Headings | Traffic on Primary Road System

Route	2016	Rural/Municipal	Section length (miles)	Annual average daily traffic	Vehicle classification distribution of annual average daily traffic											Average daily vehicle miles
					Motorcylces	Cars, vans and pickups	Total trucks and buses	Single unit trucks				Combination trucks				All vehicles	Trucks and buses
	Primary route section description
								Buses	2Axles	3Axles	4 or more axles	4 or less axles	5Axles	6 or more axles	Multiple trailers

Term	Description
Route	The official route numbers assigned to all Interstate, United States and Iowa routes in Iowa. Route sections that have two or more assigned primary route numbers are listed as follows.
	Two interstate routes -interstate with lowest route number Any interstate and primary route -with interstate route Two U.S. routes -U.S. route with lowest number U.S. and Iowa route -with U.S route Two Iowa routes -Iowa route with lowest route number
Section description	A general description of the route section. Special messages are not indented, general descriptions are indented two spaces. If the traffic volume has been estimated an asterisk(*) will be shown.
Rural/Municipal	R = Rural       M = Municipal
Section length	The length of the described highway section shown to the nearest 1000th of a mile.
Annual average daily traffic	General unit of measure for traffic, which represents the annual average traffic per day (AADT). It is established by adjusting periodic counts to AADT by using factors derived from permanent continuous automatic traffic recorders.
Vehicle classification	The distribution of vehicle types that could be expected on a typical day.
Average daily vehicle miles	The product of the section length times the annual daily traffic. A separate average daily vehicle miles has been computed for trucks and buses. Pickups and vans are not considered trucks. Vehicle miles of curves, loops, connections and inner legs not considered on the traveled way are used to calculate the mainline vehicle miles and average daily traffic totals.