In This Issue...

Street and Roadway Solutions

We Hear You
Take Control
Cut Congestion with Concrete Roundabouts
Concrete Pavement Restoration Provides Top-Notch Service
Concrete Makes It Easy to Be Green
Small-Area Overlays Result in Big Savings
Transportation News

You may be a city planner, a local government official, or a municipal engineer, but one thing you aren't is a magician. So why are you expected to solve everything at the flip of a coin, and with less money in the budget?

"Traffic matters are very emotional and traffic professionals are often the target of residents' backlash," said Steve Cope, Transportation & Traffic Services Operations Manager for the City of Naperville, Illinois, which sits just 28 miles northwest of Chicago.

Having worked for the City for 26 years, 25 1/2 spent in transportation services, Cope knows a thing or two. One of the greatest challenges, he says, is the growth in population. In his time with the city, the population has boomed from less than 40,000 to nearly 140,000 residents.

"Surrounding communities are growing rapidly," he said. "It is quite difficult to keep up with traffic-related demands."

Cope is one of many officials responsible for keeping residents satisfied in one way or another in their communities. The challenges these urban and metropolitan planners face aren't new, but they grow in complexity everyday as the number of residents surges.

By 2008, more than half the world's population of 3.3 billion people will be concentrated in urban settings for the first time in history, according to a United Nations Population Fund report.

In the United States alone, the population has seen the largest increase in the nation’s history between 1990 and 2000 – a 32.7 million person increase, according to Census 2000.

The concrete pavement industry understands this means growing responsibilities for urban planners and offers a number of solutions to lift the transportation services burden from their shoulders.

Whether the greatest demand lies in reducing congestion, beautifying local roadways, or restoring streets to like-new condition, this issue of CONCRETE PAVEMENT PROGRESS features solutions for your community.

Read on to learn more about how concrete pavement can save time and

as well as environmental and aesthetic benefits to communities.

Sound off: click here to drop ACPA a line and describe the challenges you face, or how your community is coping.

Local agencies are faced with more motorists to accommodate on streets but less money to do it with.

Officials can gain control in this budget crunch by spending the funds allocated to them on longer-lasting, durable pavements.

Many in the past have turned to asphalt, thinking that its initial price tag would make it the best choice. However, asphalt was rarely cheaper than concrete pavement in the long term, and now, with rising oil prices, it is often higher at first cost than an equivalently designed concrete pavement.

The net effects of less repair and maintenance are more traffic jams, no relief from dangerous driving conditions, and more vehicle repairs. Concrete pavements have historically provided the best value over time because they require virtually no maintenance and fewer repairs than asphalt.

And because the materials necessary to construct them are natural and abundant (see related article "Enlightened Communities"), concrete pavements is even less expensive for agencies.

LCCA compares the true costs of asphalt and concrete pavement, not just on initial cost but over the life of the pavement.

ACPA offers the following resources for conducting LCCA:
• Click here to download a free copy of "Lasting Impressions," part of the Association's popular Quick & Direct literature series.
• Click here to order your copy of StreetPave design software for streets and roadways.

Questions? Contact Scott Haislip at 219-922-8104.

In recent studies conducted by the National League of Cities, one of the main concerns facing local governments was growing congestion. Many of these problems were associated with signalized interchanges.

Enter concrete pavement roundabouts. In these bottlenecked areas, they have been proven to not only reduce congestion but also provide enhanced safety.

Traffic calming is one area that all city officials agree needs to be addressed, especially in areas that must accommodate vehicles, pedestrians, and bicycles.

"Some residents require a lot of staff time because of the threat the upper 15 percentile of traffic poses to their quality of life," said Steve Cope, Transportation & Traffic Services Operation Manager for the City of Naperville, Ill. "Trying to maintain roadways that are smooth and pleasant to drive as opposed to lumpy and frequently stopping travels is a significant challenge."

