• Episode 41 – Mast Arms, Span Wire and other Traffic Signal Structures
• Episode 42 – A multi part episode where I interview Steve Williams of Georgia Road Geek
• Episode 43 – Roadway Safety Assessments
• Episode 44 – In Pavement Lighting and other “Conspicuous” items of note, a grab bag episode

So stay tuned!

• Effectiveness of “Children at Play” Warning Signs
• Theme Music: Five Star Fall, Mercurial Girl, Magnatune.com

No Transcript this week

• Theme Music: Five Star Fall, Mercurial Girl, Magnatune.com

Hello and welcome to another edition of Talking Traffic. My name is Bill Ruhsam and I host this podcast and its sister website, talking traffic dot org. Today is Monday, June 27, 2011. This is episode 39 of Talking traffic.

Today’s topic is about trucks. All kinds of trucks. But before I dive into the nebulous term that is “trucks” let me throw some engineer-speak at you.

When we are designing or analyzing roads, we talk about the “Design Vehicle”. The design vehicle is the largest type of vehicle that is most likely to use that road. For example, if I’m working on a residential subdivision, I dont’ need to design the road to allow a tractor-trailer to turn around in a cul-de-sac. No, a typical large vehilce for a subdivision would be a UPS or FedEx truck. Now, the occasional tractor trailer might come into that roadway, maybe a moving truck, but it only happens occasionally, and the inconvenience caused by having to back up a tractor-trailer to turn it around is small compared to the inconvenience of designing the subdivision to allow the truck to drive around as if it were an interstate.

It’s important to determine at teh very beginning what your design vehicle is because it will affect many different things in your roadway project.

Now, let’s talk about trucks. When I, as a traffic engineer say “truck”, I mean some specific types of vehicles. I’m not talking about pickups or SUVs or dooleys or anything that you migt see in a Ford commercial. I’m talking about larger vehicles that are intended to carry freight. These trucks break down into two cateogries. Single Unit trucks, and Multi Unit trucks.

Single Unit trucks are trucks that don’t articulate, that have a single frame to which the wheels are attached. UPS and FedEx trucks are good examples of these. dump trucks and garbage trucks and smaller moving trucks are all examples of the single unit truck.

Multi-unit trucks include the typical tractor-trailer combination that you see everywhere. These come in various sizes measured from the center of the front axle to the center of the rear most axle. So, when I’m throwing engineering speak at people. I would refer to the WB-62 design vehicle, which means a multi-unit tractor-trailer combination that has a 62 foot wheel base. This truck is actually about 69 feet from nose to tail. There are also the WB-40 and the WB-50 and the WB-65. For trivia purposes, the WB-65, which is 74 feet from nose to tail, is the vehicle used when designing interstaets and interstate ramp terminals.

The importance of the design vehicle becomes clear when you start putting together the design of intersections and sharp curves. Larger trucks need more room in order to make turns. The rear wheels of a truck–well, of any vehicle, really–will run to the inside of the front wheels. This wider path made during a turn is called overtracking, and its why you see large trucks swing out really wide when they’re making right angle turns at intersections. The distance and width needed to ensure that the rear wheels of the design vehicle stay off the edge of pavement, or out of the adjacent lanes, can add a lot of cost to a design project.

Next time you’re walking in an area that has curbs and you come to an intersection, look at the corners. Do you see tire tracks up against the curb faces? Do you see tire tracks on top of the curb, or on the sidewalk? Are the corners, maybe including the pedestrian ramps, broken and cracked? If any of these are true, it means most likely that truck drivers are running their rear wheels up and over the curbs when they’re trying to make turns. This could be becuase the driver isn’t very good, but more likely it’s because there’s not enough room for the trucks to clear when taking their overtracking into account.

Large vehicles are also important to consider when we’re designing intersections and considering the time it takes to accelerate. For example, the distance you need to be able to see to your left, or to your right, when you’re trying to turn onto a roadway. On a 45 mile per hour road, with no other consideations, that distance should be 500 feet if you’re driving a car. If you’re driving a tractor trailer, then I have to add another 270 feet! A football field worth of view, basically. That means no hills, curves or bushes to block the view of that truck driver trying to make a left turn.

