You are getting away for a long weekend in the White Mountains. Or maybe you are coming back from a vacation at Rocky Point. Either way, you are on the highway and wondering how much longer until you reach your destination.

Then, a little farther down the road, you see a familiar green shape. It's a sign letting you know that you are now X miles from Pinetop-Lakeside or have Y miles left to get to Phoenix.

Distance signs are an essential part of the state highway system, but how much have you ever thought about them? Questions that occasionally pop up on our social media include why signs list the destinations they do, or what points are those signs measuring to exactly? If that is something that's ever crossed your mind, here's a primer about how exactly distance signs get the job done.

It all starts with which cities to show. Distance signs can show up to three destinations, with the bottom slot reserved for what are known as "control cities."

A control city is defined in Section 300 of our Traffic Engineering Guidelines and Processes as one containing a junction of two or more state or federal highways. A control city also can be one whose location can be easily determined by highway users, is on the state highway map and "whose population and character are generators of sufficient traffic to be a focal point for travel." Control cities for an interstate must meet similar qualifications, with the added stipulation that they be cities of "national significance." 

The listed control city for a route should remain the same along the entire highway until that destination is reached. If there are two cities of equal significance, they can be displayed on alternating boards.

Above control cities go intermediate destinations, which must have at least one motorist service, be a traffic generator that the highway was built to service or be an important route junction. If there are two such cities along the route, both can be shown.

On a rural freeway, the top line should be reserved for the next community the freeway will pass through or the next major highway junction. After that, the next intermediate destination should be displayed. Finally, an upcoming rest area also can be listed in the top or middle slot, if desired.

So we have our destinations. But when the sign says X miles to Payson, where exactly are they measuring to?

This one is a bit easier to answer. The guideline and processes say the distance shown should be to the center of the destination, rounded to the nearest mile. And what exactly constitutes a "center?" It could be anything deemed to be significant near the center of the community, such as a major railroad junction, business district, post office, city/town hall or something similar. 

In case a new sign is needed, our Guidelines and Processes reference has extensive tables listing control cities and other communities along any given state highway, plus mileage figures between the state line and destinations in neighboring states and Mexico.  

And there you have it. You may not remember this the next time a helpful green sign lets you know you still have X miles left to Prescott or Y miles until Bisbee, but it's a good thing to have handy just in case anyone in the car asks. Drive safe out there!

 

Have you ever wondered why 411th Avenue in Tonopah is Exit 95 off Interstate 10? Or why if you are turning on to Dragoon Road in southeastern Arizona you take Exit 318?

Or how about using Exit 67 to get to Dateland from Interstate 8, or Exit 322 on Interstate 17 to get to Munds Park?

The answer is deceptively simple: It's all about mileposts.

So, quick background: Mileposts for an interstate start at "0" at either the western or southern state line, and increase as you head in the opposite direction, according to the Federal Highway Administration's page on its website about the interstate system. (The exception in Arizona being I-17 doesn't start at "0" because it took over its alignment and mileposts from the original State Route 69, but that's another story.)

As you head either east or north, the first exit you come to is numbered by the milepost immediately west or south of it. So if an exit is at milepost 8.7, it would be signed as Exit 8. If the next is at milepost 15.2, it will be Exit 15. And so on and so forth. And in case there are multiple exits at the same junction, like in the photo here, you use sequential letters to differentiate the ramps.

Sounds simple, right?

Except that's not always true countrywide. Some states, mostly in the East, don't use a milepost numbering system but rather a consecutive numbering system for their exits. So, coming from the west or south the first exit will always be Exit 1 and the next – no matter how far away – would be Exit 2.

However, the milepost system (or properly the reference location system) is the Federal Highway Administration's preferred way of numbering exits. In the 2009 revision of the Manual of Unified Traffic Control Devices (the federal guidelines for all things highways such as signs, pavement markers, signals, etc.), language was added saying, "Interchange exit numbering shall use the reference location sign exit numbering method. The consecutive exit numbering method shall not be used."

