HomeMy WebLinkAboutCT 13-03; ROBERTSON RANCH-RANCHO COSTERA; PAVEMENT ALTERNATIVES; 2013-05-23Andrew T. Guatelli, GE 2320
John P. Franklin, CEG 1340
Pavement Alternatives, El Camino
FROM:
May 23, 2013
Shapell Homes, Attention: Darius
O'day Consulting, Attention: Ge9j
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DATE:
TO:
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Geotechnical h Geblogic . Coastal . Environmental
5741 Palmer Way • Carlsbad, California 92010 • (760) 438-3155 • FAX (760) 931-0915 s w.peosoilsinc.com
MEMORANDUM
Reference: "Geotechnical Investigation for the Planned Improvement of El Camino Real,
Between Cannon Road and Tamarack Avenue, Rancho Costera (Formerly
Robertson Ranch West Village), Carlsbad, San Diego County, California,"
W.O. 6145-E-SC, dated May 11, 2011, by GeoSoils, Inc.
The description of pavement distress was presented in the referenced GSI report, and is
repeated below, in italics, for ease of review.
Pavement Distress
Existing pavement distress was noted throughout the northbound pavement area, and is déscribedas follows:
Alligator (Fatigue) Cracking:
The most prevalent type of pavement distress appears to be alligator, or fatigue cracking. Alligator cracking
is a series of interconnected cracks caused by fatigue failure of the HMA (hot mix asphalt) surface under
repeated, excessive traffic loading, due to poor drainage, weak base or subgrade (Asphalt Institute
(htto:I/asDhaltinstitute. oraIublicIenaineeringIindex.aspl). As the number and magnitude of loads becomes
too great, longitudinal cracks begin to form (usually in the wheelpaths). After repeated loading, these
longitudinal cracks connect forming many-sided sharp-angled pieces that develop into a pattern resembling
the skin of an alligator.
Between ECR, Stations 444+00 to 455+00, moderate alligator cracks occur within the wheel paths within the
slow lane, and/or the previous location of the slow lane prior to median construction. From Stations 455+00
to 459+00, alligator cracks appear within the wheel path nearest the bike lane, and along the approximate
location of an approximately 6-inch wide utility trench patch. This distress may also resemble block cracking.
Moderate alligatoring was again observed within the wheel path, located just outside the bike lane from
approximate Stations 464+50 to 469+50, and in the vicinity of the 6-inch wide utility trench patch. Light,
localized alligatoring was observed, primarily within the slow lane, from Stations 476+50 through Station
478+50. From Stations 486+50 to 491+50, light to moderate alligatoring was noted with the slow lane, with
light cracking also observed within the fast lane.
Based on ourreview, a greaterdegree of fatigue cracking appears to coincide with pavement areas underlain
with alluvial soils and a relatively shallow groundwater table. Other areas of fatigue cracking may also be
associated with poor drainage along the margins of the roadway, especially in the vicinity of Stations 476 + 50
to 478+50.
Patching:
Patching, or areas of pavement that has been replaced with new material to repair the existing pavement, were
observed throughout the pavement area of ECR. A patch is considered a defect, and temporary, no matter
how well it performs.
Depressions, or Rutting:
Localized depressions, or ruts were noted within the wheel path nearest the center median in the vicinity of
Stations 461+00, and between Stations 486 +50 and 491+50. Pothole also appear to be forming within these
areas.
Other:
Minor areas of polished aggregate, raveling, etc. where noted locally and are likely an indication of pavement
age. Areas of water seepage were not observed within the existing northbound ECR.
The following alternatives may be considered for the rehabilitation of El Camino Real
between Tamarack Avenue and Cannon Road. It should be noted that the design life
anticipated for these pavement repair alternatives is less than that indicated in the
referenced report for the prior recommended pavement rehabilitation, and probably less
than 10 years. The design civil and representatives of the City should assign the distressed
locations to the categories listed below.
Category 1: Existing ruts combined with alligator and large cracking -this is-considered
a potential subgrade failure - these areas will probably be completely rebuilt
into the base section using Mirafi RS380i (or equivalent), with no paving grid
or paving overlay.
Category 2: Existing pavement has little or no ruts with some moderate alligator cracking
- these areas potentially will replace 5-7 inches of existing AC (leaving 1 inch
of existing AC in place), place a high strength PGM grid product and the 5
to 7 inches of new AC over the PGM reinforcement. GSl's concern for
Category 2 is that potential damage may be caused during construction due
to insufficient strength to hold equipment without "punching" the remaining
pavement (1 inch thick existing AC left in-place). Consideration should .be
given to removing all existing AC, and use PGM-G4 with atwo lift below and
above "put back."
Category 3: Existing AC pavement, no ruts, some small fatigue cracking, minor
aggregate "pop outs" or raveling -these areas will minimally require 2 inches
removal of existing AC, place a Mirapave fabric, and replace 2 inches of new
AC over the Mirapave.
Shapell Homes W.O. 6145-E-SC
ECR Pavement Rehabilitation May 23, 2013
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