View the September 21 seminar recording
Nicole Coene
Good afternoon or good morning to those of you in the West. Welcome to the Talking Freight Seminar Series. My name is Nicole Coene and I will moderate today’s seminar. Today’s topic is: Accommodating Trucks in Innovative Design Intersections and Interchanges.
Before I go any further, I do want to let those of you who are calling into the teleconference for the audio know that you need to mute your computer speakers or else you will be hearing your audio over the computer as well.
Today we’ll have three presentations, given by:
Jeffrey Shaw serves as the Intersections Program Manager for the FHWA Office of Safety. His focus is on programs, projects and products of National interest that are intended to enhance intersection safety for all users. He is a registered professional engineer in Illinois, and has been board certified as a Professional Traffic Operations Engineer and Professional Transportation Planner. He currently serves as co-Chair of the TRB Intersections Joint Subcommittee and is a past Chair of the ITE Transportation Safety Council.
Gil Chlewicki is considered an international expert on innovative intersection and interchange designed. He has introduced seven innovative designs in published papers including the Diverging Diamond Interchange, which is growing very quickly in popularity in the US and abroad. Gil has worked on many types of innovative geometric designs from the conceptual planning stage to final design. He has also been teaching and researching on innovative designs for many years.
Hermanus Steyn is a Principal Engineer at Kittelson & Associates, Inc. and has more than 23 year of experience in a variety of transportation studies, designs, and construction for all types of roadways—from local streets to freeways. On such projects, he considers trade-offs from multimodal perspectives based on the project context (e.g., rural, suburban, and urban). In addition, Hermanus has extensive experience designing at-grade intersections including conventional intersections, modern roundabouts, and alternative intersection / interchange designs. He understands the interaction between geometry, operations, and safety, and considers and analyses trade-offs to development community-based solutions. He is a member of the TRB Geometric Design Committee and the Intersection Joint Subcommittee.
Keith Smith is an Environmental Engineer for the Ohio Dept. of Transportation. He has been with the Department for 25 years doing Environmental and NEPA compliance as well as Project Management. He is a Professional Engineer with a Bachelor’s Degree in Civil Engineering from the University of Cincinnati. Keith has been the Project Manager for the Greene US 35 project since 2010.
Brian Toombs, PE has been with Burgess & Niple for over 18 years. As B&N’s nationally-recognized Diverging Diamond Interchange (DDI) expert, he was the project manager and lead roadway engineer on the first DDI in Ohio, as well as a lead roadway engineer on the first DDIs in Indiana and Michigan. In all, he has been involved in nine DDI projects that are either currently in design or have been recently constructed. In an effort to assist other DOTs so that their DDI designs are as efficient as possible, Brian has given numerous DDI Lessons-Learned presentations across the country drawing largely from his DDI experiences.
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 chat area. Please 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. If time allows, we will open up the phone lines for questions as well. If we run out of time and are unable to address all questions we will attempt to get written responses from the presenters to the unanswered questions.
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 few weeks, along with a recording and a transcript. I will notify all attendees once these materials are posted online.
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I’m now going to turn it over to Jeffrey Shaw, FHWA and Gil Chlewicki, Advanced Transportation Solutions to get us started.
Jeffrey Shaw
Thank you, Nicole. I’d like to point out that the content of these presentations have been developed our members and friends of the TRB intersections joint subcommittee. Everyone attending todays webinar, if you are looking for opportunities to get more involved in the Transportation Research Board activities among them is the next opportunity to do that. We have several topics including operational effects, geometric assign, access management, pedestrians and others. So, if you are looking for an opportunity to get a sense of what’s going on in that part of the research world, we certainly invite you to attend our meetings.
With that, I would like to provide a brief overview of why innovative intersections are being presented at today’s webinar. As many of you probably have heard over the years, FHWA has been evaluating researching and promoting different forms of innovative intersections for many years. In 2013 and 2014, we actually made a specific list of innovative intersections that are part of our everyday counts innovation program. As one of the safety technologies, the specific innovative intersection that we promoted to do that was the Every Day Counts initiative which included roundabouts, median U-turns, the displaced left turn, the restricted crossing U-turn, and the diverging diamond interchange.
Why did FHWA choose to focus on EDC initiative on innovative intersections? As I mentioned, it was a safety technology and the reason why we decided to focus on that is because about 25% of all of our traffic fatalities across the United States each year occur at or are related to intersections. If we expanded the scope of that analysis to include all of the crashes where people are hurt, injured or worse that’s about half of all the severe crashes that occur. We know intersections are a major safety challenge. In 2015, we saw the number of fatalities increasing in the United States by over 9500 people who were killed at intersections. This is a significant part of the safety challenge that exists in our country. But at the same time, it is also an operational challenge. We know that intersections become bottlenecks along high-volume roadways, and so that combinations of intersections are both the operational and safety challenges are very ripe areas for us to be working on together.
Here are some other pertinent intersection safety facts: If you look at angle crashes where vehicles coming from different directions are crossing paths, and if you look at left turn crashes where a left turning vehicle is crossing over the path of an opposing vehicle, if you combine those two types of crashes you’ve got nearly 2/3 of the fatal crashes that occur at intersections. One of the key aspects of innovative intersections is how they address a left turn – and in many cases how they handle tossing path type conflicts. Additionally, we know that intersections are a challenging area for non-motorized users such as pedestrians and bicyclists. Even at signalized intersections which we are all very familiar with, and even as people walking or biking across intersections we know what to expect as to the last intersections even there, 25% of the pedestrian bike mentalities occur at signalized intersections.
