Like any American city, the traffic signals in Baltimore, Maryland turn green, yellow, and red. A peek behind the curtain, however, unveils a defunct 1970s copper-based communication system and outdated ATMS software incompatible with current computer operating systems. Some effects are obvious like traffic delays and community complaints—others present new challenges to the city, such as achieving the newly adopted Complete Streets policy. Baltimore isn’t alone. Many American cities suffer the same “bubble gum and duct tape” reality in their traffic signal systems. This city, however, has a comeback story thanks to traffic engineering expertise and a committed partnership between the city and Mead & Hunt.
Challenges: In-person monitoring, clock drift, and mixed technology
The defunct communications system did not allow for remote monitoring and management. The controller clock for each signal suffers from “drift”—a term describing the signal’s internal clock running fast or slow. The erratic drift means the signals are not timed, resulting in delays and inconsistencies in traffic flow. Compounding this issue, field technicians must travel to each signal to fix problems such as clock drift, which takes quite a bit of time.
The city has implemented modernizing solutions to support multimodal efforts. The local transit agency, Maryland Transit Administration (MTA), funded a Transit Signal Priority (TSP) project which updated equipment at 269 of the city’s 1,369 signals. While helpful, the project has added complexity for the field technicians, already limited in staff, who are trying to overcome a learning curve of how to manage the old and new technology concurrently.
Partnering for an affordable, turnkey signal operation solution
To address the remaining 1,100 signals, the city chose to outsource its traffic signal operations project to Mead & Hunt as its first step toward a more comprehensive solution. Partnering with the city, Mead & Hunt accommodated the limited capital budget by utilizing technology to reduce the labor effort.
Engineers identified mini ATMS with rental cellular communications as a budget-friendly solution. Easily deployable, the device allows staff to remotely manage and monitor capabilities such as synchronizing clocks to eliminate drift. The implementation alleviates staff constraints as field technicians no longer must physically travel to each signal cabinet.
Mead & Hunt used institutional data and historical knowledge in field traffic operations to save on cost. Traffic counts were limited to major intersections, and model calibration was performed as part of field fine-tuning. Leveraging extensive previous experience, Mead & Hunt developed accurate models without spending money on extensive data collection. Partnering with the city, Mead & Hunt engineers applied their expertise to make well-informed updates to the system.
Mead & Hunt delivered Baltimore City an affordable, turnkey signal operation system through innovation and experienced discernment. The city successfully addressed citizen concerns as well as the elements of its Complete Streets policy, bringing its community into the 21st century.
