Talking Michigan Transportation

Why do we need a green light to enter a freeway?

• Season 7 • Episode 226

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After a long hiatus, Michigan is again implementing ramp metering, which helps regulate the flow of traffic from ramps onto busy freeways. It will be used on the I-96 Flex Route portion in western Oakland County.

On this week’s Talking Michigan Transportation podcast, Sarah Gill, operations engineer for the Michigan Department of Transportation’s (MDOT) Metro Region, talks about how it will work and the history of ramp metering in Michigan. 

Gill explains the key reasons for implementing ramp metering, which include improving merging, reducing crashes and reducing travel times. An MDOT how-to video offers guidance on the concept.

Next week’s episode will delve farther into the topic and include conversations with a traffic safety engineer with the Colorado Department of Transportation (CDOT), who will talk about how successful the concept has been in the rapidly growing Denver area. You’ll also hear a national perspective from the director of safety and mobility at the American Association of State Highway and Transportation Officials (AASHTO).

Jeff Cranson:

Hello, welcome to the Talking Michigan Transportation Podcast. I'm Jeff Cranson. After a long hiatus, Michigan is again implementing ramp metering which helps regulate the flow of traffic from ramps onto busy freeways. It will be used on the I-96 flex route portion in western Oakland County and I spoke with Sarah Gill, who's the operations engineer for MDOT's metro region, about how it will improve safety and the flow of traffic. She also knows a lot about the history of ramp metering, going back decades, and why it was abandoned in Michigan.

Jeff Cranson:

Before this new deployment next week you'll hear from a traffic safety engineer from the Colorado Department of Transportation who will talk about how successfully the concept has been there in the rapidly growing Denver area. You'll also get a national perspective from the Director of Safety and Mobility at the American Association of State Highway Transportation Officials, or AASHTO. So stay tuned for that. But first, again, we'll hear from Sarah Gill at MDOT. So, Sarah Gill, first time visit to the podcast. Thank you so much for taking time to be here. I mentioned in the intro what your work is. I always think that to the general public I know traffic safety engineers think in terms of operations, but I think the general public thinks I drive the car, I'm the operator, so how do you, you know, talk about your background and how you get into this and what drives your passion for traffic safety and operations and how you explain to people what that means, because I don't think everybody knows that. You know we have an operations division and why that is.

Sarah Gill:

Hi, Jeff, and thank you for having me on. I've actually been in operations since 1998. Yes, I started when I was 12, so don't do any math behind that. But I started working part-time through college and once you get in operations you either love it or hate it and I never know what I'm going to see each day. And that's the part that I enjoy that I love, really the diversity in what my day brings. In my normal day job I manage the control room operations at Southeast Michigan Transportation Operations Center huge mouthful, so most people know it as SEMTOC and I also manage the safety service patrol in the Detroit area. We do Wayne, Oakland and Macomb, the freeways and all of the state trunk lines in the metro region.

Jeff Cranson:

Talk a little bit about that operations center and what goes on there, because some people have seen stories, some people have had the privilege of touring it, but most people don't even know what that looks like.

Jeff Cranson:

So talk about that, the SEMTOC control room.

Sarah Gill:

We are 24-7 managing roadways. We're co-located with the state police dispatch. They are dispatching troopers for the Metro South and Metro North post out of Taylor and Oak Park and we work because we're in the same room. We share computer systems we share obviously we're communicating back and forth.

Sarah Gill:

But any incidents that are going on along the roadway, the control room is finding them with the cameras, because in Southeast Michigan we have about 400 cameras and we have about 250 of the dynamic message signs.

Sarah Gill:

So once we find it on camera we make sure that the first responders know exactly where it's at. We can get the incidents managed quicker so we can get the police there faster. Make sure that they know their correct location. A lot of times when somebody calls 911, they see a sign that says eight mile, two miles ahead, or they don't remember where they're at. They just remember crossing something. So a lot of times finding it on camera really does streamline incident management. We can pinpoint that location, make sure that the responders get there quickly and safely and they can manage the incident. We get the safety service patrol there to help with traffic control so the police can focus on managing the incident. We'll do the traffic control and the specialists at the TOC itself will message on those dynamic message signs, along with putting the word out on MiDrive and sending a Twitter or X notice out, just making sure that we get the word out what's going on and make sure that people are educated and can make alternate choices if needed.