The reason why innovative intersections are particularly attractive is because of the safety benefits. Fewer severe conflict points when we talk about innovative intersections are one of the things that we typically look at is how to spread the conflict points apart. How to make those conflict points less severe in terms of the angle of the crash or the speed of the crash, how to make the decision points for a driver or for somebody walking or biking through the intersection, and how to make those decisions simpler. This also is a secret ingredient to innovative intersections and that is because of the geometry or synchronized operations of the traffic control devices intended to get speed management. Even while traffic might be moving more slowly through the intersection, we are actually achieving a higher throughput of vehicles and people through the intersection. All this translates to significant crash reductions. If we are talking about roundabouts, that’s in excess of a big percent reduction in severe crashes ago after talking about the virgin diamonds or restricted crossing U-turns, we’ve seen consistently in excess of 60% reduction if the severe crashes. These are really, really effective treatments for safety. But they also have great mobility benefits and great operational benefits. It is inconsistent with actions in in the late and congestion for all users at an intersection. We see increased opportunities for convenience for pedestrians and bicycles and all this has been fits across the board to all users including freight. And finally from the standpoint of the agencies try to deliver these projects, innovative intersections often present opportunities to minimize the footprint, maximize the operational aspects and basically decrease construction costs, ongoing maintenance, and operation costs – all this leading to best value options for state and local highway agencies.
We cannot cover everything in the course of one hour, but we have developed a lot of great resources through these efforts over the years. I would like to direct you to two resources that after today’s webinar you might be tempted to visit. One is our FHWA YouTube channel where we have several videos and studies focusing on the specific types of intersections. The other is our intersection safety webpage or we’ve got lists of outreach and education materials in our research from federal and state and Transportation Research Board, and just a whole host of different resources that you might be interested in for all these innovative intersection types.
With that I would like to turn it over to my partner, Gil Chlewicki, who will walk us through the specifics of a few of these intersection types.
Gil Chlewicki
Okay, thanks, Jeff. What I’m going to do in the next 15 minutes is go through some of the innovative intersections that Jeff mentioned, and go through basic ideas of how it works and some of the issues we are dealing with in terms of trucks and the design of these intersections.
Let’s start with the restricted crossing U-turn intersection which is what Federal Highway calls the super Street turn. As Jeff mentioned, this has great effects in terms of safety for the un-signalized version also for the signalized as well and it is very difficult to judge how to get across the other side. It is a lot of severe accidents, fatalities happening over here and it is very automatic as trucks stick out of the median, it’s no man’s land and the J-turn solves the problem in that respect.
When we designed these, it is important that we address trucks and the big issue for us terms of these designs is in this picture we see a truck making a U-turn on the super Street in North Carolina and see that the shoulder is wider to accommodate the truck.
We do have different charts to give us an idea of who would be required for the U-turn movement design and if it would be close to see the turn to 40 feet wide so that a bus would be able to make a turn at the shoulder, but any a larger vehicle would be not be able to make that move completely. It has to be wider so that we can accommodate more movements over 100 feet and all of our vehicles would be able to go to the inside lane.
If we don’t have enough room on our roadways to accommodate the traffic of the future, it doesn’t mean we cannot design where the truck will be able to use this about to complete the U-turn movement. You see on the chart over here some cases we have a double U-turn. We try to accommodate as much as possible to trucks, and in these cases we designed just enough so the U-turn is signalized because there’s no lane for merge for the U-turn. So the vehicle would come in and come back into the lane. At the bottom you see there are cases for un-signalized where the U-turn would go into an acceleration lane to the right turn lane. In many cases the U-turn is going to maneuver for a lot of vehicles switch result in the right turn in and increase the movement.
There are few cases where certain trucks cannot go in both lanes in a double U-turn. Here’s an example in North Carolina we have trucks restricted only into the right U-turn lane because in this context we don’t have enough room to accommodate a big enough lane for both trucks. This is the case of the make U-turn and the right turn into the side street that would be no problem, but if they were doesn’t want to go straight where there would be able to make a maneuver so some things to consider based on context, is to help the operations are handled at that location.
The idea is you don’t want the turns happening at the main intersection. If you are on the major road you have to go straight past the main intersection and an update to make U-turn and make the right after that. if you are on the side street you have to make a right turn at the main intersection, go to the median five U-turn and come back in the other direction. The difference here is allowed in it left turns are played limited and you have to use the median for the U-turn.
Some places like Utah where they don’t have a wide median or median at all, they use the concept but they call them a different name, the call them U-turn or through turn in Utah and other states have different names as well. Because they don’t have a wide median they have these lanes to allow the U-turn in and they design the lanes to accommodate with a design vehicle was.
This is a very powerful intersection in terms of operations because it gets a left turn out of the conflict with the through movement in the way advance the left turns happen prior to the main exception and able to go the same through movements. You have the through movements going to major road and the left turn will actually stack up over here. After the left turn just after the through movement happen for the Metro the site through will get the left turn and get to movement and towards the end of the through movement this left turn will start traveling down over here and approach a red light. But the time they get to the red light the design correctly that should turn green and make the left turn [Indiscernible] the time the movements get over to this left letter intersection over here, we will be able to get the green light as well. The idea of the continuous flow intersection is what to give first realize if it is designed quickly should get continuous flow to the rest of the intersection. At Federal Highway is calling these designs the same thing. Across the country we have several dozen states that are starting to grow in popularity because they are very efficient intersection.
In terms of trucks, the main issue we have is really with the left turn movements. The problem we have is making sure that the type of turn with reverse curve is handled so the trucks stay in the respective lane. You see the red through going east bound that’s going straight but the left turn goes into a reverse curve maneuver. Again when we get to the left turn at the main intersection the left turn is tied up so we need to make sure we designed properly for the trucks to be able to go both lanes.