Similarly, if I’m working on signal timing, and I know that large trucks are going to make a significant percentage of my traffic stream, then I have to include the additional time it’s going to take to move each truck through the intersection. I can’t just make an assumption based on cars or I’ll end up with a huge congested mess and people calling me and asking what the hell I was thinking.

Then of course, trucks impact how we design pavement! Trucks make a much larger impact on the asphalt and concrete than a typical car for one simple reason: they’re much heavier. So pavements have to be designed to handle the types and quantitiels of trucks that are expected.

Lastly, at least for this podcast, is noise and air pollution. Trucks make up a big part of the noise and air pollution that we transportation engineers have to take into account nowadays. It is possible that when designing a new roadway, the additional noise may be so great that we have to install soundwalls in order to avoid impacting the surroundings. Trucks add a lot to that noise level, so again, it’s important to know what type of vehilce is being designed for.

And that’s it about trucks. There is more that I could discuss, getting into the juicy engineering details, but that covers all the basics.

Thanks for listening to talking traffic. If you like what you heard, or didn’t, be sure to let me know by leaving a comment on the show notes or sending an email to bill at talking traffic.org.

The music you’ve been listening to is by five star fall and can be found at magnatune .com. This episode is released under a creative commons attribution share alike 3.0 license. Feel free to distribute and/or modify this podcast, but please link back to me and to talkingtraffic.org.

Until next time, have a great week.

• Theme Music: Five Star Fall, Mercurial Girl, Magnatune.com

Hello and welcome to another edition of Talking Traffic. My name is Bill Ruhsam and I host this podcast and its sister website, talking traffic dot org. Today is Monday, June 13, 2011. This is episode 38 of Talking traffic and today I’ll be talking about those washboards of the road, Rumble Strips. Sometimes known as shoulder texturing, noise strips, rumble bars, or “Driving by Braile”. I’ll talk about what a rumble strip is and what it is for, plus their implications for safe driving

You will typically find a rumble strip along the edge of a high-speed roadway. These strips are designed to alert you when your tires roll over them by making a strong a vibration and noise. This tells you to that you are leaving your lane, on the way to a meeting with a tree, or possibly another car in a head-on wreck.

Rumble strips can be found on both your right side, on the edge of the road if you drive in the US, and on the left side, on the centerline. That second kind, on the left, is usually called a Centerline Rumble Strip, to distinguish it from Edgeline Rumble Strips.

These types of rumble strips are also referred to by pedantic engineers such as myself as Longitudinal rumble strips. In other words they are placed on the pavement *along* the roadway, rather than across it. You may also be familiar with rumble strips that *cross* the roadway. These are called transverse rumble strips and are used to alert you that you are approaching some sort of unusual location. Typically, I’ve seen them placed in rural areas before intersections that have had a high number of run-through-the-stop sign collisions. The rumble strip is to “wake you up” or just to alert your hazed and road-numbed brain that you need to stop.

Rumble strips are constructed in several different ways, depending on when they placed on the road. If they’re built when the pavement is built, then they can be cut, rolled, or pressed into the pavement as a part of the pavement laying process. On existing asphalt roads, they can be cut into the pavement. You can also use raised pavement markers or striping to make a rumble strip, although those are not as durable as ones that are built or cut into the pavement.

Do rumble strips work? Yes they do! Of course, you have to define what “work” means in order to make that statement.

Rumble strips are effective at preventing run off the road collisions if you drift to the right or head-on collisions if you drift to the left. However, they are dependent on having an adequate room to recover once that rumbling vibratory sound starts you back to awareness. If you are running off the road and immediately after you hit the rumble strip you’re on a soft shoulder or heading down an embankment into the weeds, that is not helpful. A wide safe shoulder is necessary to allow you time to correct and get back onto the roadway.

One dilemma that arises with rumble strips, however, is the concept of “migration”. “Migration” is the concept that rumble strips don’t stop the crash that would have been caused by an impaired or inattentive driver, rather it merely *migrates* it down the road to a point where the driver might cause a different sort of crash that could involve other vehicles. So instead of preventing the single-vehicle rollover or tree-strike, the rumble strip might cause a multi-vehicle collision of some other nature. There have been some studies that *suggest* this occurs, but to my knowledge there aren’t any that have concluded that it *does* to any degree of scientific certainty. It’s a difficult problem to address. How can you tell if that drunk driver who hit the family of five would have instead run off the road five miles back if the rumble striop hadn’t prevented it? the only way to really know is through statistical means, but the noise in the accident database is high enough that it would be difficult to detect a signal that small.

