Transportation Development District

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Mercer County’s TDD was the first to be approved in the state of New Jersey. It was developed in response to the development pressures in a relatively undeveloped area of the county. In late 1998, Mercer County initiated a comprehensive land use/transportation study designed to determine the appropriate development densities and infrastructure needs for the I-95/295 Corridor. This area of the county was under great development pressure and Mercer County officials sought to anticipate future development and provide a mechanism by which the necessary infrastructure improvements could be effectuated. The study process involved a cooperative effort between the county, municipalities and land owners. The resulting report, prepared by Wallace, Roberts and Todd et al. entitled Comprehensive Development Plan and Infrastructure Impact Analysis for the Mercer County I-95/295 Corridor (WRT Study) formed the basis for the Transportation Development District and its accompanying plan. The TDD Plan was approved by the New Jersey Department of Transportation in October of 1992 and in November of 1992, the Mercer County Board of Chosen Freeholders adopted Ordinance No. 92-17 to support its implementation.


The current version of the TDD uses 1990 as a base year and has a horizon year of 2010. It describes the present conditions (of 1990) and the future projections for the area. The overall goal of the TDD is to manage growth and coordinate and finance transportation infrastructure improvements in regional growth area.
The TDD is generally bounded by Pennington-Washington Crossing Road (Rt. 546) to the north, Federal City Road to the east, Upper Ferry Road to the south, and the western edge includes lots west of Scotch Road.
The TDD plan identifies transportation infrastructure improvements that will be needed within the District to support anticipated development. The transportation goals of the TDD are to maintain acceptable traffic flows, protect quality of life for existing residents and make alternatives to single occupancy auto more attractive. The plan describes in greater detail how these goals are achieved. It prioritizes the improvements and allocates a public and private sector share of the improvement costs. In addition, it established a trip based fee to be collected.

The Effect of Transportation Development District Designation

On April 2, 1990, New Jersey Department of Transportation (NJDOT) Commissioner Thomas Downs designated the I-95/295 Corridor in Hopewell, Ewing and Lawrence Townships as a Transportation Development District pursuant to NJSA 27:1C-1 et seq., June 26, 1989. This action sets the Development Assessment Liability date at April 2, 1990.
Under this law, counties in cooperation with NJDOT may establish Transportation Development Districts (TDD’s) to assess development fees for transportation improvements.

Any development receiving preliminary approval after the Development Assessment Liability date is subject to the fee. The fee must be "reasonably related to the added traffic growth attributable to the development..." The fee structure was determined through a Joint Planning Process which involved representatives of all levels of government and the private sector. This Joint Planning Process produced a Transportation Improvement Plan which identified needed transportation improvements, established a fee formula and identified public resources available. This plan was adopted by the Mercer County Board of Chosen Freeholders and approved by NJDOT. The county recently hired a consultant to update and revise the Plan. The Joint Planning Process Committee will be reconvened to assist in the effort. The update/revision is expected to take 18 months.

For further information, copies of the TDD plan, or for specific boundaries, please contact the Mercer County Planning Division 609/989-6545.