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| FHWA > Engineering > Pavements > Research > LTPP > Feedback |
GPS Feedback Report SummariesFor additional information e-mail: ltppinfo@fhwa.dot.gov. Report Number: BRE-2b Subject/IMS Table: Discrepancies in dates for
some GPS-6 sections in the TRF_BASIC_INFO
table. LTPP Analysis/Operations Situation: The date that section 086002 was opened to traffic, according to the TRF_BASIC_INFO table, is 10/1/72. The construction date, as it appears in INV_AGE, is 11/1/69. The date the layer structure changed (CN_ASSIGN_DATE) is 12/31/68. This means the overlay date was before the construction date. Sections 086013, 087781 and 087783 also have problems with the same dates. Resolution of Problem/Situation: The CN_ASSIGN _DATE and ASSIGN_DATE dates for construction number 1 will be set to 01-jan-87 for Colorado sections 6002, 6013 and 7781. This is the minimum recommended by the Technical Services Support Contractor (TSSC) in the proposed experiment section quality control (QC). Overlay dates for 6A sections are being resolved with the best available information. The 6B section (7781) had appropriate dates associated with the overlay. Report Number: ERES-BW-10 Subject/IMS Table: Need to designate GPS-2
section 872811 as a GPS-7A section. LTPP Analysis/Operations Situation: GPS section 872811 (Ontario) is designated as a GPS-2 section with the following layering: 43.2 mm hot-mix asphalt concrete (HMAC) Surface Course, 38.1 mm HMAC Binder Course, 188.0 mm Treated Base Layer (Other), 149.9 mm Lean Concrete Subbase Layer, Lean Clay with Sand Subgrade. In the film distress interpretation process it was noted that full-width transverse cracks, all skewed at the same angel and at a regular spacing of 4.57 m, are present. This is interpreted to mean that the pavement is actually an asphalt concrete (AC) surface over a jointed plain concrete pavement (LPCP) with skew joint spacing of 4.57 m. The L05B table indicates the treated base layer as "other." Recommended Action: The section should be designated as a GPS-7A section. Resolution of Problem/Situation: Test section 872811 has been re-designated as a GPS-7A. Report Number: ERES-BW-56 Subject/IMS Table: GPS-5 monitoring
adjustments. LTPP Analysis/Operations Situation: Based on the evaluation of monitoring data from GPS-5 sections (as reported in a final report recently prepared by ERES Consultants, Inc.), it appears that the 500 ft length of the continuously reinforced concrete pavement (CRCP) test sections may not be long enough to capture the representative information related to localized failures (punchouts, patches). It is strongly recommended that future distress surveys include a survey length of 3 to 5 miles of the project length to better identify the amount of localized failures. Resolution of Problem/Situation: This feedback report was not assigned for resolution since doing surveys over a three to five mile section is not practical. Report Number: ERES-BW-57 Subject/IMS Table: GPS-5 early age weather
data. LTPP Analysis/Operations Situation: CRCP cracking is significantly affected by weather conditions during construction and during the first few days. Lack of data on early age cracking due, to ambient weather conditions at the time of construction, will continue to limit the value of the GPS-5 experiment to produce meaningful data on factors affecting early-age cracking. Identify with more specificity the dates that the GPS-5 test sections were constructed. The weather conditions during the early age period can then be identified using national/local weather databases. Resolution of Problem/Situation: Date of construction is a data element in the IMS. Identifying the date with more specificity is not practical.
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This page last modified on 03/22/07 |
