dr. Merrill J. Allen, O.D. PhD.5 in his book, "Forensic Aspects of Vision and Highway Safety, makes the point that, "A modern windshield, set at an angle of 60 degrees from the vertical reflects about 20 per cent of the visible light and provides a location for dust, water droplets, and bugs to collect. (2)

What then, other than education and extreme caution, can be done to alleviate this problem?

    Among other things, Dr Merrill suggests:
        Ban black on all motor vehicles.
        Make white mud guards standard and ban tinted glass in windshields.
        Ban all add-on tint to windows and lights.

Another thing, that helps a great deal, is keeping the trailers clean. Even the most elaborate lighting and reflector system can be negated if it is coated with road grime and dirt. Lights or reflectors, on the top of the rigs, seldom get cleaned. Realistically, how does one wipe off a unit that's thirteen feet from the ground? This means driving the rigs through trailer washes at truck stops. Most companies do not have provisions for their drivers to do this.

Another answer is reflective tape, such as 3M's Scotchlite Diamond Grade Conspicuity Sheeting. This is a reflective tape that comes in 2", 3" and 4" widths. It is designed so that when it is placed around the bed of a trailer holes can be cut in it to allow lights and standard reflectors to poke through it.

In December 1993, the Federal Motor Vehicle Safety Standards (FMVSS)6 regulation requiring the use of retroflective sheeting or tape went into effect. (3 )  
This regulation requires, " horizontal strips of alter nating red and white pieces beginning and ending as close as practical to the front and rear of the trailer at about four feet from the ground. Rear markings must include (a) alternating colors across the width of the trailer, from side to side, approximately four feet from the ground, (b) pairs of white reflective material applied horizontally and vertically to the right and left upper contours of the trailer as close to the top and as far apart as possible and (c) a sheeting strip of alternating colors across the full width of the rear underride protection bumpers."

In those cases where sheeting is impractical, patterns consisting of two or three red reflectors, alternating with two or three white ones must be affixed.

NHTSA regulations, for reflective sheeting or reflective tape, require that such material be alternating red and white with each color at a minimum 2" high and 6" to 18" long. One color cannot exceed two thirds of the total segment. The segments may be broken, but should be evenly distributed to cover at least 50 percent of the length of the trailer.

The big problem is that these regulations apply only to vehicles manufactured after December 1, 1993. The explanation we have received, in deposition, from defendant trucking companies, for not retrofitting their older rigs is cost. However, the manufacturers we contacted, 3M, Avery, and Reflexite, estimated they can provide the necessary materials to retrofit a 53 foot trailer for about $75.00 and it takes less than one hour to apply them. The National Highway Traffic Safety Administration estimates that the average cost would be about $102.00 per trailer.

Where does the legal investigator fit into these cases? The primary role of the investigator, is to gather intelligence. Under the Federal Rules of Evidence (Rule 703), only an expert, so designated by the court on the basis of their "education, experience and training," can give an opinion as to causation, or degree of negligence.

Investigators should:

    First, and foremost, obtain any photos taken at the scene of the accident. Examine them as carefully as possible. Look for the reflective devices and markings. Are they obviously dirty? Do they show reflected light from the headlights of other vehicles at the scene? Do they meet federal requirements?

Go to the scene of the accident at approximately the same time as the accident occurred and document the problems of visibility and/or ambient lighting. A videotape, of what your driver could see is most helpful in making this point to a jury.

If sunshine in a drivers eyes is alleged to have been a part of the problem, get an expert in showing the position of the sun at the time of the accident to verify the problem. One such company is Macinnis Engineering Associates Ltd. in Richmond, British Columbia, Canada. They can provide graphs and charts that show the position of the sun, in relation to the location of the accident, at any given time, on any given date. More information on this phenomenon can be gleaned from A Society of Automotive Engineers paper (SAE 950359), by Messrs. Macinnis, Williamson and Nielsen, entitled, "Sun Position and Twilight Times for Driver Assessment.* Consider an expert in night vision and the problems of target fixation. Your local military air base can put you in touch with someone who is familiar with this phenomenon. If there is not a military installation nearby, find out where commercial pilots in your area take their annual eye exams. Flight surgeons can usually put you in touch with an appropriate expert.