Concrete pavement has long been specified in intersection design and construction because of they resist shoving and rutting, especially where there is slow maneuvering cars and trucks. Concrete withstands these pavement stresses, which cause deterioration requiring frequent repairs.

ACPA Offers Pavement Thickness Design Tips for Concrete Roundabouts

The two primary design aspects for roundabouts is pavement thickness design and jointing system design.

In most pavement thickness design procedures, designing the pavement structure requires, at minimum, determining the following factors:

• Concrete Properties – Flexural strength or modulus of rupture, MR; and modulus of elasticity, E.
• Support Conditions – Strength of the subgrade, or subgrade-subbase combination (modulus of subgrade reaction, k).
• Desired Life – Design period, which is typically 20 years, but may range from less than 5 to more than 50 years.
• Expected Traffic – The weights, frequencies, and types of truck axle loads that the pavement will carry during the design period.
• Design Features – Use of dowels for load transfer at transverse joints, and provision of edge support along slab edges.
• Reliability – As it relates to the predicted number of cracked slabs at the end of the design life.

Because a roundabout carries traffic from two or more roadways, the concrete slab thickness may need to be greater than the thickness on the approaching roadways.

For roundabouts and traditional intersection pavements, typical concrete thicknesses can range from 5 to 10 inches (125 to 250 mm). The exact required thickness will depend on expected traffic, local conditions, past history, and other factors. Additionally, designing and laying out the single and multiple lane roundabouts using rideable raised medians and islands will allow large trucks to easily navigate the interchange.

ACPA is nearing completion on a new publication with updated construction and design practices for concrete pavement roundabouts. For more information, contact Scott Haislip at 219-922-8104.

The key to any preservation strategy is timing. Planning a CPR project needs to begin at approximately the two-thirds to three-quarters of the pavements design life. This ensures that both maintenance funding and project plans and specifications are prepared before extensive deterioration has occurred, when the project may warrant a concrete overlay or full reconstruction.

Pavement Evaluation

Evaluating the current pavement condition and anticipating the additional pavement fatigue is the first step in developing a successful, integrated pavement management strategy. Important considerations in evaluating pavement condition are:

1. Design Data
2. Construction Data
3. Traffic Data
4. Environmental Data
5. Previous CPR Activities
6. Pavement Condition

After the pavement engineer has all the pavement data, he or she must answer four questions:

1. Which distresses are present?
2. What caused the distresses to develop?
3. What are the viable solutions to correct the distresses in the pavement or prevent their return?
4. Is the timing appropriate for these solutions to be effective and economical?

Applying the proper techniques or procedures for the pavement condition at the proper time is essential for good CPR performance.

100% Natural, 100% Recyclable

Unlike asphalt pavements that rely on costly non-renewable oil supplies, concrete pavements are made from three abundant, readily available ingredients: water; rocks (stone, sand, and gravel); and cement (made from plentiful natural minerals).

The concrete and cement industries also rely on materials from other industrial processes that are diverted away from landfills.

Slag (which comes from the steel industry) can be used to partially replace rocks.

Also, fly-ash (that comes from the power industry) or ground blast-furnace slag can be used to replace as much as half of the cement used in concrete.

Even the process of making cement uses recycled materials. High-energy waste, such as scrap tires, can be safely used as fuel for the cement-making process. For example, each year, a single cement kiln can use 1 million scrap tires, conserving fossil fuels and reducing waste.

Bright Idea

In addition to its natural and recyclable qualities, concrete pavement lights up streets and cools it off for energy savings.

Pavements, sidewalks, and parking lots are brighter at night when made with concrete instead of asphalt. Up to 27% of light falling on a concrete surface will be reflected, compared to as little as 5% of light from asphalt pavements. This saves energy and offers real safety benefits, too.

In urban areas, concrete also reduces the heat-island effect, a phenomenon associated with dark pavement and roof surfaces that cause temperature increases.

The urban heat-island effect can contribute significantly to both energy consumption for air conditioning and to smog formation.

