Office of Planning, Environment, & Realty (HEP)
Good afternoon or good morning to those of you in the West. Welcome to the Talking Freight Seminar Series. My name is Laura Feast and I will moderate today's seminar. Today's topic is Higher Productivity Trucks. Please be advised that today's seminar is being recorded.
Today we'll have three presentations, the first given by John Woodrooffe, of the University of Michigan Transportation Institute. The second presentation will be given by Tim Lynch, of the American Trucking Association. The final presentation will be given by Mark Swanlund, of the Federal Highway Administration Office of Pavement Technology.
Mr. Woodrooffe is a Research Scientist and Director of the Transportation Safety Analysis Division at the University of Michigan Transportation Research Institute. He has 30 years experience in vehicle related research and is an international expert in large vehicle transport safety, efficiency, risk analysis, vehicle productivity, and progressive regulatory issues. Mr. Woodrooffe is a member and Working Group Leader of the National Academy of Sciences Committee on Fuel Economy of Medium- and Heavy Duty Trucks. Mr. Woodrooffe founded the Road Vehicle Research Program at the National Research Council of Canada in 1984 and developed it into a successful, internationally active Heavy Truck Research Laboratory. He was awarded the Commemorative Medal for the 125th anniversary of Canadian Confederation, on behalf of the Governor General of Canada for his contributions to the National Research Council of Canada.
Tim holds the position of Senior Vice President of the American Trucking Associations (ATA). Mr. Lynch is charged with developing and executing strategic plans to assure that ATA and its member motor carriers achieve the necessary public policy goals to keep the U.S. trucking industry safe, efficient, and profitable. Tim rejoined ATA in October of 2005, after eight years as President of the Motor Freight Carriers Association. Prior to joining MFCA, Mr. Lynch was Vice President, Legislative Affairs for the ATA. From February 1982 until December 1992, Mr. Lynch was Vice President, Government Affairs at Roadway Services, Inc., of Akron, Ohio. Mr. Lynch spent five years working as a professional staff member for the United States Senate working for the U.S. Senate Committee on Commerce, Science and Transportation. His legislative responsibilities included the motor carrier, railroad and barge industries, Amtrak and amateur sports.
Mr. Swanlund is the Senior Pavement Design Engineer for the Federal Highway Administration. His responsibilities include pavement evaluation, pavement design, and pavement surface characteristics. Mr. Swanlund has worked for the Federal Highway Administration for 22 years and is a registered Professional Engineer in the State of Colorado.
I'd now like to go over a few logistical details prior to starting the seminar. Today's seminar will last 90 minutes, with 60 minutes allocated for the speakers, and the final 30 minutes for audience Question and Answer. If during the presentations you think of a question, you can type it into the smaller text box underneath the chat area on the lower right side of your screen. Please make sure you are typing in the thin text box and not the large white area. Please also make sure you send your question to "Everyone" and indicate which presenter your question is for. Presenters will be unable to answer your questions during their presentations, but I will start off the question and answer session with the questions typed into the chat box. Once we get through all of the questions that have been typed in, the Operator will give you instructions on how to ask a question over the phone. If you think of a question after the seminar, you can send it to the presenters directly, or I encourage you to use the Freight Planning LISTSERV. The LISTSERV is an email list and is a great forum for the distribution of information and a place where you can post questions to find out what other subscribers have learned in the area of Freight Planning. If you have not already joined the LISTSERV, the web address at which you can register is provided on the slide on your screen.
Finally, I would like to remind you that this session is being recorded. A file containing the audio and the visual portion of this seminar will be posted to the Talking Freight Web site within the next week. We encourage you to direct others in your office that may have not been able to attend this seminar to access the recorded seminar.
The PowerPoint presentations used during the seminar are available for download from the file download box in the lower right corner of your screen. The presentations will also be available online within the next week. I will notify all attendees of the availability of the PowerPoints, the recording, and a transcript of this seminar.
We're now going to go ahead and get started. Today's topic, for those of you who just joined us, is Higher Productivity Trucks. Our first presentation will be given by John Woodrooffe, of the University of Michigan Transportation Institute. The second presentation will be given by Tim Lynch, of the American Trucking Association. The final presentation will be given by Mark Swanlund, of the Federal Highway Administration Office of Pavement Technology.
As a reminder, if you have questions during the presentation please type them into the chat box and they will be answered in the last 30 minutes of the seminar.
First off, thank you very much for the introductions and organizing this webinar. Also depending on the time zone you are in, good morning and good afternoon to the people out there. I'm going to be talking about the essentials of long combination vehicles. This is experience that has been gained over the years and in other countries with respect to this kind of activity. I think a major concern has to do with safety. When we look at the task of improving safety, we have a model here that shows the three axes. One of the axes is the probability of a crash which is exposure related. We have exposure on the horizontal axis. From a safety perspective, anything we can do to shrink any of the axes will result in improvement in safety.
