A. General Characteristics
Arterials are designed to provide a high degree of mobility and generally serve longer vehicle trips to, from, and within urban areas. The arterial system interconnects major urban elements such as the Central Business District, industrial facilities, large urban and suburban commercial centers, major residential areas, and other key activity centers.
Movement of people and goods, also known as "mobility," rather than access to adjacent land uses, is the primary function of an arterial street. Arterial streets serve a citywide function and are, therefore, designated using a broader citywide perspective. Arterials are not planned on a neighborhood level since the result would be discontinuity and a breakdown in the street’s citywide or regional function.
Posted speed limits on arterial facilities generally range between 30 and 45 mph, varying based on the type of area being served. Higher-density central business usually accommodate businesses usually accommodate the lower end of the speed range, while higher speeds are found on facilities in outlying areas.. Traffic volume and capacity of an arterial street are dependent, in part, on the number of through and turning lanes, signalization, the number of driveways and access points, and the volume of bus and truck traffic., The volumes and capacity of arterials can range from 10,000 vehicles per day on a two-lane arterial to 75,000 vehicles on a six-lane arterial.
With an emphasis on mobility, an arterial facility is generally designed to accommodate vehicle trips in the form of passenger cars, trucks, and buses. Bicycle facilities may be provided. Pedestrian facilities are always provided, but the width of these facilities varies depending on adjacent land use and the level of pedestrian activity.
B. Definition Criteria
Historically, Denver designated streets as arterials based on certain criteria. The LUTP further refines the criteria used to designate the class of a street and, in some cases, changes the classification of particular streets to better reflect their actual function. The criteria for arterial street classification are a combination of quantitative and subjective measures that are applied to both existing and future characteristics of arterial streets. Not all of the criteria need to be met in designating an arterial street, and some criteria carry more weight than others. The following criteria are listed in order of relative importance or weight:
- Consists of a grid of streets generally spaced at 1 to 1.5 mile intervals;
- Serves as a significant street citywide, accommodating trips of 5-10+ miles between Denver neighborhoods, employment and retail centers, including Downtown;
- Provides connectivity between other arterials (e.g. connects parallel north-south or east-west arterials);
- Provides connectivity between or to freeway interchanges;
- Accommodates existing or future average daily traffic volumes of 20,000 or greater (individual segments may accommodate lower volumes);
- Provides significant restrictions on driveways and other access points to adjacent land uses;
- Accommodates the regional transit system usually providing bus service at frequencies of 30 minutes or less during peak hours;
- Operates and is designated as an arterial street in adjacent jurisdictions;
- Generally accommodates speeds of 30 mph or greater;
- Provides traffic signals at major intersections and driveways, generally spaced at 1/3- to 1/2- mile intervals;
- Functions as a significant snow, truck, or emergency route;
- Provides 4 or more travel lanes; and
- Serves higher-density and higher-intensity land uses adjacent to the street.
C. Special Criteria for Arterials within Travel Corridors
For the purposes of functional classification, a travel corridor is defined as a street, or series of closely spaced parallel streets, that operate as a system. In general, the streets in a travel corridor provide the same function or provide complementary functions. One example is a pair of one-way streets that operate as a couplet. In addition to the criteria listed above, the following criteria are used to identify arterial streets within travel corridors:
- Streets that are parallel to major, or regionally significant transit corridors, with parallel streets providing additional vehicular capacity;
- Streets that are part of a one-way couplet system; and/or
- Streets in corridors where the traffic count of the cordon (line drawn across several streets at a given point) exceeds the vehicular capacity of one of the streets.