Error in re-building vignettes:
  ...
Warning in engine$weave(file, quiet = quiet, encoding = enc) :
  Pandoc (>= 1.12.3) and/or pandoc-citeproc not available. Falling back to R Markdown v1.
Files identified: dftRoadSafetyData_Accidents_2017.zip

   http://data.dft.gov.uk.s3.amazonaws.com/road-accidents-safety-data/dftRoadSafetyData_Accidents_2017.zip
Attempt downloading from: 
trying URL 'http://data.dft.gov.uk.s3.amazonaws.com/road-accidents-safety-data/dftRoadSafetyData_Accidents_2017.zip'
Content type 'application/x-zip-compressed' length 3997883 bytes (3.8 MB)
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downloaded 3.8 MB

Data saved at /tmp/Rtmp5Waa_o/dftRoadSafetyData_Accidents_2017/Acc.csv
Reading in: 
/tmp/Rtmp5Waa_o/dftRoadSafetyData_Accidents_2017/Acc.csv
Linking to GEOS 3.6.3, GDAL 2.2.4, PROJ 5.1.0

Attaching package: 'dplyr'

The following objects are masked from 'package:stats':

    filter, lag

The following objects are masked from 'package:base':

    intersect, setdiff, setequal, union

Files identified: dftRoadSafetyData_Casualties_2017.zip

   http://data.dft.gov.uk.s3.amazonaws.com/road-accidents-safety-data/dftRoadSafetyData_Casualties_2017.zip
Attempt downloading from: 
trying URL 'http://data.dft.gov.uk.s3.amazonaws.com/road-accidents-safety-data/dftRoadSafetyData_Casualties_2017.zip'
Content type 'application/x-zip-compressed' length 1169376 bytes (1.1 MB)
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downloaded 1.1 MB

Data saved at /tmp/Rtmp5Waa_o/dftRoadSafetyData_Casualties_2017/Cas.csv
Files identified: dftRoadSafetyData_Vehicles_2017.zip

   http://data.dft.gov.uk.s3.amazonaws.com/road-accidents-safety-data/dftRoadSafetyData_Vehicles_2017.zip
Attempt downloading from: 
trying URL 'http://data.dft.gov.uk.s3.amazonaws.com/road-accidents-safety-data/dftRoadSafetyData_Vehicles_2017.zip'
Content type 'application/x-zip-compressed' length 2584589 bytes (2.5 MB)
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downloaded 2.5 MB

Data saved at /tmp/Rtmp5Waa_o/dftRoadSafetyData_Vehicles_2017/Veh.csv
Joining, by = "accident_index"
Quitting from lines 256-267 (blog.Rmd) 
Error: processing vignette 'blog.Rmd' failed with diagnostics:
cannot open the connection
Execution halted