Last design is the Diverging Diamond Interchange and most of you heard of DDI by now. The basic diamond interchange, from the cross street from the arterial it is different. What happens is as you are approaching the first ramp, you will come to a traffic signal where you cross over to the opposite side of do the road so you go over the bridge or under the bridge on the left side of the road and when you get to the second ramp will be another traffic signal. The reason why we do this is because you are the left side of the road on the freeway and off the freeway.
These are getting a popular run in the country. We have 70 across the country right now, and there are several others abroad. You can see half the states now are in great they have a DVI at least one DDI if you travel in North Carolina, Missouri, Utah, and the other states.
In terms of designing for the trucks and freight typically we do design and make sure we accommodate, and the design speed is going to be 25 to 305 miles per hour power going to the cross over, angle is and where from 25 to 50 degrees and we want to make sure the angle path for each truck is not going to the adjacent lane.
There will be times where we will design these shoulders so that vehicles can stay in the Lane with a regular width. You see the stuff to the crossover of reverse curve, you see it as well on ramps so a double left turn and we have a lane in the middle so the truck track even notice we have it on the shoulder we have a wider shoulder part truck driving as well. These ramps can be very tight so aside for the trucks is very important. For the most part, DDAs are being designed very well for trucks. I think I will give it back to Nicole.
Nicole Coene
Thank you, Gil. We will now move on to Hermanus Steyn, Kittelson and Associates.
Hermanus Steyn
Thanks, Nicole. I just want to say good morning. I will provide a big picture with a lot of focus on freight and what we’ve done in Oregon, along with some of the conventional intersections. But first I want to thank several Oregon Department of Transportation staff that has been helping me put this presentation together. It is a great group of folks who are helping put this together. In the presentation there are a few things I want to highlight. There has been a lot of cooperation between the freight industry and Oregon Department of Transportation as well as the local agencies. Some procedures that we put in place from the statute and rules perspective. We will have some intersection examples that are more focused on traditional intersections, and of course we have some interesting challenges when it came to the implementation of roundabouts. And then of course when you to look into the future and see, what are some of those challenges that we may have in the future that we want to address.
One of the bigger challenges like many other states is when you have to accommodate some of these oversize loads. There’s an increasing demand, and as you can see with some of these pictures; on the top left is water filtration equipment that came through here on one of the highways and on the top right. This takes a lot of coordination. So, in Oregon we try to be very innovative, or at least proactive, when it comes to some of these oversize loads.
On the eastern part of Oregon, and also up into Washington state – that are shown here – large pieces of equipment that’s being transported by oversized trucks. So, what did we do? There’s a lot of activity and collaboration and eventually there was ORS 366.215. The Oregon Revised Statute really tries to make sure that we take a proactive step and try to identify to not permanently reduce the vehicle carrying capacity for identified freight routes. There are exceptions to this, and as always, when we look at these transportation improvements is to really try to provide that balance between design, operations, and safety, as Jeff said in the beginning of the presentation. But again, when you need to make sure that freight movement are not unreasonably impeded, so the challenge is communication since it is important to talk about this at the start of a lot of these projects.
Vehicle carrying capacity wasn’t specifically defined with these rules in the beginning, but it is the physical space for a truck. You see at the bottom left photo is a normal truck, but there are much larger vehicles that are coming through, and even to the extreme, as shown on the right side. In Oregon, we have this phrase called “Hole in the Air” and that’s what we try to protect especially along specific routes.
There are a few things of that I know in an urban setting, you are using these tools like, channelized right turns, medians for pedestrian refuge, and curb extensions. If you want to try to make sure that the crossing distance has that multimodal perspective, it is so important to these urban areas, but we also need to understand that they have an impact especially on these freight routes, so we need to take those into account.
What we’ve done is through this ORS 366.215 rules we’ve established in Oregon that we need to make sure that these oversized trucks can go along those roads and that lead to some innovations and great opportunity for engineers nowadays to think outside the box and really see what we can do. The next few slides what we are going to do is really look at some of these treatments and try to collect some of these trade-offs between the different users.
Before we go into the examples, some key aspects for the freight are when we have construction along these routes that we’ve identified within Oregon. The picture on the slide shows where we are building an underpass under an existing expressway and there were many ways of looking at alternatives and ways to accommodate traffic doing construction. At the end of the day, as you can see there’s a big hole in the picture on the expressway with a lot of cooperation with the freight committee, as well as the community, we came up with the solution to close the expressway for four days where we could close to the roadway, and could slide into place. It is that understanding of how we may impact the freight as well as the community. But as I mentioned in the beginning, it is collaborative, and communication upfront, and really trying to find the balance between the pedestrians, bicycles, the transit and freight. The other thing is that sometimes we look to understand the vertical components as well as again for the freight community, really try to identify those key roads.
Between barriers, we want to make sure that we try to protect and provide accommodations for a wide range of trucks. But if we do exceed that dimension, there are special permit that we apply for. In this example, we actually installed removal medians, so if there is a request for a special permit for an oversized load coming to through they need to work with the local district office and they can remove the median at that situation.
Another example is, these are a couple of intersections in the next two slides that were more in a downtown area, but unfortunately it provides access to the port, so there is a need for trucks to go along these routes. You either design for trucks or you accommodate trucks. What we mean, is that they pick to either to use more pavement and space out there and go into adjacent lanes because this is a key route. This was a way to design for it and then you can see on the inside of this turn there is a concrete truck apron and a spot that the trucks can go over. The next intersection, again I know there are challenges with the pedestrians, but the cars will stay off the truck apron at least then we can accommodate the trucks going through some of these tight intersections in an urban area.
This is another example in Oregon, where we have this southbound major movement and it provides access to an industrial area, but it is also in the corner of the intersection with some commercial uses on the other side. So there is an opportunity to make sure that we slow the vehicles down going through the right turn, but again we accommodate for larger trucks to also go through this intersection.