We have a different way to look at the problem and to improve the safety outcome. I think of general modal transport as having three major components. One component is technology, which we recognize readily as things like ABS brakes, electronic control systems and so on. Another component is the human, which we all know very well so I do not believe I will have to discuss that. Finally, we have policy. I think the influence policy can have on safety is highly under appreciated. If we try to represent this on an imaginary timeline, we look at the human as the human was really responsible for most of the safety benefits. When I say human, I say the direct human that is operating the vehicle, understanding, lessons learned, education and so forth. The capability of the human with respect to safety rose over time, but I believe that in the conceptual framework, it's essentially plateaued. We have a natural plateauing of our expectations for human intervention from within the safety regime. This had to be the operator of the vehicle versus other solutions.
Technology can be everything from road quality right through electronic systems and safety systems. I don't think there's anything in front of us that's going to plateau. There's future in the technology area that's going to be bright. Policy is something where there's a massive amount of potential for growth on the influence of safety. As we developed better systems of managing and controlling risk, true policy, I think we can see a great benefit. If you combine the policy with the technological element, then I think the gains can be quite significant. From a research perspective; I believe that the future contribution to safety from improvement will largely lie within the technology and the policy frameworks. I'm optimistic about the outcome.
So let's talk about the long combination vehicle. I think that's one topic that offers for our transport network a very promising potential. We have to differentiate between low density cube limited freight and high density mass limited freight. These two are quite separate, and the way they're analyzed needs to be quite separate. The vehicles that are involved to meet those challenges are again, very different. The efficiencies and benefits are also very different. So we're going to focus this discussion largely on the cube limited freight tasks - LCVs. We like to call the methods by which they are evaluated by performance measures, and they have with them criteria that if the vehicles configured appropriately, the vehicle will be such that it fits within a special category. This category is a vehicle that's predictably managed by a driver and has no surprises.
One of the things with respect to vehicle design is the cupping methods that we might employ. I'll talk about that later. In some cases, they can profoundly affect vehicle stability performance. Longer trailers tend to be less dynamically sensitive. Long wheel based vehicles generally have a better ride. There was two points of articulation for the A train coupling element. The two points add to the dynamic aggressiveness of the vehicle. Also, it's not roll coupled so the two trailers are completely independent and roll. The B train removes those points of articulation and couple the two trailers in roll. Removing the points of articulation is very important when you consider the roll phasing that takes place during an evasive maneuver. That is a terrific benefit to vehicle stability. That is the coupling. The C train is really a representation of the B train where instead of having an extended frame as you have in the B train, you have a couple draw bar system that hook into the back of the trailer. Here we have a self-steering axle on the dolly. That mimics the dynamic characteristics resulting from the B train and speaks to how stable a vehicle will be in a turn.
Rearward amplification is when the load of a vehicle is moving from one side to another while the vehicle is going through a maneuver. It is a very instructive performance measure. Where does the last trailer go during an evasive maneuver at high speed? How faithful is to it the track of the original vehicle? High speed friction utilization speaks to the road interface and how much is available for control, as is low speed friction utilization. Low speed offtracking is a situation where the last axle of the complex vehicle during a tight turn, say in the urban area, would encroach into something like a sidewalk area
So how do these measures roll out and what is the implication? I think it's quite instructive because I'm using load transfer ratio. If you had one measure to rely on, load transfer ratio would be the one. If you look at here, we have an A train triple at 118,500 pounds. It has a load transfer ratio of one, which the vehicle would have rolled over in this maneuver. Putting a C train coupling on it, we bring it back here to this level of 0.298 which is extremely well behaved and it is in fact, better than 80,000 pound tractor semi-trailer under those conditions that you see down here. You can see how these different vehicle options perform with respect to this. This slide was taken from the western scenarios size and weight analysis done a few years back.
That study also looks at the influence of this load transfer ratio measure with the total payload length. As the vehicle length is out, again the load transfer ratio diminishes which is a variable attribute. There seems to be some point at which it may be starting to rebound and of course, the reason this is really happening is that as the weight goes up, the vehicle has to lengthen in order to meet the bridge formula. You have the effect of increased GVW changing the characteristics and making them more stable. Surplus break to capacity, this works on the notion that as we increase the gross vehicle weight, then the number of axles on the vehicle increases and the number of axles increase at the rate such that the break capacity is increasing faster than the extra axles provide. Therefore we have more brake capacity on these larger vehicles.
Now with respect to the safety performance, there was an interesting study done in Alberta where they run LCVs on the Canadian network within that province. They run the LCVs on different classes of roads. This study looked at the road sections themselves and the frequency of LCV crashes and semi-trailer crashes in the same highway sections. They had good exposure data. The results were fairly compelling showing that the LCVs were significantly safer than the conventional semi-tractor trailer. The big thing to recognize here is the safety benefit is really driven by policy that governs the operation of those vehicles, and not necessary vehicle characteristic itself. That's a very important point to take home.
Now the Alberta study concluded that LCV fleet crash rate was about five times better than the tractor semi-trailers. The LCV safety improvement is attributed to special permit road transport policy that is minimal risk based. The other interesting thing, 42% of all the collisions involving LCVs under the restrictive regimes were under adverse weather conditions. Further improvements in safety performance of this particular LCV fleet nonetheless compared to the other fleet, the control fleet which was the tractor semi-trailer, the safety outcome was very impressive.
