This article says that the permits to drive into Beiing from neighboring Hebei province will need to be renewed every 3 days.
machine translation -
Hebei Police: Beijing permit two sessions will soon effectively shortened to 3 days
http://www.chinareviewnews.com 2012-02-24 12:17:41
In the agency, Beijing, February 24 / security, Hebei Province, two of the country this year from February 28 in full swing. Hebei Daily reported that the provincial highway traffic police prompted the majority of drivers, vehicles to Beijing to carry a driver's license and driving permit. Need to enter the Fifth Ring Road (inclusive) other towns within the road vehicle, to ensure that the records off-site in Beijing, traffic violations, and with the relevant documents for Beijing card, in strict compliance with the daily and during the two sessions of the traffic control measures; Beijing Pass valid from 7 days to be shortened to three days.
Zhttp://www.chinareviewnews.com/doc/1020/2/0/9/102020918.html?coluid=45&kindid=0&docid=102020918& mdate=0224121741
machine translation -
Hebei Police: Beijing permit two sessions will soon effectively shortened to 3 days
http://www.chinareviewnews.com 2012-02-24 12:17:41
In the agency, Beijing, February 24 / security, Hebei Province, two of the country this year from February 28 in full swing. Hebei Daily reported that the provincial highway traffic police prompted the majority of drivers, vehicles to Beijing to carry a driver's license and driving permit. Need to enter the Fifth Ring Road (inclusive) other towns within the road vehicle, to ensure that the records off-site in Beijing, traffic violations, and with the relevant documents for Beijing card, in strict compliance with the daily and during the two sessions of the traffic control measures; Beijing Pass valid from 7 days to be shortened to three days.
Zhttp://www.chinareviewnews.com/doc/1020/2/0/9/102020918.html?coluid=45&kindid=0&docid=102020918& mdate=0224121741