The standard approach to evaluating traffic impacts is based on a concept known as “Level of Service” or “LOS.” This metric evaluates congestion on streets and intersections based on the capacity of a street to carry traffic. LOS is also a standard contained in the City’s General Plan. The City’s LOS standards are described based on a lettering system - LOS A through LOS F, with LOS A being the best. At LOS A drivers enjoy free flowing traffic conditions with individual drivers virtually unaffected by other vehicles on the street. LOS D is the heaviest congestion level allowed by the General Plan. At LOS D, high-density traffic flow restricts speed and the ability to maneuver although traffic flows remain constant. There is an exception to the General Plan standard for one City intersection located at El Toro Road and Avenida de la Carlota which is part of a county-wide traffic plan known as a Congestion Management Plan (CMP). CMP intersections may maintain a LOS E. It should be noted that Orange County refers to its CMP as the “Master Plan of Arterial Highways.”
The State also requires cities to consider “vehicle miles traveled” or “VMT.” This is related to greenhouse gas emissions (GHG) and is a component of State policies that require cities to address climate change when considering new development. The State’s environmental goal is to reduce VMT thereby reducing vehicle-related air emissions that contribute to climate change. Using public transit and carpooling reduce VMT and could also reduce traffic congestion.
For the approved 2016 Five Lagunas Project, a full traffic study was conducted which analyzed 61 intersections in and around the city for traffic impacts. When compared against traffic from mall operations, the Five Lagunas project was expected to result in an increase of only 6,434 additional vehicle trips per day. The increase was offset by the demolition of commercial building areas like Sears and the south half of the mall which housed retail uses. The addition of 988 multi-family units did not create significant traffic impacts since one (1) multi-family unit only generates about six (6) vehicle trips per day versus shopping centers, which generate about 43 vehicle trips per 1,000 square feet. The demolition of 1,000 square feet of retail could be replaced by seven (7) multi-family units and not result in a net increase in traffic. Traffic from the original operation of the mall was estimated at nearly 25,000 trips per day, even though actual traffic was lower.
Expected traffic from various land uses is based on surveys from the Institute of Traffic Engineers (ITE) which is a nationally recognized data source for traffic information (see FAQ 3). The traffic study for Five Lagunas determined that the project complied with the City’s General Plan traffic standards with some modifications to planned on-site traffic improvements. VMT was not studied in 2016 since there was no requirement to do so at the time. A new traffic study will be prepared for MGP’s new proposed project.
March 2021 Update: Also see FAQ 4 for a description of how anticipated traffic from the project will decrease by nearly 10,000 vehicles per day when compared to Five Lagunas.
Linscott, Law & Greenspan Traffic Impact Analysis for the Addendum to the City of Laguna Hills General Plan Program Environmental Impact Report for the Five Lagunas Project, Table 7, November 13, 2015.
Linscott, Law & Greenspan Traffic Impact Analysis for the Addendum to the City of Laguna Hills General Plan Program Environmental Impact Report for the Village at Laguna Hills Project, Table 6, September 1, 2020.