Oversight of Selected Aspects of Traffic Controls

Issued Date
September 30, 2020
New York City Department of Transportation


To determine whether the New York City Department of Transportation (Department) is monitoring and evaluating traffic flow at intersections and whether the Department took action to improve safe traffic and pedestrian flow at intersections. The audit covers January 1, 2016 to March 13, 2020.

About the Program

The Department is responsible for providing safe and efficient movement of pedestrians, goods, and vehicular traffic on the streets, highways, bridges, and waterways of New York City’s transportation network.

The Signals & Street Lighting unit is part of the Traffic Operations Division (Division), and comprises, among other units, the Intersection Control Unit (ICU), responsible for conducting traffic control studies at intersections without traffic signals. The federal Manual on Uniform Traffic Control Devices (MUTCD) contains standards and recommended guidance for traffic control devices, including the need for studies and factors for justifying the installation of traffic signals and multi-way stop controls. Studies that result in denials may be referred to another Department unit for additional safety measures to be considered.

The ICU also evaluates the condition of existing traffic controls (e.g., pavement markings, signs) at intersections and notes necessary improvements that are referred to other units for review. Contractors are required to install approved traffic signals within 45 days of receiving the work order. The Division also initiates reviews referred to as proactive studies where it determines there is a need to evaluate an intersection. The Enhanced Intersection Unit (EIU) is one of the groups that receive referrals and is responsible for reexamining safety measures at intersections such as additional signage markings and improvements.

The Traffic Management Center (TMC), also part of the Division, operates 24/7 and is responsible for citywide traffic management, incident response, traffic signal operation and maintenance, and information dissemination. The Department coordinates incident response with its Office of Emergency Response, the New York City Police Department, and the New York State Department of Transportation, in the Joint Transportation Management Center. Midtown in Motion, a congestion management system used by the TMC, is used to improve traffic conditions in midtown Manhattan by identifying traffic issues and automatically adjusting signal patterns to smooth traffic flow.

Key Findings

The Department monitored traffic flow at intersections, but did not address the concerns of its customers in a timely manner. We reviewed several units that were supposed to perform monitoring and operational tasks and found that all of them need to improve their performance. Specifically, we found the following:

  • Our review of 78 intersection studies found it took the ICU an average of ten months (41 weeks) to complete a study, well beyond the four-month time frame specified in the Department’s Resource Guide. In fact, 34 studies took more than one year to complete.
  • We visited 17 intersections where the ICU recommended improvements and found six improvements that were not implemented and no evidence of the decisions made regarding the recommended improvements.
  • The Department did not provide any documentation that the EIU took action to determine if safety measures should be implemented at 5 of the 25 sampled locations based on proactive studies sent by the ICU.
  • The ICU did not maintain adequate support for the results of 10 of the 25 proactive studies reviewed. For example, four of the five signal approvals that were based on a warrant1 requiring automated eight-hour traffic counts did not contain the traffic counts or an explanation why the eight-hour counts were not conducted.
  • The TMC did not always monitor traffic conditions due to traffic cameras that were pending repair for significant amounts of time, including 35 traffic cameras that were out of service for over 180 days, with two traffic cameras out of service for over five years.

Key Recommendations

  • Revise the Department’s Resource Guide to make meeting the time frames a requirement.
  • Develop a process for the ICU to ensure that improvements recommended by its inspectors are implemented promptly. Document the reasons recommendations were not implemented or were modified.
  • Ensure the EIU reviews cases from the ICU and documents the results regarding any safety improvements that can be made to an intersection.
  • Ensure that intersection study files contain all required documentation, including, but not limited to, information supporting the conclusions in accordance with the MUTCD.
  • Develop procedures regarding the camera repair process and update the Electrical Shop Standard Operating Procedures.

1. Justification includes meeting at least one of the threshold conditions (warrants) that, if found to be satisfied as part of an engineering study, shall result in analysis of other traffic conditions or factors to determine whether a traffic control device or other improvement is justified.

Carmen Maldonado

State Government Accountability Contact Information:
Audit Director: Carmen Maldonado
Phone: (212) 417-5200; Email: [email protected]
Address: Office of the State Comptroller; Division of State Government Accountability; 110 State Street, 11th Floor; Albany, NY 12236