In 2003, the Average Daily Traffic (ADT) along I-93 ranged from 77,000 vehicles per day north of Exit 5 in Manchester to 114,000 vehicles per day south of Exit 1 in Salem. In addition to the high ADT, traffic incidents have occurred regularly on the stretch of I-93 from Salem to Manchester. The incidents vary in severity, from debris on the Interstate to overturned tractor-trailers, which cause motorists to seek detours on local streets, spreading congestion onto the parallel roads. It has become evident that a corridor-wide traffic incident management solution has become increasingly critical to keep people and goods moving. As a result, NHDOT in cooperation with the Federal Highway Administration (FHWA) and regional stakeholders, has sponsored the development of the Interstate 93 Corridor Traffic Incident Management Plan (I-93 TIMP).
The overall vision of the I-93 TIMP is the seamless management of traffic and emergency operations across multiple jurisdictional and agency boundaries for the I-93 Corridor from the Massachusetts State Line to the I-93/I-293 Interchange. This section of I-93 runs through the municipalities of Salem, Windham, Derry, Londonderry, and Manchester. In general, the I-93 TIMP promotes cooperation, coordination, information sharing and the application technology-based solutions, such as the use of dynamic message signs (DMS) to disseminate traffic information to motorists, and traffic signal coordination to increase throughput on alternate routes during incidents along the I-93 corridor. By improving the exchange of information among agencies, the NHDOT, New Hampshire Emergency Communication Section (NHECS), Emergency Responders and local municipalities can react more effectively to incidents on I-93, and minimize and manage the impact to local streets and services.
Development of this Plan has included an examination of the primary and secondary parallel alternate routes to I-93, identification of cooperative strategies and technologies that would aid in alleviating congestion, and recommendations for operations and maintenance roles and responsibilities. The I-93 TIMP is the beginning of a multi-stage program for improved traffic incident management, which includes the proposed Transportation Management Center and I-93 Intelligent Transportation Systems (ITS) deployment. In addition to the I-93 TIMP already developed, NHDOT is currently looking at ITS Systems and Incident Management Plans that will be developed specifically for the I-93 project corridor during the six year construction project. With proper guidance and funding, the I93 TIMP will evolve into a formal and sustained traffic incident management program.