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8.5.2 Baltimore Integrated Traffic Management System

System Description

The City of Baltimore Integrated Traffic Management System is a major upgrade of the City of Baltimore’s street traffic management system.  It involved replacement of all traffic signal controllers and cabinets, installation of additional closed circuit television cameras, upgrading and expansion of center-to-field communications infrastructure, video exchange with CHART, a new traffic management center, new central computer hardware and software for remote management of field devices, and updated traffic signal timings. 

The $26 million project provides Baltimore, Maryland, with a state-of-the-art traffic management system that provides many capabilities missing from the previous system. These new capabilities include:

  • NEMA TS2 functions added to all traffic signal controllers (replacement of 1970s era pre-NEMA controllers and cabinets, new signal timings, automatic fallback to controller-based time-of-day timing plan selection).
  • Support for additional traffic control strategies such as traffic responsive and traffic adaptive.
  • Integration of signal control along the Howard St light rail corridor provides support for light rail transit priority
  • Ability to choose future traffic signal controllers from multiple vendors (NTCIP standard communications protocol).
  • 300 additional traffic signals able to be remotely monitored and managed (new communications cable and modems, and upgraded communications hubs).
  • 100 intersections able to be visually monitored from the traffic management center (new CCTV cameras).
  • Numerous additional functions available to operators at the traffic management center (new TMC, new central software, new graphical user interface, asset management software).
  • Remote monitoring and management of field devices, including viewing of live video from CCTV cameras, available to more City personnel from more locations (link to City computer network, additional remote workstations, fiber optic cable between TMC and Signal Shop, web-browser-based access via the Internet).
  • Ability to view live video from freeway cameras owned by Maryland DOT, and ability to make City camera feeds available to State traffic management personnel (two-way inter-agency video exchange via fiber optic link to Maryland Stadium Authority and hence to Maryland CHART).
  • Ability to monitor vehicle flow and incident information along Maryland DOT freeways via a standalone CHART workstation located in the City of Baltimore TMC.

Together, these new capabilities enable more efficient and safer traffic signal operation, faster and more effective response to disruptive incidents, reduced system maintenance costs, and opportunities to further enhance traffic management in the future by measures such as automated traffic counting, traffic responsive signal timing plan selection, and adaptive traffic signal timing.

Involved Agencies and Their Roles

The City of Baltimore, via its Department of Transportation, was the system owner and dominant stakeholder.  The Maryland DOT (CHART) and Maryland Stadium Authority were involved by virtue of a two-way video and traffic data link between the new Baltimore traffic management system and existing Stadium Authority traffic operations centers at the M&T Ravens Stadium and Orioles Park at Camden Yards.  These operations centers had existing communication links to Maryland CHART thus also providing a path for video and traffic data exchange between CHART and the City traffic management system.   Inter-agency operational coordination was further enhanced by provision of a CHART workstation at the City traffic management center. 

The Federal Highway Administration played an important role in administering funds including timely approval of time-and-materials work orders.

Contractors and Their Roles and How Selected

The following table summarizes the various contracts used to implement the Baltimore Integrated Traffic Management System.


Contracting Party

Procurement Method

Contract Overseer

Program Management (including design)

City of Baltimore

Professional Services (RFP)

City of Baltimore DOT

Field Construction (including controller and cabinet installation)

City of Baltimore


Program Management Contractor

System Integration

City of Baltimore

Professional Services (Prequalification, RFP)

Program Management Contractor

TMC Architectural Design

City of Baltimore

Professional Services (RFP)

Program Management Contractor

TMC Construction

City of Baltimore


Program Management Contractor

Signal Timing Optimization

City of Baltimore

Professional Services (RFP)

City of Baltimore DOT

A feature of the City’s approach to contracting for this project is the degree of flexibility built into contracts.  In particular, the program management contract with Sabra, Wang & Associates allowed for refinement of tasks and addition of tasks in response to unforeseen conditions.  For example, project funding became available in multiple allocations, some at quite short notice, and the nature and extent of later-stage work was not fully known until after major components were selected during earlier stages.  The system integration contract allowed for some design-build elements and loosely-defined later tasks that were refined as conditions and needs became clearer during system development.  Such flexibility allowed a relatively large project to be implemented quickly and continuously with minimal administrative effort on the part of City personnel, while retaining the flexibility the City needed to adapt to evolving funding and technical conditions.


Agencies’ Previous Systems Engineering Experience and Capabilities

Involved City of Baltimore personnel had very little experience in projects like this and little prior experience with systems engineering.  The prior traffic signal management system was installed in 1976 and underwent only one significant upgrade, which replaced a mainframe computer with a minicomputer in 1994.  


