r - 来自谷歌地图 API 的旅行时间不会随一天中的时间而变化

Question

我曾经gmapdistance计算不同时间在纽约两点之间的旅行时间。有人可以告诉我为什么旅行时间相同并且不随一天中的时间变化吗？

library(gmapsdistance)
library(lubridate)

# key is set

temp1 = gmapsdistance(
  origin = "40.75905289665592+-73.97693625311344",
  destination = "40.76264792279165+-73.99683999171252",
  mode = "driving",
  key = key,
  departure = as.numeric(ymd_hms("2021-09-11 15:00:00"))
)
temp1$Time


temp2 = gmapsdistance(
  origin = "40.75905289665592+-73.97693625311344",
  destination = "40.76264792279165+-73.99683999171252",
  mode = "driving",
  key = key,
  departure = as.numeric(ymd_hms("2021-09-11 19:00:00"))
)
temp2$Time

temp3 = gmapsdistance(
  origin = "40.75905289665592+-73.97693625311344",
  destination = "40.76264792279165+-73.99683999171252",
  mode = "driving",
  key = key,
  departure = as.numeric(ymd_hms("2021-09-11 23:00:00"))
)
temp3$Time