Another improvement in Oregon are the major improvements at this interchange, and one of the major intersections close by also is providing access to a truck stop. Many other industrial areas you will see a lot of the inside curb returns that provide the truck apron.
Of course some of the challenges we had from roundabouts perspective. The freight industry in the beginning had many concerns about multilane roundabouts that go and sideswiped with vehicles. In the top right photograph, you see a car would try to pass trucks within the roadway, so that problem was identified and then we developed rules, because in the past the trucks are often on the losing side, so that was a proactive thing that we try to do here in Oregon.
There were many more questions about trucks and roundabouts. So what we did in Oregon was actually a push for roundabouts for a long time, and really that provides a lot of emphasis on collaborating between the freight committee and the designers. Since then, we have designed several roundabouts. We had a full-scale test at a couple locations where we sent various combinations of truck and trailer combinations that were 130 feet. We can tell you that all those made it through, so this is in a fairground with the cones represent the curb lines and the sandbags present the truck apron. We have another few slides where this is a truck that is pulling another truck through the roundabout. On the top left is 14 feet wide truck. But again, through this field testing we gave the trucking drivers as well as the freight industry comfort when we designed these roundabouts. We also mounted GoPros with different angles on the vehicles so that we can really make sure we are learning from the field testing and how can we adjust our designs. A couple images of the top, the left one is one logging poles about 70 feet long and the top right is a truck that went through – a total of 125 feet. This gave a lot of comfort for the Trucking Association and that led to people embracing roundabouts on the state facilities.
In closing, where we are going in the future is that we have manufacturers that assemble all of the stuff at the factories, but then how do we get that to the construction site itself? I think that is something that we need to address as an industry to maybe start a conversation on. But with that, I will turn it back to Nicole to introduce the next presenters.
Nicole Coene
Thank you, Hermanus. We will now finish out with Keith Smith, Ohio DOT, and Brian Toombs, Burgess and Niple.
Keith Smith
Thanks, Nicole. This is Keith Smith. Today I would like to share with you a project we are working on here in Greene County, which we call the Green Super streets project.
To break down a little bit of the project for you, back in 2000 our regional planning commission and ODOT worked together to complete the Greene 35 Corridor Study because we found this is the last three intersections between Dayton, Ohio and West Virginia about 175-mile stretch that only contains three intersections that are signalized, and they carry about 40,000 vehicles per day about 10% of that is trucks. So we knew we needed to do something to try to make that section more uniform with the rest of the roadway. So in 2007 the project was programmed by highway department chairs patient. We started doing some preliminary studies on how better configure these intersections into interchanges so that we can meet the needs of the traveling public. You will see in later slides do some car dealerships and that sort of thing in the area as well. Do that we’ve developed on the $20 million interchange solution but it is just not unobtainable at this time. We just do not have the funding to be able to proceed and move forward goal a lot of good work has been done and will be our ultimate solution but we needed to come up with an interim solution to still be able to address the purpose [Indiscernible] and that’s the [Indiscernible] terrific trafficking freight through this area and Libya some of the congestion that’s already witnessing. For the freight some of the facts of the freight going to the area looked up it is roughly 24,000 tons of freight per day, totaling about $72 million with product which is going through the signalized intersections of their traditional intersections, the freight it is providing is causing about 20 hours of delay for every peak hour for the trucks, and roughly 100 hours per day of delay throughout the whole intersection for the commerce.
What we’ve done in the past is gone to what we call the transportation review advisory committee; they are the keepers of our larger pods of money for larger projects. We’ve gone to them several times and are requesting for the overall interchange project. As I said before, we just don’t have the funding to be today because of the site to do it right now. So we came up with these interim solutions of the superstreet development to be able to address the needs out there. That’s we needed to determine the funding sources and where would we go from there, what’s our next steps for that.
So, we found when we looked into the Superstreet date to meet our project purpose, they would need to improve our congestion issues, and in order to do that they would need to address some of the safety issues that we are finding out there, and they are considerably cheaper, $120 million solution of the two intersections we will be addressing with this and we are going to be looking at revenue of $5 million per intersection just for the construction cost. This is probably about a tenth the total cost and will give us a really good interim solution and we can pull this together over 15 years or so, 15-20 years possibly. That gives us time to pursue the funding for the final solution of doing the interchange projects out there.
As Gil had gone over, Superstreet is a nontraditional signalized intersection that can carry more capacity than the traditional traffic signals. It does not allow the side street terrific to turn left or to go straight to the main intersection.
Here is a cartoon version of what a Superstreet looks like. It shows the side streets cannot go directly across the main street. Here are some turning movements you will see on a conventional intersection if you want to take a left turn, the right arrow shows that. If you want to make a left on the Superstreet you go down and take a right at your intersection. Take a right and go down and make a left, and do a U-turn. These intersections are even stricter than what other Superstreets where you take a right turn, do a U-turn and come back to make another right turn.
This is a very high level view, and I apologize for the scale on it, but this is the factory and with these were two intersections that we were going to be replacing with interchanges it shows the two superstreet intersections on top of them.
This would be some of the signing you would see, this is a factory road some of the slides show the direction that the traffic has to take to go down and access the U-turn areas. This is a little better view of it. This is actually factory road, and you can see we did incorporate a loop into the side on this because we do have limited right of way out there. You can see the cars parked on the right side for one of the car dealerships. The lanes were designed for a WB-62 truck, which is what we are seeing a lot of out there.
