Road verge

A road verge is a strip of groundcover consisting of grass or garden plants, and sometimes also shrubs and trees, located between a roadway and a sidewalk. Verges are known by dozens of other names such as grass strip, nature strip, curb strip, or park strip, the usage of which is often quite regional.

Road verges are often considered public property, with maintenance usually being a municipal responsibility. Some local authorities, however, require abutting property owners to help maintain (e.g. watering, mowing, edging, trimming/pruning and weeding) their respective verge areas, as well as clean the adjunct footpaths and gutters, as a form of community work.

Benefits of having road verges include visual aesthetics, increased safety and comfort of sidewalk users, protection from spray from passing vehicles, and a space for benches, bus shelters, street lights, and other public amenities. Verges are also often part of sustainability for water conservation or the management of urban runoff and water pollution and can provide useful wildlife habitat. Snow that has been ploughed off the street in colder climates often is stored in the area of the verge by default.

In the British Isles, road verges serve as important habitats for a range of plants, including rare wildflowers. In the UK, around 700 different species of wildflower can be found growing on verges, including 29 of the country's 52 species of orchid. Verges can also support a wide range of animals and plants that may have been displaced from their usual grassland habitats, as the soil is not extensively fertilised and relatively undisturbed by human activity. Animals that reside on verges range from small insects and amphibians, to larger reptiles, mammals and birds, which rely on verges as a corridor connecting areas of undamaged habitat. As a result, verges may be managed by local areas to encourage biodiversity and conserve the ecosystems that rely on them.

The main disadvantage of a road verge is that the right-of-way must be wider, increasing the cost of the road. In some localities, a wider verge offers opportunity for later road widening, should the traffic usage of a road demand this. For this reason, footpaths are usually sited a significant distance from the curb.

Certain nutrient amounts in a verge's soil can be influenced by the amount of traffic on the road it sits beside; roads with heavier traffic tend to have more nitrate in the soil due to nitrogen compounds from air pollution leaching out of the atmosphere and into the ground.

In urban and suburban areas, urban runoff from private and civic properties can be guided by grading and bioswales for rainwater harvesting collection and bioretention within the "tree-lawn" – parkway zone in rain gardens. This is done for reducing runoff of rain and domestic water: for their carrying waterborne pollution off-site into storm drains and sewer systems; and for the groundwater recharge of aquifers.

In some cities, such as Santa Monica, California, city code mandates specify:

For Santa Monica, another reason for this use of "tree-lawns" is to reduce current beach and Santa Monica Bay ocean pollution that is measurably higher at city outfalls. New construction and remodeling projects needing building permits require that landscape design submittals include garden design plans showing the means of compliance.

In some cities and counties, such as Portland, Oregon, street and highway departments are regrading and planting rain gardens in road verges to reduce boulevard and highway runoff. This practice can be useful in areas with either independent Storm sewers or combined storm and sanitary sewers, reducing the frequency of pollution, treatment costs, and released overflows of untreated sewage into rivers and oceans during rainstorms.

In some countries, the road verge can be a corridor of vegetation that remains after adjacent land has been cleared. Considerable effort in supporting conservation of the remnant vegetation is prevalent in Australia, where significant tracts of land are managed as part of the roadside conservation strategies by government agencies.

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  Ginkgo street trees in the "boulevard" area, in Riverside, Illinois
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  A planted garden in the "tree lawn", in Raleigh, North Carolina
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  A "parkway" with street trees in Oak Park, Illinois
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  A tree lawn with street trees in Shaker Heights, Ohio
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  A tree lawn with street trees in Shaker Heights, Ohio

The term verge has many synonyms and dialectal differences. Some dialects and idiolects lack a specific term for this area, instead using a circumlocution.

Terms used include:

• Parkway with xeric garden photographs
• Devil Strips – term's use and lore