Systems Engineering Management Planning

No formal systems engineering planning was conducted.  However, the program management and system integration contractors were familiar with systems engineering and used sound practices despite the lack of explicit planning.  Most of the major systems engineering processes were included and documented, as summarized in the attached table titled Summary of Systems Engineering Activities Undertaken in Development of the Baltimore Integrated Traffic Management System.


Comments on the Overall Experience

The Baltimore Integrated Traffic Management System project is successful and is achieving its goals. 

Although the City did not plan for or require use of the formal systems engineering process, the contractors involved were accustomed to using systems engineering and knew it was necessary for a successful project.  The contractors used the systems engineering process. 

Use of the NTCIP communications standard for traffic signals was key to the project’s success.  The central signal management software and traffic signal controllers are from different manufacturers and had not been previously integrated.  Integration went relatively smoothly largely because both the central software and the controllers supported the NTCIP communications standard for traffic signals.  The integration effort revealed some inconsistencies in the respective implementations of NTCIP, but these were easily corrected.  The City now is able to procure controllers from multiple NTCIP-compliant manufacturers.  If the City wishes to use features not directly supported by the NTCIP standard, the standard provides a convenient mechanism for adding manufacturer-specific objects or data elements to any message, including the once-per-second status message.  Due to its low bandwidth overhead, NTCIP’s “dynamic objects” feature allowed re-use of the existing City-owned twisted wire pair cable network.

The project was not without its surprises and challenges.  The following are some examples:

  • It took six months to reach a resolution and agreement on the licensing rights between the system integrator and the local controller vendor. Many of the required MIBs in the local controller software are proprietary, and the vendor requested non-competing and copyright provisions prior to releasing the MIBs for the central system integration.
  • The central software integrator had to perform regression testing against eleven different versions of the controller software. 
  • The 20-30 year old twisted wire pair cable was found to be deteriorated in several segments and problems became more apparent when the new high-speed modems were first used during the cutover process (broken pairs, noise voltage on the line, old/brittle insulation, crossed-pairs, use of non-twisted pairs, etc.).  The controller replacement contract did not include replacement of the communication cables and therefore it was not clear as to which party was responsible for correcting each type of problem.  This problem was later corrected by adding an ancillary Change Order to replace all communication hubs and malfunctioning cables.
  • Not all involved personnel had adequate training or experience in use of communications test procedures and tools, and circuits were sometimes mistakenly reported as operational. 
  • Communications circuits that were adequate for the old system were sometimes not adequate for the new system due to the different characteristics of the old and new modems.
  • The City desired a one-time program management contract and system integration contract, but could not accurately predict the full scope of work needed for these at the outset – things changed unexpectedly and some scope-affecting decisions had to be made during the project. 
  • After a contractor’s submittal had been approved and in the process of implementation, an individual in an involved agency became aware of the work for the first time and identify a needed, or at least desired, change.
  • The communications modem supplier made a minor version change that was assured to be inconsequential and it was not discovered until after many units were in the field that it was causing a subtle but intolerable problem.
  • Transition from the old system to the new system was done on a channel by channel basis and involved intersections from different streets, thus making signal timing coordination during construction very challenging to maintain. Signal timing plans, using a time-of-day time-based-coordination mode, were developed and tested ahead of time to deal with this challenge.
  • In accordance with the contract requirements, the contractor was required to replace a minimum of 6 controllers per day and work at multiple intersections simultaneously.  On some days, 10 controllers were actually replaced and three crews worked simultaneously. This activity required at least six police officers to control traffic during the change over.  Needless to say, all controllers that were replaced had to be cutover in the central system on the same day so that real-time monitoring and communications could be maintained.
  • This project was very labor intensive and required continuous motivation and forward thinking.  Bi-weekly meetings over a three-year period were held with every responsible agency and contractor.  There were too many issues as expected, however, they were always resolved mutually, and the contractor was always complemented for his hard work.  The City also provided on-site inspection and engineering support to assist the contractor in concerns that were thought to be out of his scope.  This, for example, including trouble shooting communication lines, correcting old splices, and draining water from manholes, etc.

On the other hand, many aspects of the project proceeded very smoothly.  The following are a few examples:

  • The project progressed largely as planned due to use of systems engineering techniques including initial preparation of a concept of operations, clear statement of requirements, requirements-driven design, a comprehensive testing plan, and sound configuration documentation.
  • Thorough bench testing of field equipment including use of a realistic group of signal controllers and actual cabinets worked very well and with one exception (the above-mentioned modem issue), found problems prior to field deployment.
  • Frequent incremental testing during system integration and involvement of City personnel in those tests helped build and maintain confidence on the part of all parties and enabled 
  • Use of the NTCIP communications standard facilitated controller integration as discussed above.
  • Good status and configuration documentation (e.g., hardware and software state, activities log, problem tracker, etc.) made it easy to measure progress, make changes when needed, and stay focused on outstanding problems. 
  • A well planned and methodical approach to cutover of communication circuits from old to new controllers helped that process proceed efficiently.
  • An experienced program management consultant helped greatly in keeping the project on track and dealing with unexpected problems as they arose.
  • The project was completed on-time and under budget.