We do have one other Superstreet within Ohio; it is in Boulder County on bypass four. We had similar problems on that bypass them for where we were experiencing nature congestion out there, as there was a fair amount of truck traffic. About four years ago we completed the Superstreet out there and it seems to work fairly well. They are moving a lot more traffic, but it used to take a good 20 to 40 minutes to go from one into the other on bypass, and now it takes about half that time or maybe even less. On the left photo you see the size of one of the Superstreet broken into sections. You see a raised median picture and on the right photo, you see the center aisle to stop the movement but they are mountable just for emergency vehicles.
The bad news for the Superstreets is that we saw higher capacity. Largely because it breaks the traditional signal you see at the intersection and it breaks into two phases so you could dedicate more Greene time to your turn movements. You can also coordinate the signals we found on each roadway in eastbound and westbound they can operate independent of each other, we need to have received a problem on eastbound and then we can adjust just that signal and not affect the westbound movement and vice versa. Then the other advantage is fewer conflict points and reduced delays.
With additional intersections like what we’ve got out there, we can process approximately 30,800 vehicles at the maximum, that’s if we completely gave all the green time. You have to break it down and we can only allow about 60% of the green time on eastbound US-35, so realistically we can process about 2,280 vehicles at a standard signal now on eastbound US-35. With the Superstreet sign we are finding we can process about 82% of the traffic which would bring this up to about 3,000 vehicles per hour, which is quite a bit of an increase. This really helps our capacity and relieves some of the congestion out there. By comparison, once we are able to go with a full-blown interchange and get a facility, we can process of 24,600 vehicles per hour. So, even though we cannot reach that, we still see the 3,000 vehicles per hour which is tremendously better than what we have today.
Here you can see diagrams of the conflict points that most of you have seen before. We do have 302 conflict points to the traditional intersection. Everything from converging, merging and crossing intersections results in conflict points. With the Superstreet, you knock it down to just 14 conflict points and only two of those are crossing conflict points. Which is where your worst accidents occur.
There is 24,000 tons of freight per day moving $72 million of product security 20 hours of delay in the peak hours, with 100 hours of delay. When we reduce the delays, currently we are right now we are experiencing about 203 seconds of the travel time to travel to those intersections. With the total delays running over 100 seconds per vehicle, you are looking at eastbound being around 90 seconds on the westbound. We check to see we look at the reduction on where we are going to get on those, and the reduction travel time was saved up to 22% and the reduction in delay reduced delay by over 50%. Which for the trucking industry time is money since it can reduce the delays in half that is a major change for them.
In summary, Superstreets will provide a higher capacity than the traditional existing signals, not as great as an interchange but still much better than existing. It is like anything, people have to learn it and get used to it. It works really well for us. It does require a U-turn and that’s what makes it work. It would be a considerable improvement over what we have today. And eventually will be able to find the funding to do the final solution, but it will take a bit of time to be able to find that funding and get a good product.
With that, I believe I will turn it over to Brian.
Brian Toombs
Thanks, Keith – I am Brian Toombs. I want to take you 100 miles north from Ohio. This is the existing interchange at I-270 and this is northwest of downtown Columbus, Ohio. The purpose and need for this project was actually for the bridge and to raise it because we had substandard vertical clearance over interstate 270. So I-270 is a north-south route, so with that it is part of the purpose and we are not to widen the bridge. These are two separate bridges carry two lanes in each direction we cannot widen them because it was cost derivative from the safety funding that was in place for this job. That would result in very important points that we will get to later. Part of the other aspect of this project then was to improve the safety of this location by reducing the number of congestion related crashes at the two sections shown here. The amount of congestion eastbound to northbound movement was actually significant – (I don’t know if you can hear me better, sounds like I’m getting request to speak up so I’m hoping you can hear me better now). Anyway, the congestion in the AM peaks a backup of a significant amount – almost a mile at times, and in the PM it peaks the congestion for this northbound actually caused back spill back onto the interstate, so that was a real problem that ODOT wanted to address that they were fixing the bridge. Because this is a freight webinar, it would be good to point out the different truck generators that exist in in the proximity of this interchange. We have a limestone quarry that is out east along Roberts Road. We have a trucker wash, which believe it or not, actually shoveled a significant number of trucks to it. We also have industrial parks in both the Northeast and Southwest quadrants of the interchange. And we have the CSX rail yard there in the South. What you will see is the number of tracks that we have. These are all rail tracks that service this entire region. With the amount of truck traffic that was generated here, the existing traffic counts somewhere in the neighborhood of about 15% of the ADT, which is significant for an arterial. It is not any significant numbers, so what I want to point out on the CSX intermodal rail yard that we saw here, and you can see by the picture below. At any given time you have many canisters that are coming in or out by freight and subsequently, you have roughly that many trucks that are sitting there ready to move those canisters either in or out. This is a significant amount of trucks.
With all that in mind, we started to look at alternatives at this interchange and we started by targeting the congestion issue. That led to some very expensive alternatives as we started to get into the options, and what we saw was a lot of these alternatives that may have fixed the congestion but they also required widening or impacting the bridge which again was cost prohibitive. One of the other issues we ran into on this project is that the schedule was so tight that in order to utilize the funding that was allocated , it required to be no right-of-way because the right-of-way acquisition process would take too long to get through. As result we would needed to boil down the alternatives. That led us to either the expansion, which allowed us to utilize a lot, or the interchange with roundabouts at the end and the diverging diamond. These are the alternatives we took to the public meeting and work with the state to walk through the alternatives. So that is a little bit as to how we’ve got to where we’ve got the diverging diamond.