Now the way the program is managed is a key to the success, and I don't know that one would have to adopt all of these measures, but finding the few that make the most difference is important. A required minimum performance threshold from the company might be one of these measures. So the company that was involved in this program was known and their record was of a certain standard. There were some requirements for safety on the vehicle. Regular reporting by carriers was linked back to some central database. Highway safety and weight violations were linked to the performance evaluation. Of course in this mix, meaningful enforcement is absolutely essential. So you just can't have these rules and not be enforcing them. The last thing was that the system fostered pride, that this was a privilege and not a right. The companies really appreciated the opportunity to play in this particular 'game'; I guess you'd call it. That set it in place, a certain set of pride that seemed to ramp up the safety culture in the organization.
This slide summarizes the general benefits of LCVs. This shouldn't be a surprise to anybody. The reduction was about 44%. This is for the freight task we have in front of us. The cost savings to the shipper were about 29%. The fuel and CO2 and NOx emissions were about 32%. Road ware was reduced by 40% and that has to do with the way the vehicles are configured, the extra axles and the per axle weight is lower and you only have one steer axle in the vehicle as opposed to having to carry the same freight on the vehicles - steer axles are the most damaging axles on the vehicle. The exposure crash reduction was found to be about 44%. The policy affected crash rate reduction about five times over. That's the general picture from that particular program.
The other thing that we understand is that some jurisdictions are seeing five to seven times better safety than normal trucks. They report these internally. They have a way of reporting their crashes and so forth. So you can see that the societal value of the LCVs is fairly significant.
With respect to the technologies we might anticipate, we have lane warning departure systems. Roll stability systems and electronic stability systems, which I think are really important because they do deal with some of the more vulnerable aspects of having a vehicle and that is roll over. Another technology is forward collision systems with adaptive cruise control. Active braking systems are something that I think for the trucking industry is a very good technology. Then we have vehicle diagnostic and location system.
The argument that I think would be worth making is that we should try to have a cost benefit methodology. This methodology defines the societal value of the trucks. This particular graph would be helpful at trying to rationalize some of the value so that we can look at what the true benefits are to these vehicles. The true benefits extend not just from the shipper, transporter relationship, but they extend right to society at large.
Conclusions are that we should be thinking about creating a friendly truck category where the truck is efficient, proven to be safe, environmentally friendly, and it has some favorable impact on fuel. Performance metrics cannot only include safety; they can include other things as well. They should be fitted with advanced technologies. We need a way of tracking the performance of the vehicles because it is very important to keep on top of this. This has to do with the management of the transport system over time. We want to see a success in the safety side. We want to see a success in the productivity side. We can tweak and fine tune the transportation tasks to make the benefits and potential. We could have a very aggressive expectation of ten times the crash rates for this vehicle class compared to semitrailers. That would be obviously very aggressive, but something, some expected reduction in crash rates associated with these vehicles greater than this current happening today would be important. So more information can be found on this whole subject of vehicles that are integrated more closely with the overall aspect of transportation and transportation economics, there's been a study that is currently being wrapped up by the OECD in Paris.
OECD is a well known international body that looks at all aspects of the state of the economy and mostly in developed nations. They have a transportation arm that has been looking at heavy vehicles and the operational and productivity improvement that need to be made over the coming years. This study is doing a safety and productivity analysis of some 40 vehicles from ten countries including Canada, the U.S. and Mexico so we can see how our relative fleets compare. The comparison is not only in terms of the performance measures I just spoke of, but also things like the productivity of the vehicles, the mass of the production of the CO2 of the vehicles, and the fuel consumed by these vehicles. We can see very effectively how size and weight regulation influences global efficiency, and the efficiency of independent countries. Broken into the general classes, the workhorse, high capacity vehicle, and the third class is a very high capacity vehicle. We looked at these various vehicle options to see how they compare. This comparison really helps instructs us on the effects of regulatory measures, and how they influence vehicle behavior and transfer productivity. The study also offers some possible regulatory and operational improvements to take us to the future of transportation. Now this study happens to be part of an international conference that we're holding at the University of Michigan on June 15, 16 and 17. We'd love to see you all there. It's a great forum because we want to experience what has been happening internationally and to see what might translate in to the U.S. It gives us a good sense of where we're standing in relation to the rest of the world. It's very much a combination conference workshop. The input from knowledgeable people such as yourselves would be very much appreciated. The website for the conference is www.magictrucks.org. Love to see you there. That concludes my presentation.
Thank you to John and thank you to those of you who posted questions. We'll address your questions at the end of the seminar. We'll now move on to Tim Lynch of the ATA.
Let me reiterate John's comment; thank everyone for participating and for holding this forum. I'm going to take just a tad bit little different tactic and look at it from the motor carriers perspective and what it means in terms of ability to essentially move the freight. In doing that, I'm going to talk a little bit about safety, about the energy, environmental benefits, meeting customer demands, and then talk a little bit about what this all could mean in terms of what we view at least, as an insufficient infrastructure capacity and something that's not likely to get a whole lot of improvement going forward.
