10.1.1 Block Dimensions
A new block, or an existing block where a change in dimensions is proposed, must have a length and perimeter in accordance with Table 10A: Block Dimensions, measured as follows:
- Block perimeter is measured along right-of- way lines along the aggregate of all block side lengths.
- Block length is measured along the right-of-way line of one block side.
- Where multiple zones apply to one block, the predominant zone along each block face will determine the maximum block length, and the least restrictive zone will determine the maximum block perimeter.
- Block dimensions may be calculated at a reduced length or perimeter where a mid-block passage connecting two block sides is installed as a dedicated right-of-way or reserved with a permanent access easement.
10.1.2 Block Features
- Block Shape. The shape of a new block must be generally rectangular, trapezoidal, or triangular, but may vary to conform to natural features, highway and rail rights-of-way, or park boundaries, or to provide interest and variety for pedestrians. Where blocks curve, they must generally maintain their cardinal orientation over their entire trajectory.
- Block Connectivity
- New vehicular rights-of-way must connect to and extend the existing block network where possible. This requirement does not apply to portions of the project boundary where connections cannot be made because of physical obstacles, such as prior platting of property, existing structures or other barriers, steep slopes (slopes over 15%), wetlands and water bodies, railroad and utility rights- of-way, existing highway rights-of-way, and parks and dedicated open space.
- All vehicular rights-of-way must terminate at other vehicular rights-of-way, forming a network. The Commissioner of Public Works, Parks, and Streets may grant an exception for culs-de-sac and dead-end streets in the following instances:
- No connection is available to an existing adjacent subdivision, or a natural or man-made barrier, such as a waterway, railroad, limited-access expressway, or unusual topography, exists that prevents connection.
- The cul-de-sac or dead-end street is no more than 330 feet in length, as measured along the centerline from the closest intersection.
- A pedestrian or bicycle through- connection is provided, if possible, from the terminus of the cul-de-sac or dead- end street to adjacent rights-of-way.
- Where adjoining areas are not developed, vehicular rights-of-way in new subdivisions must be extended to the project boundary line to make provision for the future projection of vehicular rights-of-way into the adjoining areas. Such rights-of-way must be provided at intervals no greater than the maximum block length for the zone, as indicated in Table 10A.
- Alleys may be required for new or reconfigured blocks. In all cases, blocks with existing alley access must maintain such access.
- A mid-block passage, dedicated as a right- of-way or reserved with a permanent access easement, may be required where a block side is longer than 660 feet. If required, the mid-block passage must generally be located in the middle third of the block side. When combined with mid-block crossings, these passages must align to facilitate easy pedestrian movements.
- Block Restoration. Where a block network has been disconnected due to urban renewal or other factors, the historic rights-of-way should be restored to the maximum extent practicable during redevelopment.
10.1.3 Waivers and Modifications
The Commissioner of Public Works, Parks, and Streets may waive or adjust the requirements of this section where the standards are determined to not adequately protect the public health, safety, and welfare.