Lets see. What else is there about rumble strips! Oh, back in Texas, I had proposed that we put transverse rumble strips that played a song. Something like the William Tell Overture. I’m sure I wasn’t the first person to think of this and guess what! The Japanese have done it! They cut transverse strips into concrete on several roads to produce music.

Lastly, let’s talk about bikes. There’s all sorts of controversy about bikes and rumble strips. There is, in my opinion, a disconnect between the engineering community and the biking community on what makes a “bike friendly rumble strip”. The current design is to put a rumble strip just outside the striped edgeline of a roadway with a bike-friendly shoulder. A bike friendly shoulder is one that is wide enough for a cyclist to use it as their own roadway. The rumble strip is dashed so that there are gaps between the rumbles where a cyclist can move on and off the shoulder without running into the rumble strip itself. So far so good.

The problem lies in a fundamental problem with having “bicycle friendly shoulders” in the first place: debris. Rocks and sticks and trash and junk and tire-cutting metal tend to accumulate on the sides of roads. This detritus will only be removed by a cleaning operation of some sort, or by the wind-passage of vehicles. That’s why you don’t tend to see a lot of trash in the travel lanes of roads, but you *will* on the shoulders. These shoulders, of course, where cyclists are supposed to ride. A cyclist who is using the shoulder will stick closer to the travel lane than the grass because that is where less debris is. However, the rumble strips force the cyclist closer to the grass and more into the accumulated debris. That causes the cyclist to abandon the whole “bicycle friendly shoulder” concept and ride in the lane.

So that’s an issue. A solution for the *cyclist* would be to put the rumble strip farther out in the shoulder, but that isn’t a solution for the automobile. It’s a problem that doesn’t have a “right” solution. I can talk more about bike advocacy later.

So what did we learn? Rumble strips help you not leave your lane, and they work! Good job, rumble strips.

Thanks for listening to Talking Traffic. If you have any comments on this episode, or the podcast in general, feel free to post them at the website or send an email to bill at talking traffic.org.

The thememusic you hear is by five star fall and can be found at magnatune.com. This episode is released under a creative commons attribution non-commercial share alike license. Feel free to share and change it, but send me some love via a link and a shout out and don’t sell it.

Until next week, have a great week.

When you’re working on a highway design project, you receive information from multiple sources, throughout the life of the project. It’s important to verify the information you receive so that you are not subject to GIGO¹. An example of this is the survey data that you get before you can start any of your design work. The survey crews will go out and locate where the roadway is, the edges of pavement, the location of each utility pole and fence and bush and drainage pipe. All the above-ground features will be found and located to (hopefully) a very tight tolerance. It is usual to take the survey data, put it on the plan sheets, and then walk the project to confirm that A) everything on the survey is located correctly and B) everything in the field is on the survey. Typical problems that arise and have to be corrected are drainage pipes that aren’t found or manholes that aren’t marked. That is one example of field verifying information.

Another is utility information. Utilities include water lines and gas lines and electrical power cables etc. These are fairly easy when they’re strung on overhead utility poles: while I might not know who’s lines are strung on the poles precisely² I at least can see them, and I know where the poles are. I will know if I have to move one of those poles and that some Generic Utility Company will have to come out and restring their lines.

It gets more complicated with underground utilities. Sure, there are manholes that can be found that identify point-to-point where some things are, but generally we’re dependent on Utility Companies to tell us where the various water lines and gas lines and underground power lines are. There are methods³ for verifying the information received from the Utility Companies but it’s much more difficult.

However, there are times when it’s easy. For example, if a utility crosses a bridge, it has to do so by hanging from the deck or a beam. These are easily found and verified by walking under the bridge and looking up.

Just yesterday I discovered that some utilities that we’d been working on feverishly did not actually exist.

They may be somewhere, but they’re definitely not where we thought they were, i.e. they’re not hanging off the bridge we are working on. This makes life much easier, but it also means we did a lot of work for nothing.

So, once again, always verify your information in the field, to the extent possible. I hate learning lessons I already know.

