Soil amendments along roadsides were usually not practical, because of the high cost of amending these large planting areas. Seeding of native species have always been used with great success, but these types of roadsides are not always practical because of the potential for roadside fires when these areas become very dry. Then there is the ever-present issue of homeless encampments and security of adjacent properties prone to unmanaged wildscapes.

More recently, as the increasing cost of maintenance, water and a highway planting budget competing with highway safety projects (safety is always a higher priority), there was a need for Caltrans landscape architects to design affordable, attractive, context-sensitive roadsides with low water requirements and low maintenance requirements.

The slopes were sprayed with filtered fabric and gravel poured into the aluminum staked forms. The aluminum edging is used to separate areas and the filter fabric allows water filtration and abates weed.

The Interstate 5 and State Route 54 interchange in Southern California is traveled by millions every month, I-5 being one of the main freeways to Mexico, a few miles to the south, and SR 54 being a major arterial connector to I-805 to the east. This major interchange is adjacent to the Chula Vista Nature Center, which features interpretive displays featuring native plant and animal species of the adjacent Sweetwater Marsh Wildlife Refuge and the Pacific Coast ocean community.

This interchange was previously planted with salt-tolerant trees, shrubs and shrub ground covers. Still, this landscape died from the high soil salinity from the adjacent Sweetwater Marsh.

All rock material?EUR??,,????'?????<

In 2006, an alternate design?EUR??,,????'?????<

Faced with eroded slopes and unsightly bare areas, the design team, after considerable investigation, decided to use the concept of highway art to improve conditions. The highway art would provide a cover for inert materials, stabilize soil and slopes, while presenting attractive, decorative materials?EUR??,,????'?????<

Preliminary design concepts depicting different forms of coastal life such as white egrets, sea snails, shells, and star fish. These shapes were designed on a grid formed by squared meter units, first drawn to scale, then laid out on site.

The colored rock aggregates, 1/2 to 1.5 inch diameter, were dry spread approximately four inch in depth over a filter fabric weed barrier secured with metal stakes. A metal border with metal stakes were used to separate each of the colored rock shapes. (Don?EUR??,,????'?????<

With any luck, this highway planting should last 20 to 30 years with minimal touch-ups and almost no watering required, except for the islands.

Planting berms, created by excavating onsite soils, were installed on the top flat part of slopes, covered with plastic liners, then topped with imported soil. Palms were planted in the top soil of the berms with perforated plastic piping installed for drainage.