Extra Features

While concrete pavement inherently contains qualities that make it the environmental pavement type of choice, there also are a range of different types of concrete pavement that hold extra benefits.

One of these is pervious concrete pavement. This type is made from coarse aggregates, cement, water, and other materials that allow the pavement to reduce storm runoff and minimize the amount of pollutants typically contained in stormwater, such as motor oil, anti-freeze, and other automobile fluids. By allowing some of the rainfall to percolate into the ground, soil chemistry and biology come together to naturally treat the polluted water, which reduces the strain on wastewater treatment facilities.

Stress Relief

Concrete pavement lasts longer than asphalt pavements, meaning less repairs and reconstruction, meaning less stress on the environment because:

• fewer raw materials must be taken from the environment in the short term and over the life of the pavement;
• fewer pollutants are going into water, air, and soil;
less energy required for construction, which results in less motor fuels and oils for heavy construction equipment;
• less energy required as motorists navigate around work zones or when crews pave at night; and
• reduced traffic congestion due to fewer work zones slowing traffic flow.

ACPA offers a number of promotional and technical materials on how concrete pavement can address demand for environmental features in your community:

• Follow these links to download free copies of ACPA's Q&D's 010P: Enlightened and 016P: Natural Advantage.
• Click here to visit ACPA's bookstore and order a copy of IS334P: Stormwater Management with Pervious Concrete.

Questions? Contact Scott Haislip at 219-922-8104.

When Chicago transportation officials called on the concrete pavement industry to help with repair a busy stretch of bus pads, the end product resulted in big time and cost savings.

Five years later, the innovative concrete overlays developed are still holding strong, while the surrounding asphalt pavement is already showing rutting and shoving.

In 2002, the wear and tear on the asphalt roadway of Western Avenue was in dire need of repair. This included a stretch of bus pads to support the hundreds of buses traveling this route each day.

The concrete pavement industry then recommended a four-inch concrete pavement section, built with a four-foot transverse by 40-inch longitudinal joint spacing. The unusual 40-inch longitudinal joint spacing was chosen to control slab size while fitting within an unusual 10-foot lane width. The dimensions of the buspads are 10 feet wide by 100 feet long.

Proper dispersion of the fibers is essential in producing a mixture that is both easy to finish and which provides the needed structural characteristics.

Though the slabs have been sized to control stresses, Cook County wanted to be sure of long life with little possibility for distresses. In response, the industry incorporated a new generation of synthetic structural fibers into the concrete mixture. The Strux 90/40 developed by W.R. Grace are specifically designed to replace mesh reinforcement. They have yielded impressive results in testing performed under the direction of Jeff Roesler, Ph.D., P.E., Department of Civil Engineering, University of Illinois at Urbana.

The fibers were added at the addition rate of 7.5 lbs. of fibers per cubic yard, a quantity significantly higher than conventional practice. Additionally, W.R. Grace provided a new fiber-insertion system for contractor, E. A. Cox, Chicago, and material producer, Aztec Material Service Corp. to use. This system “refluffs” the prepackaged bagged product and blows them into the ready-mix truck before charging the drum. This ensures adequate distribution and minimizes the likelihood of fiber “balling," a common problem when large quantities of fibers are used in a mixture.

The industry and agency have inspected the bus pad's performance each year since their placement. The bus pads not only cost two thirds less than the full-depth concrete replacement option, but they have stood up to the hundreds of buses they bear each day and required no maintenance. The adjacent asphalt pavements, however, can't claim the same: they are already showing significant distress.

The kicker: this concrete pavement overlay system cost two-thirds less the price of the full-depth concrete replacement option.

For more information on how to incorporate this procedure for bus pads in your area, contact Randell C. Riley, P.E., Executive Director/Engineer, or Jimie Wheeler, Promotional Director - Northern Illinois, with the Illinois Chapter, Inc.—ACPA.

For the first time, the Transportation Research Board is offering companies with transportation-related products and services to exhibit at or sponsor its annual meeting.