1. Computer Science term: Garbage In, Garbage Out
2. could be power, or cable tv, or telephone, or fiber optic
3. in Georgia this is called Subsurface Utility Engineering and has four different “levels” of quality. Qual D is just a records search. Qual C is a site survey as I’ve described above. Qual B is when an underground utility is located via a magnetic cable finder or other method and then the location of that pipe or cable is surveyed on the surface. This is what you see when you see yellow or red or blue paint on the ground marking utilities. Qual A, the best level, is when a hole is vacuumed in the ground and the actual cable, pipe or whatever is physically surveyed for exact X, Y, Z coordinates

I happened across this particular situation in an alley.

I noticed the eroded watercourse as I walked over it and looked to see where it was coming from. I followed the water back to the hole in the concrete wall shown on the top left of the image. You can see a closeup of the hole in the following image.

You’ll notice that this hole was not created at the time the wall was constructed. You can see rebar within the hole and it’s a rough-hewn rectangle. It’s obvious that someone came along and knocked it out to allow for water to leave the parking lot and drain away. There has been significant erosion underneath the hole. You can see a line on the wall where the level of ground used to be. This has all been caused by the drainage from the parking lot.

Here’s a picture of the parking lot.

You can see, in the center of this image where some debris is against the wall, the low point in the parking lot where the hole was knocked out of the wall to allow water to escape. It’s hard to tell elevations from this picture but when I was standing there, it was obvious that without some sort of drain inlet, the parking lot would develop a very deep pond until the water could seep through the cracks in the asphalt.

This image shows where the water eventually ends up going. It drains across the alley and into a drop inlet where I assume it meanders its way through the Atlanta stormwater system to the Chattahoochee.²

Questions that immediately jumped to mind when I saw this were:

• What are the legalities of the owner of the parking lot arbitrarily knocking a hole into the wall (which is owned and maintained, I’m sure, by the parking lot)? Should a permit have been obtained? Is there anything actually unlawful about this situation?
• Who owns the swath of land between that wall and the alley? If it’s the owner of the lot, then I don’t think there’s anything going on here that is wrong, per se, although the condition of the eroded drainage course isn’t something that qualifies as “good”.
• What are the permit responsibilities for property owners within the City of Atlanta for maintaining the drainage of their properties? Is the property owner responsible for the damage that the water is causing to the alley or is that the city’s responsibility?

Now, if I were the City, I’d want to make it the property owner’s responsibility to address the problems I see in these images. There’s obviously too much water coming through that drainage hole to be handled by a grass or dirt drainage course. The erosion demonstrates that. There should be a properly piped outlet or paved ditch that takes the water to the stormwater drainage³. Unfortunately for the property owner, I can tell that there would have to be some significant pipe installation to address the drainage here. You couldn’t just pave a ditch from the hole to the drop inlet because that would cross the alley, impeding traffic. The most proper way would be to take the water into a pipe, which is installed underground and connected to the box the drop inlet is attached to.

If I were the property owner, I’d want the city to handle and maintain the drainage because that’s an expensive proposition. From my own experience⁴ I’d say that if this became an issue, the property owner would be stuck with the cost of addressing this problem. I think there are plenty of city ordinances and regulations that would place the onus on the property owner.

But would such a condition arise unless someone made an issue? Probably not. I mean, the only reason I happened to be talking about this is because I was walking down the alley and noticed it. The drop inlet to which the water was draining seemed to be functioning fairly well (although a lot of that sand-colored stone you see in the image was piled up on leaves and other debris, blocking half the grate). So long as the amount of water being handled by the inlet exceeds the amount coming off the parking lot and alley, no problems will occur to the other property owners adjacent to this drainage feature, notably the apartments and houses on the left side of the image.

I took a close look at that drop inlet to see if it had been overwhelmed during our last rain incident and it seemed like no problems had occurred. However, the inlet is in a slight declivity, which is the low point of the alley, but not the low point of the entire area. There is a small berm, shown against the rock wall in the mid-bottom-left of the image above. The other side of that berm is the back yard of a private residence which slopes toward the house, and not toward the alley. If enough water comes to that drop inlet to overwhelm its capacity (and that’s easy to do if it has a clogged grate) then the majority of that water could spill over the berm and into that yard.

The clever or close-reading among you will immediately object to the inference I’m drawing here: “But the amount of water going to that drop inlet is independent of whether that parking lot has a properly designed outlet!”