Jeff Cranson:

And I think that's the best thing that those dynamic message signs can do, and eventually I think we'll all have the technology where this information is going directly into our vehicles. But people want to know if they're delayed, why. It's like you're sitting on the tarmac and nobody's telling you why you haven't taken off yet. Right you just.

Jeff Cranson:

There's a lot of comfort in just knowing what's going on

Sarah Gill:

Knowing what's going on and rotating it with the travel time, to say how bad is this going to affect me is also, uh, makes allows people to make better choices of should they detour. But that's what really drives my passion is you can visibly see how we're improving traffic and mobility in Southeast Michigan If there's a bad crash that's going on between the work that we do with the control room and the safety service patrol, making it a safer scene, making it flow better by providing alternate routes or even modifying the signal timing. We can adjust some of the signal timing. We can work with our county partners and our city partners to really smooth and streamline that signal timing to route traffic differently, and you can see visibly how just the work that we do affects other people's lives and improves that mobility.

Jeff Cranson:

And I've had people ask and I'm sure you have many more times than I have, even if it always takes me 18 minutes from this point to get downtown why do I need to be told it's 18 minutes to downtown? And I answer that's exactly why. Because there's comfort in knowing that my commute is going to be what I expect it to be right and I want to know when it's not.

Sarah Gill:

Exactly.

Jeff Cranson:

Yeah. So, speaking of signals one of the main things I wanted to talk about and before we get into the implementation of ramp metering on the I-96 flex route in western Oakland County you filled me in on some history. I had this vague memory that MDOT had done some ramp metering back in the 80s and 90s, but I didn't know what happened or why they eventually abandoned it. So can you talk about that?

Sarah Gill:

Sure, again, I wasn't working at this time, but I did look up the history on this. But we actually started ramp meters in 1962, where we had a lodge project going on, and in 1962, we installed a couple ramp meters out on some of the entrance ramps. Then in 1982, we did another deployment and between 82 and 88, we ended up deploying, uh, about 50 ramp meters. They were all within the city of Detroit footprint and they were all entrance ramps onto the freeway.

Sarah Gill:

So, like Lodge 75, 94, Davison, all of those had ramp meters on them and we found a lot of good lessons learned with it. We found a lot of what to do and what not to do. There was great logic in that system where it was automated, it would turn on when it was warranted, when the freeway backed up, and we had the ability to turn it off and on manually as well. But we found out a lot of negatives with it. The ramps that we chose had very little storage. They were really short ramps and when you had like three vehicles the whole ramp was filled. So there really wasn't a lot of storage. Those ramps were way too short.

Jeff Cranson:

Then the acceleration was way too short. When you talk about storage, you mean place for the vehicles to actually queue up.

Sarah Gill:

Sit. Yes, yeah, so the vehicles actually just didn't have room. They were backing up out onto the cross streets and then you'd have incidents on the cross streets or you'd have incidents on the cross streets or you'd have incidents on the on-ramps. The on-ramps were just way too short for ramp meters. In general, a lot of the lessons learned that we had were implemented in other states I know you're going to be talking to other states and I know a lot of other states swear by ramp meters and they actually used a lot of the lessons learned that we had to implement their projects and in that time they improved the situation because ours were all analog. When that analog to digital conversion happened, we really lost that ability to use that system. There was no way to upgrade it Even prior to that analog to digital conversion. Just getting parts for it and maintaining the system was a challenge. So between a lot of those lessons learned, the parts and then ultimately, when the analog to digital conversion happened, we really had to stop using those ramp meters at that point.

Jeff Cranson:

So a question might be now that they're being implemented again and the 96 flex route makes a lot of sense because of that additional lane that's operable certain times of the day, peak traffic, just like the flex route on US 23 that some people might be familiar with between Ann Arbor and Brighton why did it take so long? If we learned some lessons and you know you talked about the analog to digital transition, but other states implemented it and seem to be using it successfully I think you'll say that it's all about timing right.

