Important Terms & Concepts
Circulation Element Terms & Concepts
The definitions below highlight key technical terms used in this element to discuss traffic and transportation issues.
Level of Service
The efficiency and quality of traffic operations can be described in terms of Level of Service (LOS). Six categories of LOS the letter designations A to F are used to identify traffic conditions, with LOS A representing excellent conditions and LOS F representing extreme congestion. The LOS designations correspond to volume to capacity (V/C) ratios calculated for roadways. For example, a roadway that carries 18,000 vehicles per day, with the capacity to accommodate 20,000 vehicles per day, has a V/C of 0.90.
Table C-1 shows V/C ranges and the corresponding LOS, with a description of actual traffic conditions associated with each V/C range and LOS for signalized intersections.
|Volume to Capacity Ratio||Level of Service||Description of Traffic Conditions|
|0.0 - 0.60||A||Very short delay due to random arrival of vehicles during red light.|
|0.61 - 0.70||B||Short delay of 5.1 to 15.0 seconds per vehicle.|
|0.71 - 0.80||C||Stable flow, delays of 15.1 to 25.0 seconds per vehicle. Some waiting vehicles may fail to go through the intersection before the green light turns red.|
|0.81 - 0.90||D||Average vehicle delay is 25.1 to 40.0 seconds. Congestion becomes more noticeable. Many vehicles are required to stop at the signal.|
|0.91 - 1.00||E||Unstable traffic flow, with an average vehicle delay of 40.1 to 60.0 seconds (generally perceived as the limit of acceptable delay). Most vehicles are required to wait at least one traffic signal cycle.|
|Above 1.00||F||Traffic volumes exceed roadway design capacity, resulting in forced flow, jammed intersections, long delays, and two-cycle signal waits. Average vehicle delay exceeds the acceptable 60 seconds per vehicle.|
Transportation Demand Management
A population's travel behavior strongly affects roadway congestion and peak-hour traffic in particular. The typical 8 to 5 work week deposits millions of people onto the same roadways during the same work commute hours. Transportation Demand Management, or TDM, represents one approach to modifying travel behavior, especially in the area of home to work trips. Many TDM strategies focus on increasing interest in alternative modes of transportation for work commutes, as well as developing other alternatives designed to manage, manipulate, and maximize the use of existing transportation facilities. Examples of such strategies include subsidies that encourage public transit or vanpool ridership and preferential parking for carpoolers.
Street / Highway Classifications
Roadways are defined in terms of their function and size. In Monterey Park, the public street system consists of the four roadway classifications, illustrated in Figure C-1. These classifications are:
- Principal Arterial
A Principal Arterial serves as a regional travel route, accommodating through trips and linking the local street system to through routes. In Monterey Park, Principal Arterials have a width ranging from 84 to 100 feet curb to curb within a 100 to 120 feet right of way. This street section typically provides for a four lane divided roadway or potentially six reduced-width lanes if parking is prohibited. The estimated daily capacity is 40,000 to 60,000 vehicles per day.
- Minor Arterial
Minor Arterial roadways provide a 64 to 68 feet curb to curb width within an 80 to 88t right of way. These geometrics allow for either a four-lane divided street (similar to a Principal Arterial) or a four-lane undivided roadway with a capacity up to 40,000 vehicles per day.
A Collector street, as the name implies, collects and distributes traffic from local streets to the arterial road network. A Collector has a 40 feet curb to curb width within a 60 feet right of way. A two-lane undivided roadway is the usual design, with on-street parking permitted. Collectors are designed to carry moderate levels of traffic, generally 15,000 to 25,000 vehicles per day.
- Local Street
Local streets are two-lane undivided roadways designed to serve local circulation, with traffic characterized by low volumes of vehicles traveling at slower speeds. Generally, a local street is not intended to handle through traffic. This classification provides a 36 foot curb to curb width within a 50 feet right of way, although the geometric may vary for local streets in hillside neighborhoods or neighborhoods established before the 1940s.
Bicycle Path Classifications
Bicycle travel is accommodated either on or separate from the local road network. The California Department of Transportation (Caltrans) has established three bicycle path classifications adopted by many public transportation agencies and cities.
- Class I
Bicycle paths with exclusive rights of way intended to serve cyclists with the safest means of travel.
- Class II
Bicycle lanes along the curb lane of a street or highway. The path provides for one-way travel and is generally delineated with special striping and signage.
- Class III
Bike routes for shared use with pedestrian or motor vehicle traffic. Signs are posted which indicate that the road also serves as a bike route, although no special striping is provided for cyclists.