This is true. However, let’s postulate the following: The homeowner was flooded because the drop inlet couldn’t handle the rainfall because it was blocked. Who’s fault is that? The city’s because it didn’t properly maintain the inlet or the adjacent parking lot for causing a condition that drove significant amounts of material into the inlet?

That, of course, would be something for the courts to decide.

It may be that these questions have already been answered. I’m not experienced with City permitting and drainage/erosion/stormwater issues. That’s more of site engineer’s bailiwick than an transportation engineer’s. These are the kinds of things I think about as I move around our built areas⁵.

1. Momocon is an Anime convention and what I know about Anime can be fit onto a 3×5 index card
2. You can also see an attractive woman who is suffering from a charisma modifier of -5 because she’s smoking. Why do people smoke anymore? I don’t get it! It’s expensive, a lot of people like me find it a huge turn off, and it’s being aggressively shoved out the door and into the street. Oh, and it will kill you
3. This feature is what we call the difference between sheet flow and concentrated flow. Sheet flow is what you get from water draining over ground without being concentrated by natural or built features. Think a hillside or a smooth parking lot. Concentrated flow is just that, where water is channeled into a course, such as a ditch or a pipe and becomes concentrated. Concentrated flow can be very destructive if not properly handled
4. very limited. I haven’t handled much in the way of local jurisdictional permitting and nothing to do with site plans and drainage
5. Yes, I’m a geek

• Episode 26 – Transportation funding in the United States.
• Georgia House Bill 277
• Theme Music: Five Star Fall, Mercurial Girl, Magnatune.com

Hello and welcome to another edition of Talking Traffic. My name is Bill Ruhsam and I host this podcast and its sister website, talking traffic dot org. Today is Monday, March 7, 2011. This is episode 37 of Talking traffic and today I’ll be talking about transportation funding. Specifically, transportation funding in Georgia.

Firstly, a warning and a reference. This episode is `about a bill that was signed into law last year here in the great state of Georgia USA. It’s complex, and convoluted and an example of why politics is so messy. If you’re interested in hard, fast, take-it-to-the-road facts about transportation, this is not your episode. Go. Run.

However, if you’re interested in what three years and a lot of political wrangling can produce and how it looks when the light of day shines on it, keep on! This is the episode for you. I encourage my Georgia listeners to stay the course because you will all be voting for or against this funding package on August 15th, 2012. Yes, 2012. We’ll cover that in a moment.

And, I mentioned that I’d give you a reference. Well, I’m referencing you back to Episode 26 of this very podcast: Transportation funding in the United States. That episode talks about the basics of how Americans fund their roads. *This* episode is getting into the specifics of how Georgians *may* decide to supplement their funding revenues. On with the show…

The first thing I’m going to do is summarize what House Bill 277 of 2010 enables for Georgia. Then I’ll discuss its specifics in general form. Lastly I’ll discuss its specifics. Seriously, it’s that complicated.

In short, House Bill 277, also called the Transportation Investment Act of 2010, enables voter referenda on a 1% sales tax for transportation funding. This sales tax would apply regionally, rather than statewide.  That’s the easy part. I just gave you the “in short”. Here’s the “in medium”.

This bill sets up what’s called a “regional roundtable” that will select from a set of projects that will be implemented with the funding acquired by the sales tax. There will be twelve roundtables, one for each region. These roundtables will comprise elected officials from the cities and counties and would have the discretion to select and approve the project list.  Once the project list is approved by the roundtables, it goes before the voters, again on August 15, 2012, who will vote the 1% sales tax up or down.

That was medium. The devil is in the details, however, and this law has a lot of details. If you want to stop now, I don’t blame you, because we’re about to go running down the rabbit hole.

Here are the details. From the signing of this bill by the Governor to the August 2012 vote, there are a lot of things that must be done. Some of which are already completed. After all, this bill was signed into law a year ago in 2010.

Step One: Step one is actually step zero because it wasn’t enacted by the new law, it’s something that has been in place. Step one is for the Planning Director of the state of Georgia to submit the Statewide Strategic Transportation Plan, which has to be approved by the Governor and the State Transportation Board.

Step two: The Planning Director submits a list of recommended criteria for selection of projects. The types of criteria that the director can recommend are spelled out by statute, but there is lots of wiggle room for specifics. The recommended criteria are sent to local planning organizations and governments within the twelve special districts or regions. The organizations and governments have a set amount of time to comment on the recommended criteria.