I think probably most of the participants have seen a variation of this map and then the next one, showing graphically, what average truck volume is in first in 2002 and then showing what that is projected to look like in 2035. You can see most of the thinner lines are now a lot heavier. There are a few new heavy lines that were not there in 2002. Again, indicating where some of the major freight corps doors, what we have, and what is projected. The next two slides are interesting. I think in some regard much of the debate on the subject of more productive trucks has been kind of dictated by are we really looking at a zero sum gain. Meaning if we make the trucking industry more productive; does that hurt the railroads? Does it move freight from the railroads back onto the highway? Again, this is essentially putting us in the context of a zero sum gain. We don't think it is a zero sum gain.
If you look at this slide, global incite that has been doing some sort of a rolling study on this subject. If you look at the very top line there, it is projected that rail intermodal over the next 11 years is projected to grow a tad bit under 70%. When they did this two years ago, not only was the rail intermodal higher, most of the other numbers were higher, but obviously with the recession and the severe drop in freight tonnage throughout the country, some of those number haves been scaled back. Again, you can see that the top number, the highest increase in growth and tonnage is going to be represented by rail intermodal. However, even with that growth in tonnage, you will see that the percent of market share and the distribution of tonnage by mode are not going to change significantly. As a matter of fact, truck tonnage market share is actually going to grow at a slightly higher amount in terms of the percent of tonnage. So the point being we have to make sure we're not only investing in all modes, but making sure we're getting as much productivity improvement as we can and particularly geared toward the mode that will continue to be the dominant mode for moving freight in the country.
Now I really like this next slide. I hope everybody else does too. This sort of shows the progression of tonnage, rail versus truck. If you go back to 1950 during the advent of the interstate highway system, you see a gradual move on the highway system. We get into this sort of mid 1970s and you see a leveling off of that. Both modes essentially found their balance. Then we hit into the 1980s. Now I probably should have put another word up under "Just in Time" and "Supply Chain". That word would be deregulation. In 1980 the trucking industry was deregulated and it led to a lot of the innovation. You can see in that timeframe, just the dramatic increase in truck tonnage, and again essentially a flat line or little bit progressing up on the rail side.
Now looking at the next one, this is again, a kind of interesting progression. For those who may not be familiar, class 8 tractor is over the road heavy duty tractor. Class 6 and 7 are next and classes 3 through 5 are more of the smaller trucks and certainly the delivery vehicles. If you look at the projected growth over the next 11 years, you'll see again, the class 8 tractor population is not projected to grow all that much. Yet, if you look at the two lower classes, the 3 through 5 and the 6 through 7 show a significant growth pattern. The class 8 is the over the road long haul vehicle and the classes 3 through 7 are the equipment that move regional freight and more of the local traffic, certainly almost all of the local pick up and delivery. So if you want to go back to what I said earlier about viewing this as a zero sum gain, you look at the growth in those two classes, the 3 through 5, 6 through 7 and that is really short haul pick up and delivery and is the least likely to ever even be considered for any kind of movement on the rail. So I think that one sort of shows that while the growth in class 8 over the road remains somewhat small the other classes are projected to increase rather dramatically.
Let's talk about weight. There are practical reasons why we have a need for Congress to take a very, very careful and thoughtful look at making some changes. APUs - These are auxiliary power units. These are essentially items that allow the truck to operate on just as the name applies. They cannot run off of the main engine, thus save fuel. However, we don't generally think about this, but average auxiliary power unit can weigh up to as much as 400 pounds. We have estimated that the trucking industry has gone through two generations of new engines, will have a third one coming online in 2010. It's projected that the 2002 engines that was required for those new engines added about 338 pounds to the truck. The 2007 engines added another 275 pounds to the truck. The 2010 engines are going to add the largest amount. Now the engine itself is not going to change that dramatically, but the systems will in order to completely reduce NOx and sulfur add 400 pounds. You now have in the span of a decade of the adding of 1,400 pounds by virtue of mandated equipment. Needless to say, a large portion of the trucking population is weight sensitive and this result in 1,400 pounds less of payload. You'll read on the bottom I have California impact. California has come up with essentially their own standards, not all of which has been fully implemented. But they again will be adding weight to the vehicle. For any of you who have seen one of these vehicles out in California, one of the requirements is side skirts. These are sort of metal sheets that go between the front and back wheels of the trailers. Those are going to be adding weight to the vehicle with a reduction therefore in the payload.
This is a comparison of the use of more productive trucks, and what that means in terms of fuel. The first compare a standard tractor trailer, a Rocky Mountain double. The comparison is moving 1,000 tons 500 miles. You can see you are looking over 600 gallons of fuel reduced on just one vehicle. The second compares a double, standard double tractor, semitrailer with a triple. This is moving 100,000 cubic feet 1000 miles. There you see a little over 500 gallons saved on that kind of change. You can see sort of dramatically if you can introduce this in selected lanes the kinds of savings that you would be able to achieve both in terms of fuel use and then of course the resulting environmental an carbon footprint.
When you get into this issue, the fact of the matter is we really haven't seen much change in truck size and weight. Some interstate weight limits in many, many states have remained frozen in time for more than 50 years. There's been no major weight increases in 35 years. We went to 80,000 pounds, 9% increase over the 50 years. As some of you are aware, 1991 constituted an LCV freeze which whatever was permitted to be operated on that particular road in 1991 is all that will be allowed. You cannot expand that to any new roads even within a state that would permit or does permit LCV operations or higher weighted vehicles to operate. This is compounded by the fact that you've got a growing amount of pressure from selected groups seeking some kind of exception from the freeze, logging being probably being the most prominent throughout the country that is looking for changes in that. Now I wanted to give a little bit of perspective on these changes or the lack thereof in productivity.
