Underground parking is the optimum solution to the problem of a lack of parking in urban areas. It is discreet and ideal for large-scale parking, and also allows complete flexibility in the design of buildings and the disposition of uses and activity at ground level. The covering of underground parking provides a deck for development or landscaping, while surrounding buildings can face or back onto this space without constraint upon their configuration or aspect.

Viability is the biggest issues in developments using underground parking. Some sites lend themselves to underground parking more than others, either because of the value achievable for the completed property or because of site topography, where natural slopes can be used to reduce site excavation costs.

A variation on this arrangement is possible where the parking is not entirely underground.

The depth of excavation can be reduced by raising the ground-floor deck level above the surrounding site, though this arrangement will only be acceptable where the parking floor is entirely enclosed by perimeter buildings. The semi-basement directly under the buildings can be used for additional accommodation either as part of the main property, as part of a live-work unit or as a separate annexe or basement apartment. Short flights of steps or a ramp from the street to the raised ground-floor entrances of the buildings offer the opportunity to introduce some variety in the appearance of the street scene. This design can also enhance the privacy of activity within the ground floors but can limit the range of uses possible on the upper ground floor. It may therefore require alternative access arrangements for disabled, older or less mobile people.

Vehicular entrance ramps to underground parking must be located directly off a street and, while they should be designed to be as unobtrusive as possible, should be clearly identifiable to all users. They should have a maximum gradient of 1-in-7 and ideally incorporate under-slab heating to avoid ice in cold weather. All underground car parks must incorporate a lift to a ground-level entrance lobby. Security issues are paramount and underground car parking provision needs to consider the usual criteria for deterring crime.

As with other parking solutions, the provision and type of ground surfaces should be considered from the outset of any new development, and an approach taken that enables the development to strike an appropriate balance between meeting the needs of all users over its lifetime, without the need for adaptation in the future, and addressing the technical requirements and future maintenance of highways.

Consideration needs to be given to the colours, patterns and types of surface used for ground cover. A varied mix of colours can be confusing for people affected by certain health conditions, including dementia, where black and/or dark colours can be viewed as holes, trip hazards or barriers. On a related note, a variety of patterns can create the illusion that there is no clear route to follow, and result in disorientation and anxiety.

Consideration should also be given to the potential for conflict between the provision of tactile surfaces designed for the blind or partially sighted, and the implications of such surfaces on accessibility for less mobile people, who may be using wheelchairs, mobility scooters or walking aids.

Wherever possible, underground car parking should be designed to be naturally ventilated.

With both underground and under-deck parking, consideration needs to be accorded to potential flood risks. In areas at high risk of flooding, the use of underground parking should be restricted.