Step three: The regional roundtables are assembled. These roundtables comprise two representatives from each county within the region. The representatives are the County Commissioner and a Mayor who is elected from amongst all the mayors of the county.

So, on to Step 4: each regional roundtable selects from within its membership 5 members who will be the Executive Committee. And just to make it even more fun… well let me quote from the law:

The executive committee shall also include two members of the House of Representatives selected by the chairperson of the House Transportation Committee and one member of the Senate selected by the chairperson of the Senate Transportation Committee. Each member of the General Assembly appointed to the executive committee shall be a nonvoting member of the executive committee and shall represent a district which lies wholly or partially within the region represented by the executive committee. The executive committee shall not have more than one representative from any one county, but any member of the General Assembly serving on the executive committee shall not count as a representative of his or her county.

Fun, don’t you think?

This might not sound too complicated, but remember that there are twelve regions defined in this law. And Georgia has 159 counties. If you do the math, that means that each roundtable will consist of 26.5 members, on average. 26 politicians. And there’s the 3 non voting members of the executive council, for 29 total politicians.

Step 5 is for each regional roundtable to review and amend or approve the set of criteria that were produced during step 2.

Step 6 enables local governments, which means everyone besides the State of Georgia, to propose projects for inclusion in the list of things to be paid for by the new sales tax. This list doesn’t have to be fiscally constrained. In other words, this list is the whole kit and caboodle; the wish list for everything everybody wants done. The planning director takes these suggestions and compiles a comprehensive list of potential projects for each of the twelve regions.

Step 7. Wow there’s a lot of steps. Keep in mind that these numbered steps are my own breakdown. This is not specified in the law. Step 7 is for the executive committee to select from the potential project list those that fit within the projections for income over the ten years that this 1% sales tax will take place. Yes, ten years. After the executive committee has approved the list, the roundtable will “consider it”. That’s what it says in the law. I’m not sure what that means.

Anyway, step 7 continues with public meetings that present the proposed project list to the public and everyone has the opportunity to comment on it. After all the public comments and any revisions, the roundtable as a whole has to vote the list up, or down. If they do not approve the list, then amendments and revisions can be negotiated that take into account the criteria established back up in step two.  Then they can vote again. Their deadline for approval is October 15, 2011. I’ll cover what happens if they don’t approve it in a moment.

All right. Are you bored or confused yet? I’d be confused too, if I didn’t have a crib sheet in front of me. So far we’ve established 12 regional roundtables and those roundtables have approved a list of projects by October 15, 2011.

Now we move on to step 8. Statewide referenda! On August 15, 2012 (unless they move the date between now and then) the voters in each region will be called on to vote yea or nay on the sales tax. The tax will go specifically to funding that list of approved projects, plus some other stuff, which I’ll discuss in a second. If approved, the tax will begin to be collected the following January and will continue for 10 years, or until the revenues have succeeded in financing the entire project list, whichever comes first.

But let’s talk about sticks and carrots. I’ve assumed during this discussion that everything would be approved by the roundtables and the voters. What if it isn’t? There are some significant sticks built into the law which come into play at various times, and there are some carrots, too. Sticks first:

In order to talk about the sticks I need to remind you that most transportation projects are paid for partially or wholly with state or federal funds. A typical split is 80% state or federal and 20% local. If the roundtable doesn’t approve a list of projects by October 15, 2011, then the region is declared to be in “special district gridlock”. Yes, that’s written into the law. If this occurs, then two things happen. The first is that the local match goes to 50% and the second is a requirement that 2 years pass before the roundtable can try again to reach a consensus. That’s 2 years with a 50% local funding match for every local government within the region. Stick number one.

Stick number two occurs at the general referendum. If the voters do not approve the list of projects and the sale tax, then the local match climbs to 30% and stays there for at least 2 years. The law reads, “for at least 2 years and until such time as a special district sales tax is approved”. So even if the very next month there is a special election that approves the tax, the local governments in that region will still be stuck with the 30% match for 2 years.

Those are the sticks. The carrots involve the local match, but also the “other stuff” I mentioned before. If the voters approve the sales tax, the local match drops to 10% for the entire period of the sales tax. That’s a boon for local governments, assuming that the state has the other 90% to throw into the pot. The “other stuff” involves how the sales tax is split during the ten years it’s being levied.