We started with the expanded diamond interchange. One of the things we ran into this was by the time was the U-turn one truck at this location. We realized the amount of trucks that were required to interchange required us to design this interchange with two trucks side to side. It is unusual in a highway; we don’t see that kind of a need, but in this case because we had truck places on the North side to side. We cannot say trucks can all use one that because it would cost too cause too much. For that type of a turn, you put one truck in the right hand and left turn lane by the time you put that second truck and make better because of the truck overlap, or truck off tracking, then that truck is down pretty far, and what happens then is you have potentially impacting the waiting vehicles heading eastbound. What that did was force us to move this stop are that you can see right year we had to move it back. In order to accommodate this so what ended up having ironically by trying to improve the length of this left turn lane reaction it shorter because we had to position the stop are. Really that was a problem.
As we started to look at the roundabout option, I said we had the need for a dual left maneuvered northbound to westbound. But the original roundabout had the layout of only a single lane. The reason why was because we could not lay out a two two-lane and get it to fit it within the existing road for print without impacting our bridge. Remember, the progress purpose and need could impact that bridge. There was some real concern from the freight industry that we actually went out and worked with the turn of the trucks to do this roundabout. We knew that was going to be a real concern for them.
That led us to the DDI and it is got some real good advantages. One, it allows very nicely turn to interstate trucks in time because of that smooth geometry you have for that ramp. It also provides very good capacity because, for those that know anything about DDAs, what happens is the signal right here is a two-phase signal. The signal right here is corded made it with it so as result this traffic is moving at a pretty good rates. We get a lot of duplicate this interchange, much better than a traditional signal or even the roundabout as we found during our analysis. This was something that the truck community really embraced and they found it was very interesting for how we receptive they were considering first one in the state of Ohio said they were not exactly familiar it.
We talked about turning the two trucks together, we would have to get creative and this was touched on, what we needed was about 4 feet of pavement, or with the pavement from edge of pavement to edge of pavement. We did not have the being separation between the lanes I could see a situation at night, or pavement that is faded where you could get three passenger cars pulling up to the intersection. The problem with that is there are only two receiving lanes on Roberts Road so that’s a problem. With the Lane separation, what we’ve done is we’ve gone through with the striping there that allows the trucks to drive across the pavement now, impacting another big vehicle sitting in the other Lane it also gives a defined route for the passenger car. Here is an example during or while the DDI is in use of a truck that actually is utilizing the pavement. We did that one correctly for them.
For those that have actually we’ve seen this many times, where we don’t provide enough with for a truck to make a turn solely in their lane, I know I would not want to be the car sitting on the driver side of this truck if he’s doing this turning maneuver.
Another thing that the stakeholders really liked about the DDI was the geometry along Roberts Road to the interchange. For those that think the DDI does not work on high-speed facilities, let me show you something cool. On the west side of the interchange we have a high-speed facility. On the east side we have a low low-speed facility. The DDI worked very well for both sides. Basically because what we did is we introduced ORS do see curves through the crossover intersection as a means for slowing them down and I think Jeff Shaw alluded to this earlier in the presentation, about how sometimes you can actually get there flowed through these interchanges even if you store them down a little bit, which is what we saw here.
If we couple that with the wider turn lanes through the crossover, the crossover extends as well as extending the tangents through the intersection, which is shown in yellow. This does make the crossover intersection very intuitive to the drivers. That really is the key. The key to the DDI is right here at this crossover. Again, this is intuitive, not just for trucks, but also for the cars to make this a very effective interchange. The other thing we were able to do with this location is replace the dedicated bicycle lanes across Robert with an interchange. This is one of the first DDIs in the country that can handle more than one mode of transportation. And here is an image showing across the bridge and the inside of the bridge, but remember because as alluded to what foot the traffic but it still took the right of the vehicles which is what you would expect for a bicycle to the.
Here is the primary selling point for a DDI. The safety results are comparing a three-year period before construction and that three-year period after the DDI was open to traffic. You can see 48% reduction in total crashes and more suitability, 70% reduction in injury crashes. That is huge. A lot of this is in part by leaving the congestion is you can see on the right we took the level of service from detail, which made it a lot better. There’s also the reduction in the conflict white weight and type of conflict points that or reducing makes this interchange a very, much safer option.
One of the things that we did throughout this project is we actually had a targeted coordination effort with the various freight generators in the area. We were overwhelmed with support for the full bridge closure, because as they told us repeatedly, that when construction starts of us project there were going to do traffic out of this area anyway, there they are going to send their trucks outside of this region because of the construction, because of the congestion at the time of construction this was an option they wanted to go with. One of the lessons I learned is don’t discount a full closure option without first getting into the stakeholders, because as I was you can saves a ton of money and time on the project.
In this location we are getting innovative with the placement of putting a DDI that accommodated the trucks, and maybe in May the facility will be safer and also provide less congestion, or solve the congestion issue so that trucks are not sitting in traffic, which means more money being made and I went would definitely strongly recommend don’t dismiss the full closure option.
So I think with that I’m going to kick it back over to Nicole.
Nicole Coene
Thank you, Brian. 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.
So let’s get started with Jeff and Gil. For a J-turn: do you look at truck volumes and class? How does this work if you have lots of trucks trying to cross several lanes of traffic to get to the median U-turn?
Gilbert Chlewicki
In general, the rule of thumb is if we have 5000 vehicles per day or less on the side road, then we will have an un-signalized J-turn we will go to a Superstreet. For the J-turn concept, we have the [Indiscernible] are not too high and what we do is we will depending on is the signage of the truck so that you will locate the U-turn further way from the main intersection. That way we can cap for the weaving, to make sure that the truck can get across. That’s so how we accommodate the large truck or large classes of trucks by trying to accommodate that maneuver.
Nicole Coene
Thank you, Gil. Another question, How do you accommodate for over size (height, width or length)?