In Section 2E.31, paragraphs 4 and 5, the manual goes onto say why FHWA prefers this over the consecutive method: "Reference location sign exit numbering assists road users in determining their destination distances and travel mileage, and assists highway agencies because the exit numbering sequence does not have to be changed if new interchanges are added to a route"

 

By John Halikowski / ADOT Director

It shouldn’t be a surprise to anyone that transportation plays a key role in a state’s economy. A good transportation system ensures that goods and services get to their proper destination. A good transportation system ensures people get to where they want to go either for business or pleasure. At the Arizona Department of Transportation, we continue to make improvements in our state transportation system that ensure trade flows between our borders and people can travel to their favorite destinations. Here’s what we have planned this year that keeps Arizona’s economy moving:

The biggest single transportation project in the state’s history is the Loop 202 South Mountain Freeway. The $1.9 billion project begins in earnest in the first half of 2017 with the building of the foundations for 40 bridges planned, widening eastbound lanes on Pecos Road, and access roads near Interstate 10 in west Phoenix. The 22-mile project is a direct link between the East Valley and the West Valley, and it brings great economic development opportunities.

Pavement preservation is a cornerstone in keeping our transportation system functioning at its best. We have an 11-mile stretch of I-17 scheduled for resurfacing in the spring of 2017. Between 19th and Peoria avenues, our crews will add a new layer of smooth, durable rubberized asphalt along the Black Canyon Freeway.

A widening project in the Marana/Tucson area will improve travel along Ina Road and Interstate 10. The $120 million project features a wider bridge with two lanes in each direction over I-10 and the railroad tracks, making the area more efficient and safer to travel.

Dust storms are very prevalent in Arizona especially during our summer monsoon season. ADOT was awarded a $54 million federal grant in 2016. A portion of the grant funds are being used to install a dust detection and warning system along I-10 between Eloy and Picacho Peak later this year. When fully implemented, the system will trigger safety measures including reduced speed limits and electronic message boards to warn drivers of visibility concerns. We will continue our efforts to warn drivers not to drive through a dust storm.

Our interstates serve as key commerce corridors in Arizona. Roadway improvements, whether they are additional lanes, paving or a dust detection system, ensure our transportation system is working efficiently and effectively. At ADOT, we are committed to making sure our state’s economy continues to move at the speed of business.

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This post originally appeared on ADOT Director John Halikowski's
LinkedIn page. He has led the agency since 2009.

 

By Steve Elliott / ADOT Communications

We let you know recently about an opportunity to help chart our transportation future through the National Household Travel Survey if yours is among up to 30,000 Arizona households invited to participate. For those who aren't invited, we've set up our own online survey so everyone can share their travel story.

Today we're sharing a public service announcement on these surveys featuring ADOT Director John Halikowski. Please check it out and see how you can provide information that will help guide decisions not just on freeways and bridges but public transportation, bikeways and even sidewalks.

On Friday (June 19), the State Transportation Board met in Pinetop-Lakeside and voted to adopt the 2016-2020 Five-Year Transportation Facilities Construction Program…

That means projects designed to preserve, modernize and expand Arizona’s highway system now have formal approval to move forward as part of ADOT’s annual five-year planning process.

You might remember that we blogged about the start of the process back in March, when ADOT made a call to the public for comments on the plan. Since that time, ADOT has held three public hearings and has collected email, phone and online comments.

If you’ve been reading the blog for a while, you know that the plan acts as a blueprint, detailing where, when and how funding (that includes regional, state and federal money) will be spent for future ADOT projects. It gets updated annually and when finalized, it helps ADOT to prioritize which projects move forward first. Funding for the Five-Year Program is generated by the users of transportation services, primarily through gasoline and diesel fuel taxes, and the vehicle license tax.

New 2016-2020 plan

Much like the current Five-Year Program, the newly adopted 2016-2020 Five-Year Program reflects a major focus on preserving the existing state highway system while moving some high-priority expansion projects forward. ADOT must prioritize projects due to continued low revenue from the gas and vehicle license taxes and from decreased federal funding — all of which support the Five-Year Program. ADOT’s continued focus on preservation allows the department to protect its investment of $19.7 billion in the state highway system. Without a commitment to preservation, it would cost approximately $200 billion to replace the system.

Both the Maricopa and Pima county regions in the two metropolitan areas have independent revenue streams established through voter-approved sales tax increases that allow for more expansion projects to take place and for more transportation funding overall.

Please check out ADOT’s recent news release, for an overview of major projects in Greater Arizona, the Maricopa Association of Governments (MAG) region and the Pima Association of Governments (PAG) region during the 2016-2020 Five-Year Program.

You can also view the entire plan, along with an outline on transportation planning on our website.