Sarah Gill:

It really is the timing and the need. You've got to have the right geometry for the ramps. You've got to have the right situation for the signals because really it's where there's routine bottlenecks, where there's those normal daily commute bottlenecks, isway, and having those ramp meters to make that emerging more like a zipper opposed to a platoon coming in it really does. Spacing those vehicles out really does help with it. But the reason that we haven't done it is we wanted to learn from the other states. So the other states have been doing it for a while They've got a lot of what to do, what not to do, have been doing it for a while and that's why in our implementation, as you said, we implemented it with the I-96 Flex Route Project.

Sarah Gill:

That's a 12-mile stretch, all the way from 275 to Kent Lake, and we've only chosen eight ramps to put it on because of those lessons learned in other states. We looked at the geometry, we looked at the traffic flow, the number of people that are entering from those ramps, and really modeled it, looked at the data behind it and said, okay, if we had ramp meters here, would it improve the freeway traffic and the flow, and you'll see that there's some ramps that we didn't do ramp meters on and it's either because of that geometry or there's too little traffic entering from it or too much traffic entering from it. Too much traffic entering from it really could also be bad for ramp mannering. So, using all of the lessons learned, all of the modeling that we can do and all the data, we wanted to make sure that we were doing this the correct way and on the correct ramps.

Jeff Cranson:

Did you wonder a few years ago, in the early days of the pandemic, how long it would be and whether we would ever, you know, return to our old habits? And obviously that affects the traffic coming in and out of the city from that part of western Oakland County, because that's really what these commuting patterns are mostly about. Right.

Sarah Gill:

Correct.

Jeff Cranson:

Do you think it has bounced back to a large degree?

Sarah Gill:

To a large degree. Yes, it has, and not even during the pandemic we noticed that the traffic, the people would still drive it, but they would drive less people at faster speeds.

Jeff Cranson:

Definitely faster.

Sarah Gill:

The crashes. The crash numbers were still consistent. They were the exact same. They were probably even more severe during the pandemic just because of those increased speeds. But with respect to daily commute, the working remote versus working in person affected that greatly. But we see, rush hour is back to normal. There are certain days that are lighter than others. Fridays are always significantly lighter than any other day of the week but we do have that normal commute traffic and really setting up the travel times and reliability in your travel.

Sarah Gill:

I know, looking at the data, people used to have to have 45 extra minutes to plan going through this 12-mile stretch. You know a planning time of 45 minutes for 12 miles is really not, that shouldn't be the norm and unfortunately it was just because how inconsistent it was or how those rush hours would just bog down. And now, with that flex route opening up these projects, we plan in five years in advance to align with funding and get things moved around. So just know that we planned this project well before the pandemic and we did all of the full road reconstruct, full drainage reconstruct.

Sarah Gill:

We did a lot in this area and as part of that we did the flex route with the extra lane and we did the ramp meters and the flex lane has really improved that travel time reliability. We went from normal rush hour traffic being like 35 miles an hour to now rush hour traffic is 70 miles an hour on average. There's not really a slowdown anymore. You might be delayed by five minutes at the most. So it's tremendous how that flex route has improved traffic. So now with adding the ramp meters in there and making it so those right lanes don't slow down and we can keep that traffic moving, we're really hoping that it's going to improve that travel time overall and just reduce crashes.

Jeff Cranson:

So it should be intuitive, because most people are so focused on delays and their own personal commute or you know whatever it is trying to get to a soccer game or whatever soccer game or whatever but really the imperative here is safety and talk about why that is that delays cause those kinds of crashes. And I know people get frustrated, they take chances, they do things that they normally wouldn't, so really it's safety that's driving this right.

Sarah Gill:

Ultimately, yes, safety and, you know, towards zero deaths is one of those reasons that we do what we do on a daily basis. We want to do whatever we can to reduce the number of crashes, reduce any injuries and fatalities on the roadway. With ramp meters in general, normally the merging traffic will collide with that right lane traffic and you'll have a lot of side swipes. You'll have a lot of people that are just not merging well and that'll back up down the road and that's where people going from 70 miles an hour to a stopped condition it really does increase those crashes and the severity of crashes. So if we can make these entrance ramps smoother, make it so traffic can enter safer, that way there's no delays in that right lane. You're not going to have those 70 miles to zero type of situations anymore. So with ramp meters, I don't know.

