Why Are Sidewalks Raised Up: A Comprehensive Guide

In urban areas, you've likely noticed that sidewalks are often raised several inches or as much as a foot above the street. This height difference serves several practical purposes, including preventing water from flowing onto the walking surface and ensuring pedestrian safety. In this article, we'll delve into the reasons behind elevated sidewalks, explore the importance of proper drainage, and examine how curb design has evolved over time.

The Basic Principle: Drainage

Streets are typically designed with a crown in the center to channel water towards the sides, away from the pedestrian areas. If sidewalks were not raised, the water would run over them, potentially flooding the walking path and posing a safety hazard. This crown pattern is further augmented by drains, which are usually positioned beneath the sidewalks to manage the flow of water.

When it rains, the river of water needs to stay off the sidewalks as much as possible. The street slopes towards the sidewalks to direct water away from the pedestrian area, and the height of the sidewalk serves as a barrier to keep this water and any associated trash away from where people walk. Proper drainage is crucial to maintaining clean and dry walking surfaces.

Historical Reasons for Elevated Sidewalks

Initially, curbs were installed to prevent carriages from running off the road. The term "curb" also refers to the edge of a sidewalk that blocks vehicular traffic, ensuring a separation between road and pedestrian zones. In areas with violent rainstorms, streets and curbs form a natural channel that drains storm runoff efficiently.

One of the primary reasons for elevating sidewalks is to prevent water from flowing into buildings. If sidewalks were at the same level as the street, the entrances to stores, houses, and other buildings would also be at street level. During heavy rain, everything would quickly flood, creating a hazardous environment for pedestrians.

Secondary Benefits and Safety Considerations

Several benefits contribute to the elevating of sidewalks, not the least of which is pedestrian safety. A higher sidewalk allows rainwater to quickly drain into the storm sewers, reducing the risk of flooding in buildings and ensuring that the walking path remains dry. At one foot high, the increased elevation also makes it more difficult for cars to jump the curb and cause accidents.

In addition to preventing flooding, raising the sidewalks keeps long skirts out of horse manure. This concern, though less relevant today, highlights an historical imperative to maintain cleanliness and hygiene on walking surfaces.

The Evolution of Curb Design

Curb design has evolved to address the needs of modern urban life. The primary goal remains the same: to create a safe and efficient separation between pedestrian and vehicular traffic. Modern curbs are often more precisely engineered to manage water runoff and to provide a clear boundary between the sidewalk and the street.

Efforts are also made to balance accessibility and safety. For instance, tactile pavers and other features are sometimes added to curb lines to assist visually impaired pedestrians. Moreover, curbs are designed with a slight slope to direct water away from building entrances, further reducing the risk of flooding.

Conclusion

In conclusion, the elevation of sidewalks serves multiple important functions, including efficient drainage, safety, and the preservation of historical design principles. Understanding these reasons can help us appreciate the thoughtful planning that goes into urban infrastructure and the importance of maintaining safe and accessible pedestrian environments.