The tax will be collected regionally, and 75% of the tax will go to funding the project list that was approved by the voters. The other 25% will be distributed back to the local governments based upon a formula that the state department of transportation has been using for years. That 25% can be used by local governments for transportation projects of their own designation, in any manner they choose. It can be used for 100% locally funding projects or it could be used as the 10% local match to get additional state funding. So the local governments have incentive beyond the project list for seeing that the voters approve the tax.

That was the long version of the Bill. If you want to know the fully-fleshed out version, I encourage you to read the bill for yourself, which I’ve linked to in the show notes. Believe it or not, I *still* glossed over some details in that description.

So we have a transportation bill that imposes a 1% sales tax, to be collected and distributed regionally. The regions determine their own list of projects, based on a master list provided by the state planning director. The regions have powerful incentives to both approve their lists and to vote yes on the tax. The tax will be in place for ten years.  That’s about the shape of things.

Can you smell the scent of politics? This is just ripe with it! Getting this tax past the voters at the end of a recession is going to be a challenge to say the least.

For the record, I am in favor of this levy. Why? Well, from a personal standpoint, this tax would pay for projects which pay for my livelihood. From a more regional standpoint, this is the only tool we have right now to pay for necessary infrastructure maintenance and improvements. The well is dry, people, and the gas tax that is currently in place is worth less every year. No legislator is going to propose a fuel-tax increase this year, so our options are limited.  Additionally, from a regional standpoint, the more rural counties and cities should be in favor of this levy. Their share of the 25% is as much or more than they’d get from their own 1% sales tax, if they enacted one.

But this isn’t about Georgia politics. This is about how complicated transportation funding can be when the realities of life and politics are forced up against the realities of needing additional monies. Everyone acknowledges that there is a significant funding gap, nationwide, for transportation infrastructure. The hard part is doing something about it. My description of Georgia’s law is illustrative of what is going on across the country. You may not be aware, but one of the agenda items for this year in Washington is to take up the next transportation funding act. The last one, SAFETEA-LU, expired last year and has been extended to enable the highway trust fund to keep operating. There may be some big changes coming out of the next one.

I’m in favor of transportation infrastructure funding not just because it pays my bills but because it’s what makes a vibrant, strong economy. Like it or not, the stuff we produce and consume has to move around. Those highways aren’t just ways for you to get to Boca quickly. They’re the lifeblood of our economy. On a local basis, the funding applies to transit and to bike lanes, to streetscape improvements and sidewalks that make our towns more livable. Please remember this if it comes your turn to vote for a transportation funding measure.

Thanks for listening to talking traffic. If you have strong opinions about what you just heard, feel free to send an email to bill at talkingtraffic.org or leave a comment on the show notes. I encourage vigorous debate.

The music you’ve been listening to is by five star fall and can be found at magnatune .com. This episode is released under a creative commons attribution share alike 3.0 license. Feel free to distribute and/or modify this podcast, but please link back to me and to talkingtraffic.org.

Until next time, have a great week.

• Theme Music: Five Star Fall, Mercurial Girl, Magnatune.com
• Safety Effectiveness of the HAWK Pedestrian Crossing Treatment

Example of a HAWK Beacon
(source: FHWA.dot.gov)

Episode 36 – HAWK Pedestrian Beacons

Hello and welcome to another edition of Talking Traffic. My name is Bill Ruhsam and I run this podcast and it’s sister website, Talking Traffic .org. Today is Sunday, February 13th, 2011.

The topic of today’s episode is the HAWK Pedestrian beacon, but let me first give you a teaser on something coming up. It’s also a warning, if you choose to just skip the next episode.

I talk about transportation funding a lot, and the politics involved in it. Last year, the Georgia Legislature passed a bill that is almost the poster child of the saying, “Politics and sausage: two things that you don’t wan tot watch being made”. My next episode will be about that bill in particular, and how it illustrates the compromises that go into providing for transportation funding.

But now, on with the show. HAWK Signals.

The HAWK signal is a pedestrian activated crosswalk signal. HAWK stands for High-intensity Activated crossWalK beacon. Yes, it’s a bit of an acronymical stretch.

The HAWK is also called, officially, the Pedestrian Hybrid Beacon, but I have *never* heard anyone actually say that.