If you look at ocean intermodal, volume, basically in the last 25 years, the tonnage change or the productivity improvement for ocean going vessels have increased almost 300%. Rail intermodal by volume - this is predominantly presented by double stack. That has seen a 200% increase in productivity. Grain, coal trains, weight, sort of jumbo cars represent about 93% of the improvements in productivity over that same timeframe. That is versus an 18% change in capacity on truck volume mostly represented by the move to doubles as well as the move from 38-foot trailers to 53-foot trailers.
Similarly truck volume saw about a nine percent change in productivity in that same period of time. Again, just taking all of that into one slide, you'll see ocean going vessels with the largest followed by train cube followed by train weight and significantly lower amount in productivity amount in truck cube and truck weight.
Now what are we talking about? When we go through the next series of slides, it's important to keep in mind that virtually everything, well everything that I'll be talking about in the next series of slides, this equipment in one form or another is already operating on some road in some state in the United States. When Congress went from standardizing under the FTAA back in 1982, the standard trailer was 48 feet long. Since that time, and exclusively through state activity, that standard has now gone to 53 feet. Rectify the federal standard and what is the normal single trailer length throughout the United States, throughout the states to 53 feet. We would also suggest that you cap the trailer length on the national network at 50 feet.
WGA harmonization study is trying to harmonize size and weight laws throughout the western states. These were not one or two states that participated, but you can see a tremendous amount of interest in all these states to somehow reach a size and weight throughout those western states.
I'm going to run through a different kind of vehicle configurations. All of these slides, every one of these trucks is already operating somewhere on some road in some state in the United States.
The first is what we refer to as a light Rocky mountain double. Maximum trailer length of 81 feet is broken up with a trailer between 38 feet on to 48 feet on the front and 28 feet on the rear. Another form is what we refer to as the heavy intermediate length double. This adds several Axles operating from nine to 11 Axles with 129,000 pounds. These are restricted today to the national network. The long doubles, or what's generally referred to as the turnpike double, have nine axles with either a 38 foot or 58 foot twin trailer configuration. This one actually restricted to interstate highways. It's for those who don't realize the interstate system is a significantly smaller network than the national network as currently defined.
The configuration that most of the LTL world and the package world is looking at would be the triples. This configuration has three 28.5 foot trailers maximum with GVW of 110000 pounds. The use of these triples is restricted to areas off the interstate or on the interstate where the vehicle would come in, uncouple the third trailer, take the two and then another piece of equipment would come out and pick up the third trailer.
On the single trailer on the weight side, this would be maintaining the current federal axle weight. This is the legislation that the congressman from Maine has introduced. It would essentially permit the type of vehicle that's described there. The benefits are similar operational characteristics to a five axle.
One of the key issues in Maine is shifting heavy vehicles from local roads to where they're permitted to where they're not currently permitted. Getting those vehicles off what in many places are two lane highways or two lane roads going through highly congested local communities. LCV operations beyond the western uniformity would be on a case-by-case basis lifting the 80,000 GVW cap and allowing this equipment on a case-by-case basis and possibly including on the doubles 28 feet to double 33 foot trailer. The FHWA did the size and weight study the single largest productivity gainer was the double 33 foot trailers. That configuration is only used in the United States and very limited agricultural operations. If you went from 28.5-foot trailer to a 33, that would necessitate a change in the actual trailer equipment.
We all think that we're buying lighter cars so therefore they can get more of those onto an auto hauler, but believe it or not the hybrid vehicles are weighing significantly more. Because of this, there is a consequence to the auto haul industry. They are being hurt by the inability to permit hauling more.
This tries to bring the idea home directly. In a steel hauling operation, as you've probably seen these on the highway there is a flat bed hauling two steel coils. You'd have three of those vehicles hauling six steel coils or if you could go to higher weights with the added axles you could be hauling three steel coils per trailer and eliminating one of the trips for that type of an operation.
Let me close with a couple of very real world examples. International Paper testified not too long ago that on one service lane out of their Courtland, Alabama plant they could reduce the number of trucks from 600 to 450 per week. Five million less pounds of truck weight on the highway per week. Kraft foods could reduce 2,150 trucks loads per year to1650. Again, 312 miles, 33,000-gallons of fuel and 750,000 pounds of CO2 can be saved when using heavier trucks. Finally Miller Coors would be able to reduce 2,473 trucks per week; a reduction of 25%. They will also have well over a million fewer vehicle miles per week; a calculated fuel savings of $90,000 per week. A few other savings are four million-pounds of reduced CO2 emissions and 86 million pounds per week in reduced wear and tear own roads and bridges. That brings me to the end. Thank you. We'll await your questions.
Thank you Tim. Our final presentation will be given by Mark Swanlund of the FHWA Office of Pavement Technology.