If weather is a factor in visibility, get a certified meteorologist for a break down on weather conditions at the time and place the accident occurred and document that with certified copies of the weather reports from The National Climatic Data Center, 151 Patton Avenue, Asheville, North Carolina 288801-5001.

Know the regulations better than the trucking company does. Obtain your own copy of the Federal Motor Carrier Safety Standards, (FMCSS), regulations, Department of Transportation's publication 49 CFR part Docket No.80-9; Notice 4; RIN 2127-AA1 subtitled "Lamps, Reflective Devices, and Associated Equipment ." (4)

3M has a very fine booklet entitled, "Conspicuous Problems......Conspicuous Solutions." Also, get a copy of their Product Bulletin 980, which describes their Scotchlite TM Diamond Grade Conspicuity Sheeting technical data as to reflective quality and other specifications. (7)

Inspect the vehicle itself. Obviously, the defendant is going to have it all cleaned up and shiny for you, but you can still locate all of the reflective devices, and document in your photographs the difficulty in reaching and/or cleaning them.

Make sure that you get all of the defendant company's training manuals. Do they train their drivers to handle situations where they may be turning, or pulling off the road, in darkened areas? Usually their answer is, "We hire professional, experienced drivers. They are expected to know these things." You can usually show the drivers have had little, or no, training, for these situations. Does the defendant company have written regulations concerning the cleaning and inspection of their vehicles when they are on the road?

Ascertain whether other trucks, within the company fleet, are outfitted with reflective surfaces that meet the 1993 regulations. This can prove to be very damaging testimony later on as the company attempts to explain why some trucks are outfitted that way and others aren't.

Most importantly, get an experienced, competent, accident reconstructionist, with truck underride experience, to consult on the case. Without that expertise, that ability to express opinions and conclusions in the courtroom, your work will not be admissible.

1.) National Highway Traffic Safety Administration, Docket Section, Room 5109, NASSIF Building, 400 7th Street S.W., Washington, D.C. 20590

2.) Traffic Accident Investigation Manual, Volume 2, 1994, J. Stannard Baker, Lynn Friecke, Traffic Institute, Northwestern University, Evanston, Illinois.

3.) Samford vs Duff 483 S. W. 2nd 517 (Tex Civil Appeals Corpus Christi 1972)

4.) Society of Automotive Engineers, 400 Commonwealth Drive, Warrendale, Pennsylvania 15096-0001; Ph: 412-776-4841

5.) Forensic Aspects of Vision and Highway Safety, Merrill J. Allen, O.D., PhD, Bernard S. Abrams, O.D., Arthur P. Ginsberg, PhD., Leslie Weintraub, O.D., Lawyers & Judges Publishing, 1996, Tucson, Arizona

6/) Federal Motor Vehicle Safety Standards- Federal Register; December 10, 1992, pp 58406-58416

7.) Minnesota Mining Company, Commercial Graphics Division, Building 220-6W-06, St Paul, Minnesota 55144; Ph: 612-737-3136

J. W. Jack Murray, CLI, has been a NALI member since 1984. He specializes in motor vehicle accidents and vehicular crime. As a member of the Society of Automotive Engineers, he has testified as an expert in underride cases in Federal and state courts. He may be contacted at (214) 902-9156. You can email him at

Copyright 1998 by Jack Murray. All rights reserved.
No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, to include photocopying and recording, or by any information storage and retrieval system, without prior permission in writing from the author.

Originally published in the February 1998 issue of "The Legal Investigator, The Official Journal of the National Association of Legal Investigators, Inc." (NALI.) .

Contact NALI at for information on obtaining copies of past articles.By: Jack Murray, CLI, CFE