Gilbert Chlewicki
For that it depends on the intersection design and the U-turn. In some cases it will be a multiple curb and emergency vehicles will need to be able to or through from the minor road. For me, they should be able to make a direct left here, because emergency vehicles should be able to handle that like any other intersection. For the DDI, we have in Idaho where they had an issue with data signal under the bridge and cannot get under the bridge, so what are the disadvantages of the DDI is you cannot go back on the ramp. But with this design in Idaho, is they actually designed it so there will be able to get a police to go out just before the oversized vehicles will have a signal so the overhead truck and get across the other side and the back again. These issues do come up and they are being accommodated for.
Nicole Coene
Thank you. Also, do all of the medians accommodate the distance of a tractor trailer combination so the truck/trailer is not blocking the roadway?
Gilbert Chlewicki
It depends on context but generally no vehicles will to go on the road, you would come into the U-turn lane and you make the maneuver you are not taking out into the roadway. As you may future maneuver itself, some vehicles will take more time to clear the U-turn, so some lanes will be designed with a larger lane to get the larger vehicle out of the roadway quicker, but it would be depending on what kind of vehicle and whether and volumes, and also how much right-of-way they have.
Nicole Coene
Thank you. We will over to Jeff now. These are all design concepts that assume that there is lots of ROW available. How would you handle a denser urban environment?
Jeffrey Shaw
That is a good question, Christine. We are not able to really get into a lot of side-by-side comparisons between the equivalents of a conventional intersection would be for a lot of these innovative designs, but as I alluded to in one of the value benefits to these is footprints are actually smaller than an equivalent conventional design. To achieve the same safety benefits and operational benefits of these innovative designs are actually are veritably smaller. Now that said, if we are talking about a dense urban environment, Gil showed you an example coming out of Utah where they are actually doing a narrow or zero media median with days U-turn design called the through turn. That works by pumping out of the loon a little bit further and having a more generous U-turn design. That’s also being done been done in Tucson and other states looking at that same design to go even in denser urban environments we are seeing the same principles being put into use at urban intersections of many kinds. On the roundabout side for example, in very dense and very constrained urban environment there seem any roundabout which have fully traversable islands of both splitter and central islands becoming more popular because you can gain a lot of the same operational and safety benefits, but in very, very small for prints. It really does depend.
Nicole Coene
Thank you, Jeff. Another question for you from James, what type of public training is offered prior to implementation of any alternative intersection?
Jeffrey Shaw
Okay, James. I mentioned there are quite a number of resources available that Federal Highway has produced. We’ve got brochures, we’ve got case studies. We have informational videos, video case studies, etc. So, we try to create a portfolio of outreach and education materials that any agency, state or local, MPO, whoever, and use in their local public education efforts. We’ve also seen where states and local agencies have used our information and have is the reconstituted them as project specific literature so if for example you want to produce your own video about your own project, you can spice splice in some of the footage from the a Federal Highways video or you can use the photos used to illustrate our brochures to down on the time and cost of producing those materials yourself. Then as far as advice goes, do we tell states when asked our advice to make innovative intersections its own campaign in your community and your state, in your region, because you want to get these principles out to the public. You want to keep drivers trained, you want your pedestrians and bicyclists used to the ideas so make them their own campaign we’ve tried to do a lot of that with our social media efforts and we think that state and local agencies can do that as well.
Nicole Coene
Thanks, Jeff. We will go back to Gil. Any considerations about visibility restrictions on dual turn lanes at signalized intersections?
Gilbert Chlewicki
I think in all cases dual turn lanes would be not un-signalized. I think for adjacent lanes we usually have the yield bar a little bit spaced out to let you can see the other side.
Nicole Coene
Thank you. I have a question for Hermanus -- Are there any thresholds or recommendations that were used to determine that these were “freight” routes and that also impacted the selection of the ultimate intersection design choice?
Hermanus Steyn
Thanks for the question. In 2001 the Oregon transportation act received some funding to evaluate all our bridges on some keywords throughout Oregon and in that time they established a committee that would collaborate with the Oregon Department of Transportation to establish these freight routes across the states. The goal for that freight route is they looked at regional trucking routes physically the rest between states coming from California to Washington, for example. They want to make sure during construction that there are alternative route throughout the state. What are some of the key industrial modes and estimations within the states and also look at what has been issued for trucks. It took collaboration of all these different factors that played into dividing the system throughout the state. When it comes to the ultimate intersection configuration, again it is not that we have a specific us be in a safe this is the type of intersection we do everywhere, but the goal is to really work on the planning phase, make them part of the solution. They have meetings on a monthly basis, so we’ve had some great discussions over the years.
Nicole Coene
Thank you. Gloria would like to know if there are there any special considerations for asset management when designing and maintaining this “freight friendly” intersections?
Hermanus Steyn
Thank you. That’s probably a question more directed to the Oregon Department of Transportation, but typically when we do these types of intersections the pavement design is designed to accommodate for or designed for these trucks, so there is a design that is taken into account. Sometimes local agency roads intersect with the state sometimes they need to establish some intergovernmental agreements but typically that’s also established the pavement design for that facility established up front.
Nicole Coene
Would any of the other speakers want to respond to the question as well?
Brian Toombs
I would, this is Brian. I am probably similar to Hermanus’ stance, ODOT does a very good job of logging and keeping track of their assets to through asset management database and tools, but to his point they are handled similar as far as whatever our design is reset the pavement and image with inventory the condition of that, I don’t know Keith might have more he actually is at ODOT.
Keith Smith
Brian, that covers it really well. We have to do an asset management and keep an inventory of everything.
Nicole Coene
Thank you, gentlemen – Keith, while we have you, Troy asked “Can I assume by the view of that ‘super’ street, that pedestrian travel is not encouraged beyond where they live?”