The HAWK is used for a very specific purpose. It is to allow a signalized pedestrian crossing at a location where a traffic signal is not warranted, or where one or more warrants have been met but the decision was made not to install a traffic signal. At those spots, a HAWK signal can increase driver awareness of a pedestrian crossing, thus making it safer to walk across the road.

What is a HAWK? It’s quite simple, actually. So simple that I can describe it over a podcast. A hawk is a cluster of three signal faces in a triangular formation, one yellow and two red. It’s like you dissected a standard red-yellow-green traffic signal and rearranged it so that there were two reds side by side on top and a yellow hanging beneath them on the bottom. I’ll post a picture on the show notes. So, we have this two over, one under — red on top/yellow on the bottom signal cluster. It hangs over the road, typically on a steel pole projecting out over the travel lanes. A crosswalk is painted on the road beneath the HAWK beacon.

During times when there are no pedestrians, the signal remains dark; no red or yellow lights are on or flashing. When a pedestrian walks up and pushes the button, the signal starts flashing the yellow light, alerting drivers that there is something going on. Then the flashing yellow turns into a solid yellow, which then turns into a solid red on both the red lights. At this time, the pedestrian WALK signal turns on, telling the pedestrian that it is safe to cross the street.

When it’s time for the pedestrian clearance interval, the Pedestrian signals starts flashing with the DON”T WALK signal, just like a normal crosswalk, and the HAWK starts doing an Alternating red flash, going back and forth between the two red lights. When the clearance interval is over, the pedestrian signal goes to a solid DON”T WALK and the HAWK lights turn off and go dark.

As a reminder, a clearance interval is the time it takes for, in this case a pedestrian, to complete their maneuver across the intersection. It’s timed, basically so that someone who steps off the curb during the WALK signal will have enough time to cross the road before the DON”T WALK turns solid and cars try to run you over. You’ll notice in some places that pedestrian signals have about 4 microseconds of WALK before going to the flashing DONT WALK. That is because engineers like me want to maximize the amount of time for vehicles in places where there is very low pedestrian traffic.

So the HAWK is for pedestrians. Does it work? Yes it does.

This device was an experiment installed by the City of Tuscon, Arizona during the 90′s. They installed a bunch of them and were very happy. The FHWA started looking at using these as a standard in the Manual on Uniform Traffic Control Devices, and in 2007 it was recommenced that they be included. The most recent edition of the MUTCD in 2009 has the HAWK as an option that can be installed, but again they call it the Hybrid Pedestrian Beacon. Boooooring.

As a part of the whole process, the FHWA also commissioned a study, which I’ll link to in the show notes, entitled Safety Effectiveness of the HAWK Pedestrian Crossing Treatment. The results of their before/after safety analysis was that there were statistically significant reductions in Total Crashes and in Pedestrian Crashes. There was also a reduction in Severe crashes, but that value was *not* statistically significant. Total crashes dropped by 29% and Pedestrian Crashes by 69%.

So, does it work. Yes, it works.

You might start seeing these installed in your area. If you happen to live in Metro Atlanta, you can already see some installed around DeKalb county. And if you live in Tuscon, this is old hat.

Thanks for listening to this episode of talking traffic. If you liked what you heard, please drop a line to Bill at talkingtraffic.org. Or you can leave a comment on the shownotes. This episode is released under a creative commons attribution non-commercial share alike license. You may use this podcast for your own, non commercial use and even change it if you care to, but please give me and talking traffic credit.

The music you hear is by Five Star Fall and can be found at Magnatune.com.

Until next time, have a good week.

If you had asked me yesterday, “Bill, can you prevent pedestrians from crossing a bridge during construction?” my answer would have been “Sure.” And I would have been wrong wrong wrong:

From the 2009 Manual on Uniform Traffic Control Devices (MUTCD):

04. If the TTC [Temporary Traffic Control] zone affects the movement of pedestrians, adequate pedestrian access and walkways shall be provided. If the TTC zone affects an accessible and detectable pedestrian facility, the accessibility and detectability shall be maintained along the alternate pedestrian route. [emphasis added]

Aha! This has implications because on one of my projects. I am proposing to close a bridge across an interstate for a weekend. During this time, I have to figure out how to get people over, under, around, or through the construction.

One idea is to set up a van shuttle from one side to the other, using the detour route. We shall see.

I had not been aware of that particular mandate in this most recent version of the MUTCD. Just goes to show that even “experts” don’t always know everything.