Specs

Proposed Bridgestone April 20, 2011
NWC of Vance St. & W. Center Ave. PSI Project No. 532281
Lakewood, Colorado Page 11 of 15
6.4.2 Pavement Thickness Recommendations
Based on the sandy clay material encountered during our subsurface investigation, PSI has
assumed an R-value of 5 to support the proposed pavement sections if on-site soils are
used for overexcavation and replacement. If an imported structural fill material is used for
backfill during overexcavation and replacement, a higher subgrade support value can be
used. Based on the properties of the imported structural fill recommended in Section 5.2.1,
PSI has based this report on the imported structural fill providing at least an R-Value of 60
to support the proposed pavement sections if imported structural fill is used..
PSI has identified two pavement categories based on anticipated traffic use and traffic
loads. We have assigned estimated traffic loads to each category expressed in EDLA’s,
where the EDLA is the equivalent daily load applications of vehicles relative to an 18-kip
single axle load. We have also assumed the following design criteria; a 20-yr design life,
a Pavement Serviceability Index (PSI) of 2.0 and a Reliability of 85%.
PSI has assigned an estimated EDLA of 2 for the general parking stall (Light Duty
Traffic) area. Anticipated traffic in this area includes private passenger vehicles or
similar vehicles.
The drive lanes within the site have been assigned an estimated EDLA of 5 (Heavy
Duty Traffic - Drive Lanes), PSI anticipates that traffic in this area will be mixed use
consist of delivery vehicles of varying size and weight and passenger vehicles.
Pavement section options are provided for full depth asphalt, asphalt over aggregate
base course, and rigid (Portland Cement Concrete) pavement. However, it is PSI’s
experience that pavements with properly placed base aggregate on a properly drained
grade outperforms full depth pavement sections. Based on this information for the
subject pavement, the following pavement sections were determined, as presented
below.
The following table presents pavement section thicknesses if swell mitigation through
overexcavation and replacement with moisture conditioned and compacted on-site soils
is selected.
Pavement Area
Composite Section
(inches)
Full-Depth Asphalt
(inches)
Full-Depth
Portland Cement
Concrete (inches)
Light Duty Traffic
Parking Stalls
(EDLA = 2)
Heavy Duty Traffic
Drive Lanes
(EDLA = 5)
4 inches Asphalt
over
8 inches Aggregate
Base Course
4 ½ inches Asphalt
over
9 inches Aggregate
Base Course
6 ½ inches 5 inches
7 ½ inches 5 inches