The benefits of heavier trucks on the nation's highways, specifically the interstate that we have heard about today also have a cost. I'm going to talk about the costs. So this is my outline of my presentation, I'm going to cover a brief description of where we're are today, and what is causing infrastructure damage to roads and bridges. We are going to compare the 97,000 pound six axle configurations to the 80,000 pound five axle trucks. Tim talks about different configurations, but our analysis was limited to looking at one type of vehicle. We will also look at it from a constant payload basis. We will also talk about the limitations of our analysis. We are limited by time and resources and will talk a little bit about what you can and cannot extrapolate from our analysis.
What causes damage to bridge infrastructure? Heavy loads, axle spacing, and axle weights are the biggest factors. The same axle weights and axle spaces will have a different impact on different types of bridges depending on the material and the configuration of the bridge. There are many different types of bridges; not just concrete and steel. The different lengths of the bridges allow those bridges to respond differently to the same type of trucks. To give you a sense of the issue, there are 55,000 bridges on the interstate system of approximately 44,000 miles or so. There are about 116,000 bridges in the national highway system which is around 160,000 miles. There's a mere 600,000 bridges on all the public roads in the United States. There are a lot of different bridges, and it's very difficult to make generalizations about how a heavier vehicle will impact bridges in general because there isn't a general bridge. So the only way to really determine the true extent of impact of a heavy vehicle on the nation's bridges is to analyze each bridge. Pavements are simpler because asphalt and concrete are predominant materials for pavements, and the factors that influence how trucks influence them are pretty much the same whether you have a concrete or asphalt pavement. Axle weights are the most important part of what impacts pavement. Axle spacing and total vehicle weight are not as important. We are able to do a little bit of an analysis on how heavier trucks have on the different pavements.
This is a graph of an axle load distribution, national average database that we have from our long pavement performance program. On the left hand axis we have load distribution and on the horizontal axis we have axle load in thousands of pounds. The break line is drawn at 20,000 pounds. All of the axle loads to the right of the break line represent approximately 2.4% of the total single axles out there on a national average that are heavier than 20,000 pounds. Notice, out at the 30,000 pounds and higher, you can barely see the little bars, but those are significant when I show a little bit in the presentation. So rule of thumb here is 20,000 pound axle represent two percent of the traffic. Looking at the tandem axles, we see kind of the same thing. A lot of tandem axles are relatively lightly loaded. The same type of chart for tandem axles indicates that 13% of tandem axles are over 34,000 pounds and only 4.7% are over 40,000 pounds. Notice how few and how short the bars are of the 60,000 plus pound tandem axles.
If you look at the effect of those axles, this chart is the same on the horizontal axis, but the vertical axis is the relative damage contribution of those axles. The higher the bar is, the higher the axles that are out there on the graphics contribute to the total damage to the pavement. With bottom up cracking for concrete pavements above 40,000 pounds, they only represent five percent of the traffic by are doing 80% of the damage. Weight is very important. Axle weight is very important on pavement damage. Looking at top down cracking pavements, five percent of the traffic is doing about 35% of the damage. This is just another type of stress an axle does to pavements.
This is the same information presented in a pie chart. The numbers here continue align exactly with the previous graphics because it's a combination of top down and bottom up cracking. The axles less than 34,000 pounds are doing about a quarter of the damage, and the ones between 34,000 and 40,000 pounds are doing about 17% of the damage. Axles weighing less than 34,000 pounds are about 88% of the total traffic. You'll notice that the tandem axles greater than 40,000 pounds are only five percent, but again this is the same chart, they do 58% of the damage. There's a lot of damage done but relatively few axles out there.
There are three configurations we looked at on the impact of heavier vehicles on infrastructure, particularly pavements. One of these configurations is the 97,000 pound axle truck. Because of the physical limitations of adding an additional axle to the back of a trailer, assuming that every additional pound that you add to the trailer is going to be carried by the axle there, there are some physical limitations that are probably unlikely to be adopted in that situation. The different configurations how that axle can slide will change the center of gravity. We have three configurations here, and one is with a 41 foot wheel base. We looked at a 7.5 foot overhang and a 6.5 foot overhang. What that does is essentially change the weight distribution on the tandem. If you made an even distribution of your load, you'll end up with 40,000 pounds on the tandem axle. If you remember that on the previous slides, they do a lot of damage in comparison to the 40,000 pound axle. Those are the higher productivity or heavier vehicles we looked at.
How heavy vehicles can impact bridges. Bridges are currently designed to meet AASHTO design standards. Bandages were made for the older design. One axle is 14 to 30 feet apart. Alternate military loading is two axles weighing 24,000 pounds. The bandages were designed for a vehicle like this. Typically bridges are based on these standards and are built designed with the significant factor of safety. So any adjustment, increasing the loadings above the standards above these levels will increase the stresses on the bridge and have a negative impact. New bridges are designed to meet what's called HL-93 loading. The load resistance factor design standards. There is a little less impact on some of these newer bridges. The older bridges represent a tremendous amount of inventory. There's 55,000 bridges in the interstate, vast majority were built in the 1950s, 1960s, and 1970s. They were built with this older design standard.
So if we increase loads on bridges, what will the results look like when was use a 97,000 pound six axle truck. It will increase stresses and as a result reduce the expected service life or decrease the safety factor. Sometimes we need that entire safety factor and more. This can be seen based on experience from a short while ago in Minnesota. We would expect higher maintenance and repair cost with your trucks.
