Ramp slopes are an integral component of parking garage design, impacting safety and accessibility as well as raising construction costs.
When designing a ramp, the slope must be calculated based on the height of the building. As height increases, the slope must increase by an approximate 5%-6% per foot.
Ramps come in many forms, from curved to straight and helical. These can be one-way or two-way traffic.
Clearway ramp systems offer safe, swift movement with little delay - ideal for self-park designs. However, this type of system may prove challenging to design for small garage sites or structures situated on hillsides.
Some structures, such as airports, casinos and large retail outlets, utilize non-parking ramps. Common designs include circular helixes (the most common), express ramps and speed ramps.
Ramps can range in length from 100 feet to 290 feet, depending on the design requirements. The slope should not exceed 12%-14%.
In some instances, ramps can be made wider to accommodate vehicles that use the left side of their vehicle. They may also be interwoven to reduce 360-degree turns.
Ramps are typically found in tall buildings and should not be utilized on lower floors as it could restrict access to the upper levels.
Parking-on ramps are the most efficient of all ramps when their floor-to-floor height falls between 5-6 percent. Unfortunately, if this height exceeds 6.5 feet or more, these ramps won't work since they lack sufficient length to be effective.
When a standard parked-on ramp cannot be built, an express or speed ramp may be installed to serve the different levels of a garage. These are generally shorter in length than their counterparts and usually feature transition slopes at both the top and bottom to prevent vehicles from "bottoming out."
To calculate the grade of a parking ramp, multiply its floor-to-floor height by 100 and divide that result by its total length.
When designing a straight ramp, the minimum width should be 3 meters for one-way traffic and 4.5 meters for two-way use. Curved ramps need at least 7 meters in width for one way traffic and 8.25 meters when accommodating both directions of travel.
Many times, the location of a new parking garage is hilly. This can reduce the internal ramping necessary to achieve desired garage dimensions and result in lower costs overall.
When planning a parking garage on an uneven slope, it is wise to conduct a site survey in order to understand the soils and geology of the property. This will reduce ramp requirements inside of the structure while also controlling visual massing.