Keith Smith
Actually in this case, our designer had about 38 hours to put this together when we were going to the public to start showing them just the concept of Superstreet. So, he did not include the pedestrian crossing on the drawing. But it is a major concern out there. We have a heavy bicycle movement out there, there’s a bikeway north of the area. We have a high school North of the area where we have students crossing back and forth but there’s soccer field fields south of the areas we will be accommodating pedestrian traffic and will be use on the type of intersection is called a “Z crossing” and it actually reduces the conflict points between pedestrian and vehicles from 4 conflict points down to eight conflict points so it is actually safer for pedestrians and bicyclists as well.
Brian Toombs
Keith, if I could footnote that answer as well – One of the things that we have found with many of these innovative intersection designs is that the they actually offer more convenient options for pedestrians so just take for example a conventional signalized intersection where a pedestrian might have to wait for their walk phase and in some cases with a considerable amount of time and then wait, wait and find finally get the chance to go. With the innovative intersections when they are signalized because those cycles, round around they tend to be shorter and require fewer phases, you actually get to service all to users of the two section more frequently. As Keith mentioned it might look in this case just that a pedestrian option was omitted from of the drawings, but the actually do offer a lot of possibilities and our advice to agencies is but the pedestrian bicycle concerns on the table from the very beginning and make sure that they are a critical part of living alternative intersection design concept forward. And the same thing as freight, we want to do the right thing by all the users of the intersection.
Nicole Coene
Thank you, gentlemen – another question for Keith. Or more of a comment – Have you looked at having the manufacturers benefiting from these costly intersections provide some of the funding?
Keith Smith
Actually, some of the adjacent property owners we have a group that is promoting a development to go they’ve offered to donate some of the right right-of-way. But as far as donating money towards developing a Public-Private partnership towards doing the interchange projects, we’ve not come to with that yet. We are working using some of our safety funds and that sort of thing to develop the Superstreet option out there.
Nicole Coene
Thank you. Last question, can the super straight normally be installed within the existing right-of-way?
Keith Smith
In this case we are going to have to buy a small right-of-way for the loons but the rest of it will be installed with honor existing right-of-way.
Nicole Coene
Would any of the other presenters want to comment on that?
Okay. We will move onto the questions for Brian now. How was the safety assessed? Did they look at any real crash data or simulation?
Brian Toombs
We used real crash data, Ohio Department of transportation does a great job of inventory and the crashes, working with the state highway Patrol to inventory their crashes so what we actually did when I pulled the past numbers was this Aditi I was constructed in 2012, actually open to traffic it is in September. We pulled the before construction traffic of 2009, 2010 and 11, we omitted 12 completely because a lot of that was during construction as well and also covered a little bit of a learning curve there after September of 2012 when it opened and in the after construction crash data we pulled was from 2013, 2014 and 2015. We felt that would give it more of an accurate assessment of what the safety results were.
Nicole Coene
Thank you, Brian. Another question for you – how long after construction was safety evaluated? They are wondering if the results are skewed because people were simply pain more attention to a new scenario and safety results may decline over time.
Brian Toombs
Yes, I answered that but we thought about that and as a result that is why we waited from September and waited until January to give that time for the learning curve because actually what we were seeing was while people were warning how to drive the DDIs there was actually a few more property damage only accident, people were just ride right to figure it out. We wanted to wipe those off because those were really were not indicative of the configuration so much as people just as was indicated, just looking around and eating used to the new scenario gold this was the first one in Ohio as a reminder.
Nicole Coene
Thank you. We have two questions left, so while we’re going to those if there’s anybody that would like to ask a question over the phone, please press *1 on your telephone keypad to be place in the phone to.
Brian, the DDI on the last visitation make sense but can you please explain how the roundabout alternative impacted the existing bridges?
Brian Toombs
Sure, that’s great question because the graphics that I showed were less engineered. The roundabout that we were showing in that drawing was not sized quickly. In order to make a true tooling are multilingual on about the ICD that we need for that roundabout was pretty large. By the time actually got those two roadways back together with the right geometry is let looking out and speak and whatnot, that’s what happened is we’ve are being forced to have to flare the bridge in order to get the geometry back in. The option we had was pushing it away from the bridge enough and not do that to the bridge but in doing so we then had to take right right-of-way. That was the rebalancing both pieces of that and we could not get either want to work.
Nicole Coene
Thank you, Brian. This is the last question we have in the chat pod, Did the previous DDI safety evaluations look at impact to safety for pedestrians and bicyclists? Does anyone know of DDI Ped focused safety evaluation on existing DDI?
Brian Toombs
Okay, so the good news on that is we have a report that has been funded through Federal Highway Administration. It is a very comprehensive evaluation of the first several DDIs that were built and opened in the United States. We’ve got the first seven or eight sites from New York, Tennessee, Kentucky, Missouri, Utah, I think is in there as well. That report is essentially finished and is in final editing process as we speak. It should be published any moment. As part of that copy and audience of evaluation the researchers actually did very thorough before and after audits of the pedestrian experience at those interchanges. So, they basically applied a combination of road safety audit and accessibility audit is from the standpoint of a pedestrian and compared them before the before to the after and noted both the advantages, disadvantages, opportunities for improvement and so on. That will be an important chapter of that country and save evaluation report and like I said, we are hoping for that to be published any day now.
Nicole Coene
We’ve gotten through all the questions and I don’t see anything else coming in. I think we will go ahead and close out. The recorded version of this event will be available within the next few weeks on the Talking Freight website.
The next seminar will be held on October 19, 2016 and the topic is “Regional Models of Cooperation and Freight Planning.” It is a joint webinar between the Freight Office and the Planning Office focused on regional models of cooperation. Registration is not yet available but I will send a notice out through the Freight Planning LISTSERV announcing when registration is open.
I encourage you to join the Freight Planning LISTSERV if you have not already done so.
Thank you to our presenters and to everyone attending. Please enjoy the rest of your day.