Again to determine the exact extent of bridges that would require strengthening or replacement of the interstate by deployment of 97,000 pound, six axle trucks would require an analysis of each bridge individually. We would have to consider the specific design of that bridge and the condition of the bridge and its bridge members.
Pavements are a little simpler. We have a graphic here that is somewhat of a simplification. It looks at the relative damage or stress on a jointed concrete pavement. It shows a red line labeled single axle and blue line tandem axle and another line labeled tridem axle. The slope of those lines represents the relative damage. The bottom axis is the load; the vertical axis is the relative stress. The baseline here was the stress on the pavement of a jointed concrete pavement. We have it set up so a jointed concrete pavement would give you a relative level of one. A tandem axle with 44,000 pounds or so with a load on it would stress the jointed concrete pavement the same way. You can go up as high as 81,000 pounds with the tridem axle and get the same loading. If you looked at this a different way, basically reading across with the loadings at the 0.7 relative stress, it would be about 11,000 pounds on the single, 23,000 pounds on the tandem and 43,000 pounds on the tridem. You can put a lot more weight on the tridem and have much less damage to the pavement. That's the take away from this particular slide. The more axles allow you to spread the load over the better.
Asphalt pavement responds differently to heavier loads. On concrete pavement, the most severe loading is two axles either side of the joint in the concrete. You can get a lot more bang for your buck by putting the load on the tridem as opposed to the tandem or the single. The 38,000 pound drive axle and the 40,000 pound drive axle, the 40,000 was with tridem axles pushed all the way to the back. This is a relative damage, a 97,000 pound six axle truck relative to an 80,000 pound five axle truck. Limit the tandem to 37,000 pounds and you get the same relative damage on a truck by truck basis. If the tridem axles are pushed all the way back for concrete pavements it results in a 40,000 axle, two times the damage with a 97,000 pound truck compared to the 80,000 pound truck. The question you might ask is this a truck by truck analysis. Assume that there's going to be fewer heavier trucks out there, you'll notice that the same configurations with the reduced number of trucks, the relative damage is essentially comparable for both the first two configurations we talked about. There's still significant additional relative damage provided by the heavier trucks when the tandem axle can get up to 40,000 pounds.
So what are the limits of our analysis? We did not assume any change in our loading patterns. We did not make any assumption about a modal shift if, for instance, rail freight would move to the highways and trucks or the barge traffic would move to tracks. We also didn't make my assumptions about the way the facilities are utilized. That means in some states, weights higher than 80,000 pound five axles are legal off the interstate. We didn't assume that if relative to higher weights were legalized on the interstate whether a bunch more heavier trucks that are running currently off the interstate would not shift to the interstate. These are now operational aspects that infrastructure engineers didn't consider. Also the bridge impacts are estimated. In conclusion the 97,000 six axle trucks will have an impact on infrastructure. The impact on pavement can be minimized if the loads on tandem axles are limited 38,000 pounds. For bridges, we estimate some bridges will need strengthening and replacement, but the exact extent of that strengthening and replacement will be on an individual analysis once a heavier configuration is determined. That is the end of my presentation.
Thank you Mark.
I'd now like to start off the Q&A session with the questions posted online. Once we get through those questions, if time allows I'll open up the phone lines for questions. Mr. Woodrooffe. How well do LCVs operate in windy conditions?
That is a good question. I do not know the answer to that other than to say that they are comprised of separate vehicle units so you would think they would be similar to independent units should they be rolling down the highway. As a substantial risk, I do not know.
How do LCV safety characteristics differ for rural vs. urban roadways?
We saw in the study in Alberta that we are seeing gains on both kinds of road networks. There was not a lot of difference between the two. Obviously the divide highway produces a must better crash rate, but there was not a lot of difference between the two.
It would be good to see some comparison of the benefits with the costs associated with LCV operations (for example, costs associated with equipment, staging areas, etc.)
That is an important consideration. We have just completed a study for a national private truck council. We have been looking at LCVs to see what they would have on the business case. With staging areas there is an additional cost, but when it is put over the entire operations, the affect is minimal.
Have you discussed your HPV study findings with the FMCSA?
I have had conversations with the FMCSA. These are presentations I have given in the past.
How do A, B, C trains perform in windy conditions (blow-overs)?
That again is an area of very rare occurrence. Any vehicle is vulnerable to that. Roll coupling will assist in that in blow over risk.
Professor Woodrooffe, can we have more detailed data on human factor (good drivers) to supporting the arguments for LCV? How do we go against safety constituents fighting against LCV's?
I think the driver performances is the most important element. The policy issues that I was talking about were aimed at the driver. For example, there were minimum service requirements before one can graduate to LCV. We see triple trailers operating in certain parts of the US and they perform extremely well because they have a certain type of driver. There is some discussion of the type of vehicle heighten the drivers awareness. What we need to do is find which really matter.
A number of U.S. states have grandfathered LCV operations. Is it known how many LCV operators are in the U.S.?
