How do truckers measure the height of their truck and load?

Triplesix, rcelmo -

Thank you for the additional comments. The Texas Legislature has passed a number of exemptions for certain types of loads or truck operations. Hay can be hauled wider than legal width without a permit - didn't think about the fact that hay would pick up moisture as well during a rain storm.....good point. Most agricultural loads can operate above legal load limits during harvest and other types of loads can be over length or over width without a permit (electric transmission poles, pipe, water drilling rigs, etc.)

The measuring stick seems straight forward, but I still can't understand how you can judge the load height while standing on the ground and looking up 14 or more feet in the air at the relative height of the load and the measuring stick. Is there some type of gage or meter at your eye height that shows the height of the pole when you judge it to be even with the top of the load?

I've read reports about the Skagit River IH -5 bridge collapse - National Transportation Safety Board (NTSB) conducted an investigation which took months to complete ...... of a crash that was all over in a few seconds. The trucker was hauling a piece of OS/OW oil field equipment - essentially a large steel box, and was over height by 2 inches. The trucker felt squeezed in by another truck and hugged the outside lane edge - the corner of the box he was hauling started clipping girder supports (it was a steel truss bridge) and as he looked in his rear view mirror the span collapsed into the river. No one was killed - a blessing from God. However, he is now facing a $17 million lawsuit from Washington State. He had a pilot car running ahead of him, the truck driver said he didn't see the height pole hit any of the bridge girders....however, a car driver directly next to the pilot car said he saw the pole hit 3 or 4 girders.......not sure how far away you can be from the pilot car and tell if the height pole hits or not. I've not seen this type of operation in Texas - only operations in which the pilot vehicles travel ahead of the OS/OW load and raise wires or check heights or widths or under clearances (rail road crossings for example). The measurements are made from the ground, not a moving vehicle.

I've been involved in collecting pavement condition data during an NTSB investigation of a multi-fatality bus crash on IH 35. We measured pavement skid resistance, rut depth, pavement cross slope and other factors over a 2 day period. I watched as NTSB and TxDPS had the pavement sprayed with water (it was raining at the time of the crash) and then ran their cars at different speeds slamming on the brakes to determine braking distance.....maybe a general indicator for the SUV, certainly not for the bus. In any case the bus had an anti-lock brake system which was disengaged (legal) and very worn tires (also within legal tread depths, though no way I could pass inspection with tires like that on my Corolla).

Based on further details collected from the bus and the SUV it hit-head on in the opposite direction; using data from the engine control module, speed and acceleration / deceleration information...from the time the SUV driver was traveling at 55 mph (no problems) to the time the SUV came to a dead stop (greater than 40 g deceleration) took just 4 seconds. Crashes happen very fast and then weeks or months are spent trying to understand how they happened and what could have been done to prevent them.

By the way, most folks don't pay attention to all of the safety devices installed along the roadway to help vehicles decelerate slowly in order to save lives. Guard rail with Safety End Treatments of different designs, some thread the rail through a guide that flattens the rail into a ribbon thus absorbing energy and slowing the vehicle down; Vehicle Impact Attenuators, Crash Cushions and other devices .... all designed based on the approach speed to decelerate a vehicle with the goal of 6 g's or less (greater than 6 g's and most people will pass out and not be able to maintain control of their vehicle or escape if necessary) > 10 gs likely cause serious injury, the highest g force that a professional fighter pilot can withstand is 15 gs. Princess Diana experienced over 40 g's so did the folks in the SUV mentioned above as did several passengers on the bus.

Many folks don't realize the amount of engineering design and care that goes into designing every aspect of the roadway and each of the features such as safety devices, striping reflectorized pavement markers, rumble strips, rumble stripes, bridge clearance (height) (width), culvert safety end treatments, culvert length extensions, signing, break away sign posts, break away lighting, cable median barriers, concrete traffic barriers, median widths, clear zone widths etc. However, it is very, very difficult to design these devices so that they can work well for either a car, light pickup or a heavy truck. What works well in decelerating a heavy truck will be far too stiff for a small car. This is why sand barrel attenuators are designed with about 400 lbs of sand in the lead barrel, then the next two with 700 lbs, then 900lbs and so on until the last barrels just before the obstacle are around 1,400 lbs. Soft enough to slow down a car at the beginning of the barrier but stiff enough to 'help' slow down a truck as it moves further into the barrier. Same idea with the Texas Crash cushion design which uses empty drum barrels with different diameter holes in the top....larger holes in the lead barrel make them easier to crush, small diameter holes further into the barrel assembly.

Energy Absorption (a company) REACT 350 crash cushions are designed for high crash rate areas since they can take multiple hits and remain serviceable until the damaged portions can be replaced. There are many different designs depending on the specific application. Some VIAs are one hit only but if a life is saved, they have more than paid for themselves........

The same is true regarding pavement or bridge design - every element is designed based on a knowledge of materials, physics and structural design standards. Regarding how TxDOT can know the height of bridges? LIDAR surveys are one way - land surveying methods are another.....the bridge grades and beam designs are developed to close tolerances to meet engineering standards; but as was pointed out, if the pavement is overlaid, or milled the clearance can change. TxDOT advised Texas Department of Motor Vehicles of each construction zone in place (a 1,000 can be in operation on any given day (or night) in Texas). Changes in pavement grade can change during the course of roadway construction as layers are milled off and replaced with new materials; one lane at a time is rebuilt or an overlay is placed in one lane this week and the next lane next week. Every thing is changing in time all under traffic and every one trying their best to keep things safe ....this includes the thousands of trucking that operate Intrastate only and the thousands more that operate from Canada to Mexico and New York to California through Texas or from Texas.

Texas has 53,000 bridges both on- and off-state system though TxDOT (and every DOT in the US, is responsible for inspecting and load rating every bridge in their state by Federal law). Texas also has 195,000 lane miles of pavement or about 85,000 center line miles. A huge system to manage and maintain which is much different in east Texas than west Texas ----- Dallas or Houston, Austin, Amarillo or El Paso.

Understanding the drivers and vehicles operating on the system is just as much a part of providing a safe and economical and efficient transportation system as are the pavement, bridge and traffic control devices. The big area of study right now is autonomous vehicles and V2V, V2I future demands... we are approaching an age when vehicles will talk to infrastructure and vice versa, cars will talk to trucks and vice versa. The question will be how human drivers will relate to decision making by their vehicle.......the military has demonstrated unmanned vehicle convoys in Texas; there have also been demonstrations of autonomous vehicles operating in Dallas traffic......I am a baby boomer, and I still think that you could not program a computer to make the kinds of decisions that pilot that landed the 737 in Hudson bay made in a split second which saved everyone on board. Just too many scenarios to program and develop solutions for .....at least for now.

I do agree with the point made about the variation in truck size and weight laws from state to state....this does make the trucker's job much harder and also causes the US to be less competitive with the European Union and other countries which have unified systems. Dr. Mike Walton, a senior professor at UT has been a national and international leader working to help unify US truck size and weight laws. It is very very difficult to do though due to internal competing interests within the US....rail, oil & gas, foreign competition etc. etc.

I once attended a conference in D.C. in which the Dutch Transport Minister was asked how European Countries were able to unify and create comprehensive truck size and weight laws that were relatively consistent and accepted among 13 countries that were at war with each other only decades ago. The Dutch Minister said '.....it's because we realized we have a new enemy, it is you. (the U.S).' He meant, an economic enemy or rival that they want very much to surpass.

I've tracked off a bit from the original points....but wanted you to at least know that the vast majority of transportation professionals want nothing more than for you to arrive safely and make a profit as well.

Mike