Sarah Gill:

There are a lot of great resources online on the Michigan. gov/ MDOT. If you just search flex route, you'll see a lot of information. There's a brochure, there's some videos. But with regard to these ramps, when you enter them you're going to see a sign that says when flashing, stop ahead. When flashing the ramp meters on, then you'll see a static sign that says form two lanes. If the ramp meters on we want traffic to form two lanes, they're going to stop at the white line and at those signals they're going to alternate green so the left lane will go and then the right lane will go. That way, spacing that traffic out is going to allow for that smoother merge.

Jeff Cranson:

So give people an idea of that cycle. I mean, how long would you actually be sitting still before you get that green light?

Sarah Gill:

It's not going to be long and we have a lot of detection along the ramp itself. If that ramp starts backing up, we're going to make sure that that signal cycles faster as well to ensure that that ramp does not back up onto the surface street. We're going to make sure that the traffic moves well, so you're not going to be delayed long. The cycle length is not like a normal traffic signal. You'll still see the green, yellow red, but it's going to be. The green will blink. For you, that's when the one car goes, and then you'll see that yellow red. You, that's when the one car goes, and then you'll see that yellow-red and you'll just wait for that next green before that next car goes.

Jeff Cranson:

Do you think you'll be taking a look at this to see if it has applications elsewhere? I mean like the congested portions of 94 west of town or I-75, obviously north of the city in Oakland County? Are those candidates for this perhaps?

Sarah Gill:

Yeah, we want to see how successful the ramp meters are and really see how they function. And we do already have an additional ramp meter going in in the University region on that extension of the flex route for US-23 at 96. So there's a ramp meter going in there.

Jeff Cranson:

That's right. We should specify for people. So the flex route now that works well but is kind of frustrating because it comes to an end before you get to I-96, will eventually go all the way to the freeway on 23. And so you're saying that an interchange there will include metering too?

Sarah Gill:

Yeah, correct. So not to speak for Stephanie and Billy, but they have a project. So their flex route normally ends at nine mile and the northbound would always it would still back up, just because between nine mile and 96, you have to get out of that left lane. They're extending that so you'll be able to stay in that flex lane through 96, and it'll actually go right into the ramp to 96 west. That extension of the flex route is also going to add a ramp meter with that and that project should be wrapping up next year, so it'll be active next year.

Jeff Cranson:

Stay with us. We'll have more on the other side of this important message.

MDOT Message:

Even with the best planning, backups and traffic congestion can occur during road construction. This can pose hazardous situations for both motorists and construction workers, particularly when drivers are distracted. Motorists are more likely than workers to be killed or injured in work zone related incidents. Additionally, the leading causes of all work zone related crashes are distracted driving and speeding. So it's crucial to do your part in ensuring the safety of both drivers and focusing on your most important task safe driving.

Jeff Cranson:

Slow down and stay focused driving Slow down and stay focused. So talk real quickly about I mean, this isn't the only tool in the box, obviously Some other innovations, things that you've seen and you know thought had really worked well, that have made a real difference in terms of the traffic flow and operations traffic flow and operations.

Sarah Gill:

There's so much with technology from a connected and autonomous vehicle having the infrastructure being able to talk to the vehicles. There's so much improvement that's happening. The addition to just looking at an incident timeline One thing that we do in all of the coordination with first responders is looking at that incident timeline and seeing what can we do to reduce each different section of it. Incident detection we have a project where we use our normal cameras and it goes through a video analytics and it has actually proven out that we get the location information about two minutes before somebody picks up the phone to call 911 and before 911 can type it into their computer system. So the notification does let us know two minutes in advance and looking at every step of that way, of what we can do on that incident timeline to reduce the timeline along with making it safer in return traffic to normal quicker and hopefully that'll reduce those secondary crashes ultimately.

Jeff Cranson:

Yeah, two minutes is actually a lot secondary crashes.