I am not sure I understand. How many are US based truck companies? With respect to some of the western operations, I expect you have some Canadian companies that are operating some form of the LCV across the border. I am not familiar with who holds types of permits on the Indiana turnpike and such. I am not sure if there is an equivalent in Canada. A comment on the wind, in almost every state that allows triples to operate, they have restrictions to weather and companies are notified to stop operations in poor weather.
Mr. Lynch. Mr. Swanlund. FHWA vehicle classifications numbers for all vehicles range from 1 to 13, 4 to 13 are trucks, 8 to 13 are commercial trucks. The ATA has a different classification scheme. Is there a document that shows a conversion chart from the FHWA scheme to the ATA scheme, or vice versa? Is there a way to convert the ATA vehicle classifications scheme to the FHWA scheme, or vice versa?
I am not familiar with the conversion. Maybe colleagues in the freight operations office can answer
Tom Kearney (FHWA):
The questioner is referring to the F-scheme, an approach for classifying traffic based on the number of axles. There is no direct conversion over to the scheme that Tim showed that I'm aware of. The scheme that Tim showed has to do with horsepower of the tractor and the operations of the truck.
What is the unit that you are using for damage? Is it based on repair or some other unit?
It was based on stresses.
Explain how an 80 kip tridem causes less damage than three 20 kip single axles.
The example which is used was on joining concrete pavement with joints. The most severe loading is with an axle on each side of the joint. Any load on the middle of the slab does not do really any damage. It is mostly about the stresses by the joint. An 80,000 pound tridem is really two 26,000 pound axles on either side of the joint, and the last is near the middle and does not affect the pavement. This is how very high tridem loads can be equivalent to other tandem and single loads. It isn't an exact translation, but that's how you get that extrapolation.
Tim, have you done any analysis on additional tractor weights for diesel-hybrids or LNG's. PACCAR indicated to me that a LNG engine tractor weighs 1,100 lbs more then the same tractor with a diesel.
I think I have seen that same number. A lot depends on the size of the tank and therefore the kind of operation. If you are looking at the tradition long haul operation, it is significant, but if it is a local pick up and delivery, the weight will be significantly lower.
Mark - How was pavement stress measured? Where were the tests conducted, in what climate and how the vehicle weight was measured?
Stress determined on an empirical design guide. The loads were at different points on the pavement. We made assumptions about climates and materials properties. They would not apply to all places, but are pretty general.
What data is an available comparing effect on safety, noise, congestion (beyond VMT reductions)?
Well, we have data that is sort of around the crash rate, so that is more than just VMT. We have hard data about miles travel out of certain jurisdictions.
I would urge you to attend John's conference in June. This conference focuses on a comprehensive study conducted in Europe investigating the implications of increasing truck weights from various aspects: energy consumption, impact of environment, pavement and bridge damage. I do not think a comprehensive study of this type has been done yet in North America. The European Study is a very comprehensive study. John will be hosting the Workshop presenting the findings in June.
One of the challenges is in the western states which have let the equipment operate for so long without breaking the data out.
That's correct. Part of the limitation is we didn't have good VMT data tied to those. If we ever thought as a safety community or transport community of one thing we could do better, that would be it. I think that part of the fear is the unknown, and people just don't appreciate what these differences are unless we can document and qualify them. It's a difficult position with safety case.
On slide eight, would the shift, or growth in intermodal rail related to the change in class 8 growth?
Again, there will be an increase, but the bulk of the increase will be in short haul and local delivery
In this age of electronic verification and safety checking at weigh stations, there will be more additional costs to the states to implement larger vehicles traveling through the states. Is there intent to look at a total cost picture to allow larger vehicle travel?
Well I had a slide on a model for economic costing for this, and one I think with the evolution of electronic communication of vehicle to vehicle, you would think that a lot of this could be set off on an automatic basis. I would hate to see this type of system being some sort of a burden but you would have to offset some of these costs with the big picture. Some of these costs are in the intangible column, having to do with emissions and having to do with fuel supply and others. The cost model should be comprehensive to address all of the intangibles.
All right, thanks. Now before we close it out, we have a quick announcement from Tony Furst who is in the room with me. I'll hand it over to Tony to make his announcement.
Tony Furst (FHWA):
Thank you. Thanks to the three presenters today. It is always intriguing that these webinars go over the allotted time. This subject matter is one that resonates with an awful lot of people. Quickly for everybody, the economic recovery discretionary grant program was announced by the department Monday of this week. There is a period of time where you can comment on the grant criteria. Those are due to the docket by June 1st. Applications for receiving funds are due to the department the 15th of September. The website that we have listed here is where you can pull down the information that you choose to. This is an FYI that it's out and available for public comment and the doors open to accept applications. The next slide is a FYI for the community as part of the career professional development logistic courses in freight professional development. Rather than do that since there are so many logistic courses available through a number of universities and institutions. Instead of we put together a scholarship program that enables you to take those courses at other universities. We'll meet you half way by providing 50% of the cost. The applications are due by June 12 for those interested. We'll screen those and choose from those who apply. Of course there's a website if you want to pull down the information regarding the university grants. This is a new facet of freight professional development and we wanted to use this venue to get the information out to as many people as we could.
The next seminar will be held on June 17 and will be about Climate Change.
Enjoy the rest of your day!