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</UL>



<UL>

<LI><FONT FACE="Arial">Texas DOT has built several projects using asphalt

binders that meet the Superpave binder specification. Darren Hazlett of

Texas DOT says, &quot;Using the conservative assumptions that 25 percent

of the asphalt Texas now uses doesn't meet the specification and that pavement

life will gain about 2 years where we use binders that meet the Superpave

specifications, I came up with an extremely rough estimate of $2.2 billion

in savings over 30 years.&quot; </FONT></LI>

</UL>



<P>

<HR WIDTH="100%"></P>



<P><FONT FACE="Arial">TTI's analysis included consideration of the following

factors: </FONT></P>



<UL>

<LI><FONT FACE="Arial">Highway agencies in the United States spend $10

billion on hot-mix asphalt annually. </FONT></LI>

</UL>



<UL>

<LI><FONT FACE="Arial">Traffic loads and volumes are expected to increase

by 2.1 percent annually. </FONT></LI>

</UL>



<UL>

<LI><FONT FACE="Arial">Studies by Texas DOT found that one-fourth of its

overlay projects do not use the right grade of binder for the conditions

at the project site. By converting to the Superpave binder specification,

the DOT expects those overlays to last 50 percent longer. In its analysis,

TTI used a more conservative estimate of a 25 percent increase in pavement

life. </FONT></LI>

</UL>



<UL>

<LI><FONT FACE="Arial">Based on early projects, Superpave binders are,

on average, more expensive than other grades of binders, increasing the

cost of overlays by about 7 percent. </FONT></LI>

</UL>



<UL>

<LI><FONT FACE="Arial">As States implement the Superpave system, they will

have higher upfront costs for purchasing and maintaining equipment and

for employee training. These costs were subtracted from the projected benefits.

</FONT></LI>

</UL>



<UL>

<LI><FONT FACE="Arial">The cost savings to motorists are based on reductions

in delays and in vehicle operating costs, which result from improved pavement

condition. </FONT></LI>

</UL>



<UL>

<LI><FONT FACE="Arial">The cost savings to highway agencies are based on

longer pavement life, which reduces the frequency of overlays. For example,

over a 40-year period, a roadway would require four overlays built with

a Superpave-graded binder, as opposed to five overlays built with a conventional

binder.</FONT></LI>

</UL>



<P>

<HR WIDTH="100%"></P>



<P><IMG SRC="paver397.JPG" HEIGHT=188 WIDTH=279></P>



<P><FONT FACE="Arial">By producing longer-lasting pavements, the Superpave

system can stretch highway dollars and save motorists time and money.</FONT></P>



<P>

<HR WIDTH="100%"></P>



<P><B><FONT FACE="Arial">What Makes the Superpave Binder Better than Conventional

Grading Systems?</FONT></B></P>



<P><FONT FACE="Arial">Traditionally, engineers have tested binders for

characteristics such as viscosity or penetration. These tests do not measure

a binder's low-temperature properties. As a result, highway agencies do

not always choose the best binder for a job. The Superpave binder specification,

in contrast, classifies binders according to the pavement temperatures

under which they will serve. </FONT></P>



<P><FONT FACE="Arial">The Superpave binder specification sets forth the

physical properties that all binders must have; what varies, however, is

the temperature at which those properties are reached. The properties indicate

a binder's ability to resist rutting and low-temperature cracking. </FONT></P>



<P><FONT FACE="Arial">Pavement designers determine the pavement temperatures

expected at the project site and then select the appropriate Superpave

binder grade. For example, a Superpave binder classified PG58-22 will meet

the required physical properties at pavement temperatures ranging as low

as -28 &ordm;C (-18 &ordm;F) and as high as 58 &ordm;C (136 &ordm;F). </FONT></P>



<P>

<HR WIDTH="100%"></P>



More detailed information on the benefits-versus-costs

analysis of the SHRP products, as well as more than 100 case studies

of how highway agencies are using those products, are available at the

<A HREF="http://www.ota.fhwa.dot.gov/roadsvr">RoadSavers home page</A>. 



<P><A HREF="37toc.htm">Back to <B><FONT SIZE=+1>March 1997 - List of Articles</FONT></B></A></P>



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