Quarterly Reports

For District report inquiries, contact the corresponding MPR District Staff (PDF).

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Quarterly MPR Statistics (Data Source: PeMS 14.x)

(See "Explanation Notes" at bottom of page. All files are PDFs.)

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Explanation Notes:

• PeMS data for the 2014 reporting year and future years are based on a different speed algorithm from the one used in former PeMS versions. The reports based on the new speed algorithm show marked differences in delay for most districts from the reports prepared for the previous reporting years, based on a comparison of 2013 data in both PeMS versions.

• PeMS data for the 2013 reporting year and prior years were based on a different speed algorithm from the one used in the current PeMS version 14.0 released on April 29, 2014. The reports based on the old speed algorithm show marked differences in delay for most districts from the reports prepared for the 2014 reporting year, based on a comparison of 2013 data in both PeMS versions.

• The magnitude of the difference in each district is presented in tabular and graphical comparisons in the Data Source tab. The change in speed algorithms was undertaken to provide more accurate speed estimation, more accurate aggregation over lanes and over time, and more accurate long term trends calculations. Read the release notes for PeMS 14.0. (PDF)

• Although the data are different for most measures of congestion, VMT is largely the same. The upward trend in delay continues, but the 2014 baseline is lower than the former baseline for most districts except District 7, based in Los Angeles. Smaller adjustments in "g-factors" have been ongoing systemwide since before 2005 to maintain detector accuracy.

• Delay trends and levels should be compared within the versions, not between. Therefore, the quarterly reports will be kept separate.

• 2015 and 2014 quarterly reports are provisional and subject to future revision. Data are downloaded from PeMS and entered into an Excel workbook that cross-checks the data obtained from PeMS. Any discrepancies between PeMS queries are forwarded to PeMS staff to reconcile. Discrepancies can be caused by PeMS software errors, changes in detector county of assignment, disabled detectors, change of detector type, and detection configuration updates provided by district staff. Reconciliation is the step required to ensure that all delay recorded is associated with the correct freeway and county, and in the correct amount. Finalized reports are comprised of reconciled data; thus, the reports may differ from data obtained directly from PeMS.