Sarah Gill:

Ultimately, yeah, two minutes is actually a lot, you know. So, yeah, it is very significant and it's very accurate where? Uh, it's almost a little too accurate because there's times where somebody will pull off to the shoulder to adjust a tie down strap on their vehicle and we'll be notified of that and watch them drive off immediately, you know immediately, but so it didn't really cause much of an issue but, yeah, it's a great system.

Sarah Gill:

There's so many other things from technology with wrong way driving detection, because those wrong way drivers are going in the opposite direction it's a higher rate of fatalities. So there's a lot of different things that technology is doing to hopefully make those roadways safer and alert the motorists that something's going on ahead of them.

Jeff Cranson:

Yeah, I think one of the biggest things there and I think it's a really good thing that we've been piloting some of that technology to prevent wrong-way driving on the west side of the state, and that'll pay dividends everywhere, and some other states are doing similar things. But if NHTSA could succeed in what they set into legislation a few years ago and require some kind of detection to see if anybody's been drinking before they get in the car, that would make a huge difference, because the vast majority of those wrong-way crashes, as you know, involve some kind of substance abuse.

Sarah Gill:

That's definitely another topic too. But with regard to people need to be responsible behind the wheels and they need to make sure that they know and understand the laws, make sure that they are responsible drivers. I know the move over law is not taught well where people think it's move over or slow down. That's how it started out, but we changed the law to be move over and slow down, so you see a first responder on that side of the road. You've got to move over if you're in that lane next to them and all lanes have to slow down 10 miles an hour under that speed limit. And then, as you're driving, you've got to be responsible not watching YouTube on your phone and not driving under the influence of anything under the influence of anything and the police have to be able to enforce these laws and then the court system have to uphold it. So it's really a bigger issue ultimately is we need to make sure that we hold everybody accountable to really doing the right thing.

Jeff Cranson:

Yeah, we could definitely do a whole other episode on that. I think what I've found is so difficult in talking about this over the years is that people like you traffic safety engineers, designers, everybody are doing everything they can to human-proof the system, Because, no matter what we say about driver responsibility and driver behavior, we know humans are going to do human things and we've got a plan for that, right, you've got a plan for that.

Sarah Gill:

But, honestly, you also need humans to do human things. You want people to make good choices behind the wheel and compassionate choices behind the wheel. If you have to choose between hitting a person or a thing, it's easy to choose not hitting the person.

Jeff Cranson:

Now you're talking about the trolley car experiment and that's a whole other topic. But yes, that's the ethical dilemma. Yes, so, Sarah, thank you. Thank you for taking time to talk about this. I really hope this goes well and I'm really glad that when you say that people either love or hate operations, that you love it. We all benefit because of people like you, so thank you for doing what you do.

Sarah Gill:

Oh, you're welcome and remember, if you do drive on one of these eight ramps, it's a couple week process for us to turn all of them on because we do have to go through individually and test things out on them. We've perfected the computer system portion of it, but it'll be a couple weeks before we get all eight ramps working. If you see the flashing yellow, just proceed, enter the freeway like normal and it's like a normal yellow light. There really isn't a learning curve in this. If you see a green light, you go. If you see a red light, you stop. So the blinking yellow, you just proceed and enter the freeway like normal. And if anybody asks you, why are we doing ramp meters, the three reasons that we do ramp meters is to improve merging, reduce crashes and reduce travel times.

Jeff Cranson:

Yeah, and I'm glad you put crashes ahead of travel times. But yeah, you're right, I mean it's a good reminder about the red light and green light, just like youth soccer, right, they say everything we need to know we learn in kindergarten and that includes red light, green light exactly thanks, Sarah all right, thank you, Jeff I'd like to thank you once more for tuning in to talking Michigan Transportation.

Jeff Cranson:

You can find show notes and more on apple podcasts or buzzsprout. I also want to acknowledge the talented people who help make this a reality each week, starting with Randy Debler, who skillfully edits the audio, Jesse Ball, who proofs the content, Courtney Bates, who posts the podcast to various platforms, and Jacke Salinas, who transcribes the audio to make it accessible to all.