Responding to the Blackout: The New York City Department of Transportation's Great Challenge

Institute of Transportation Engineers. ITE Journal, Mar 2006 by Tipaldo, John, Galgano, Steven

ON AUGUST 14, 2003, NEW YORK CITY, ALONG WITH A LARGE PORTION OF THE EASTERN UNITED STATES, EXPERIENCED A MASSIVE POWER FAILURE CAUSED BY AN OVERLOADED GRID IN OHIO. NYCDOT FACED THE DIFFICULT TASK OF ENSURING THAT TRAFFIC SIGNAL OPERATIONS AND COORDINATION PLANS WERE IN FULL WORKING ORDER FOR THE MONDAY MORNING RUSH HOUR.

INTRODUCTION

In August 2003, approximately 11,300 signalized intersections were located within the limits of New York City, NY, USA. Because the blackout occurred on a Thursday afternoon and power was not fully restored by Saturday, the New York City Department of Transportation (NYCDOT) faced the difficult task of ensuring that traffic signal operations and coordination plans were in full working order for die Monday morning rush hour.

To accomplish this task, NYCDOT utilized all available resources. The sheer volume of traffic signal locations-as well as the varied types of traffic signal controllers deployed throughout the city and the different means of communications employed to control the signalspresented unique problems. This feature outlines these efforts.

BACKGROUND

In the late 1960s, as part of the TOPICS program, the agency began the lengthy implementation of a Vehicular Traffic Control System (VTCS) aimed at controlling approximately 6,000 of the 11,300 signalized intersections in New York City. The city's traffic signal network was broken into 15 segments. An area computer was designed to handle traffic signal operations for each segment.

Because electromechanical controllers were used, the system was designed so that signals would operate via the centralized computer with the operation constantly monitored by electricians located in the traffic management center (TMC). All but one of the area computers (Staten Island) are located in the agency's TMC in Long Island City, NY.

The Staten Island area computer is located within Staten Island and communicates directly with the central computer located in Long Island City via dedicated telephone lines. All 15 area computers are connected to a supervising computer, which oversees their continuous operation.

The VTCS allows the agency to operate time-of-day and day-of-week patterns along the equipped arteries. In addition, the VTCS allows monitoring of the second-by-second operation of any traffic signal on the network.

In addition to controlling all computerized intersections within New York City, the TMC is responsible for monitoring traffic conditions throughout the city via the agency's more than 150 traffic surveillance cameras. The New York State Department of Transportation (NYSDOT) and the New York Police Department (NYPD) also operate TMCs from the same facility in Long Island City. The different centers are adjacent to each other, with ongoing construction on a joint facility to house all three agencies.

The remaining 5,300 signalized inter sections within the city primarily were "stand alone" intersections with no active communication or control from the central VTCS systems. These intersections primarily were timed on fixed patterns that were in effect 24 hours per day.

The agency would become aware of problems at these intersections via public complaint or periodic inspection and, when made aware of a problem, would dispatch the maintenance contractor to make necessary repairs.

In August 2003, the TMC was able to monitor and control the operation of more than 50 percent of the entire traffic signal plant within the city. The means of communication to the traffic signals from the VTCS system varied by its location within the city. This only complicated the response to the blackout.

COMMUNICATIONS

Manhattan Signalized Intersections

In the 1980s, NYCDOT began an ambitious program to install agency owned, operated and maintained coaxial cable network within the borough of Manhattan, NY. This network was completed in 1995, allowing more than 2,700 signalized intersections within Manhattan to operate via the central computers located at the TMC.

When a traffic signal malfunctioned, the technician who monitored the system immediately dispatched the maintenance contractor to the location to determine the scope of the problem. If the problem was isolated within the controller itself, the maintenance contractor made the necessary repairs. If the problem was one of communications, the technician then dispatched in-house crews to repair the communications problem.

Outer Borough Signalized Intersections

In the 1980s, NYCDOT began to implement and operate computerized traffic signal arteries in the outer boroughs. The agency entered into an agreement with Verizon, and analog circuits were installed to connect the individual locations directly with the TMC through twisted pair lines. Communication was routed through the Verizon network and direct connections were made into the agency's central VTCS.

The agency paid a fixed amount per month for each circuit (based upon distance from the TMC). Verizon was responsible for the maintenance of the circuits. In August 2003, more than 3,300 intersections were under VTCS control in the outer boroughs.