The Key Lessons Learned from the Baltimore Integrated TMS Project

Use of an experienced program manager and the systems engineering process enabled a complex project to be successful.

Flexible contracts with the program manager and system integrator enabled the contracts to be changed midstream to accommodate unforeseen or changed conditions.

Use of the NTCIP communications standard was key to enabling integration of central software and field equipment from different manufacturers, and in giving the City the option to purchase future field equipment from different manufacturers.

Thorough and realistic testing at every stage of system implementation, involving the owning agency in testing, and testing every change no matter how small and seemingly inconsequential, helps with progress monitoring and avoids expensive and time consuming field retrofits. 

Contractor submittals should include a signatures page that all concerned personnel must sign before work can proceed.  This ensures the document has been reviewed and approved by all interested parties. 

Use of old equipment can lead to unforeseen problems that need to be accommodated.  Facilities that work fine with an existing system may not be adequate for the new system with its different characteristics.

Contracts should clearly delineate boundaries of responsibilities between the involved parties.

Adequate training of all involved personnel is important, especially when new technology is being used or existing technology is being used in a new way.

A carefully planned and methodical cut-over plan can add to the efficiency of changing over from old to new equipment.


Ziad Sabra, Principal of Sabra, Wang & Associates, generously contributed his time for interviews, and contributed much of the information collected for this case study. Sabra, Wang & Associates is the program manager.

Table 8‑2 Summary - Baltimore Integrated TMS Systems Engineering Activities by project phase

Process Task

Process Used

Documents Produced

Agency Effort


Explanation, Issues, Problems, Lessons Learned


No formal feasibility study.


Informal notes and meeting minutes only.





Technical memoranda discussed controller options, architecture options, and communications options. Meetings were held with CHART and Stadium Authority to determine the needed linkages between the systems, but no formal documentation.


Various technical memoranda.



Program Management contractor helped the City with system planning. Time and materials contract with task orders was critical to allowing contractor work to vary as needs were identified.

Concept of Operations

Concept of operations documented at start of design.

Concept of Operations


Helped by fact that the City already operated a traffic signal management system.

Validation Plan

Planned to conduct travel time surveys before and after system implementation.

Plan not formally documented.


Included before-and-after studies.

System Requirements

Identified during high level design.

Documented within procurement specifications.


Program management contractor worked with City personnel to identify requirements. Prescriptive (specifications) for most field hardware, but kept as functional requirements where possible.

System Verification Plan

Developed at start of system design.

Documented in the system integration services contract.



High Level Design
Sub-system Requirements and Verification Plans

Part of design.

Documented within procurement specifications – functional specs.



Component Level Design

Done by system integration contractor.

Hardware Selection, Software Design, System Configuration, Graphics Design



Hardware and Software Development

Off-the-shelf hardware and software, with some central software enhancements.

Updates of above documents to reflect “as built”.


NTCIP very helpful in integrating field devices with central software.

Unit Verification

Individual pieces of field equipment were inspected by Program Manager upon installation. Controller software was bench tested by the System Integrator. Computer hardware units were tested by the System Integrator. Controllers and modems tested prior to installation.

Inspection and test reports.


City personnel involved in review and testing of new signal controllers and cabinets.

Unit Integration

Performed by the System Integrator.

First draft of system configuration documents.



Sub-system Verification

Sub-systems were center-to-field communications, traffic signals, CCTV, DMS, TMC display equipment.

Test reports.


Central software replicated with number of field equipment units for system integrator bench testing at the Signal Shop. Used for acceptance testing too. City personnel involved in review and testing of communications sub-system.

Sub-system Integration

Performed by the System Integrator.

Updated system configuration documents.


Groups of signals were brought on line one at a time and tested individually.

System Verification

Final integrated system acceptance testing performed by the system integrator and witnessed by the program manager and the system owner.

Acceptance Tests




Cutover to the new system progressed one communications circuit at a time.

Implementation Plan




Before and after study using travel time surveys.

Before and After Travel Time Survey



Operations and  Maintenance

TMC staffing needs were identified.

TMC Staffing Plan



Changes and Upgrades

Some future system enhancements have been anticipated and allowed for in system design.





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