library(bigrquery)
set_service_token('access_token.json')

tb <- bq_dataset_query(
   x = ds,
   query = sql,
   billing = '{your billing project}',
   use_legacy_sql = use.legacy.sql,
   parameters = params
)
dt <- bq_table_download(tb)

# set env var `BIGQUERY_ACCESS_TOKEN_PATH` to path of your token file.
devtools::install_github(madedotcom/retl)
library(retl)
library(data.table)
dt <- bqExecuteQuery(sql)