Whats New at SWA!

BaltimoreLINK Transit Signal Priority 5.2017

Sabra & Associates, Inc. (SAI) is leading the planning, design and implementation of Transit Signal Priority (TSP) as part of BaltimoreLink, the Maryland Transit Administration’s (MTA) complete overhaul of the entire bus system to improve the speed, efficiency and reliability of transit in Baltimore City.   TSP will be a feature on twelve, high-frequency, radial, bus routes called CityLink, and will ultimately operate at approximately 200 signalized intersections.  TSP launches on 36 intersections along the Red and Green CityLink routes next month – starting on June 18, 2017.


For a map of the new system, click here

TSP modifies normal traffic signal operations in real-time to provide special treatment to transit vehicles without disrupting the coordination operations of the traffic signal system.  BaltimoreLink TSP will be an “active” system, meaning that the specialized equipment are deployed on the bus and at the traffic signal to predict the arrival time of the bus, and either hold the green time longer (green extension) to allow a bus to “make-it” through the intersection, or reduce the red time (red truncation) so the bus does not have to wait as long.


MTA uses TSP at 16 intersections along the Howard Street Light Rail Transit Corridor; the BaltimoreLink TSP system will be an expansion of this system. SWA recently upgraded the TSP system on Howard Street, resulting in a reduction of nearly 180 person-hours per day, a reduction LRT travel times by 8%, and decreased the chance of stopping at a traffic signal by nearly 40%.


Click here for an overview of the TSP system on Howard Street


The TSP planning phase consisted of the analysis and selection of where to deploy TSP, and the physical and computer systems necessary to make it work.   Extensive traffic and transit analyses of all 700 traffic signals on CityLINK bus routes was conducted to determine which traffic signals, when equipped with TSP would potentially provide the most benefit to CityLINK buses traveling along the corridors. The two initial corridors (CityLink Red and Green) were selected based on high bus ridership, flexibility within the traffic signal timings to accommodate TSP.  The current traffic signals on the Red and Green corridors did not provide Transit Signal Priority algorithms in the firmware (the resident software on the physical traffic signal controller), were not equipped with TSP equipment to communicate with the bus, and were not managed by a central traffic signal computer system.  As part of the planning process, SWA evaluated various TSP equipment, traffic signal controllers, centralized traffic signal software systems, and communications systems were evaluated.  Ultimately, the Global Traffic Technologies/ Opticom GPS system for TSP, the Trafficware ATC traffic signal controller and ATMS.Now centralized traffic signal system, and a Verizon cellular network were selected.

SWA prepared the intersection and electrical design plans to deploy the TSP equipment on the two initial corridors, which was completed by MTA’s contractor, Mona-Gill Electric Group, Inc. in April 2017.  SWA also set-up and configured the ATMS.Now central traffic signal system;  tested, programmed and performed the field swap-out of 47 new ATC traffic signal controllers on the two corridors; and set-up the programming for the intersection Opticom TSP equipment at the 36 TSP-equipped intersections for a turn-key, fully-operational signal system that accommodates TSP.  The full system will be up and running by the end of May 2017, allowing SWA to remotely monitor and manage TSP, traffic signal timings and operations.


SWA will implement the TSP traffic signal timings in early-June, once the MTA completes the relocation of 13 bus stops from the near-side to the far-side of the intersection to improve the efficiency of TSP.  SWA will fine-tune TSP system operations throughout June and early July.


Planning work on the next CityLink corridors is underway and additional TSP deployments are planned in early 2018.

We have relocated our Northern Virginia Office to Tysons Corner in Vienna Virginia 4.2017

Our Northern Virginia Office has moved from Falls Church to Tysons Corner, in the Vienna area. The new office is conveniently located between the Tysons Corner and Greensboro Stations on the Metro Silver line.


Please be sure to update our new office location in your contacts to:

Sabra & Associates, Inc.

8150 Leesburg Pike, Suite 630

Vienna, VA 22182


Boston Street Multimodal Corridor Study 11.2016

SWA introduced the Boston Street study to the community at a public meeting in November to gain their understanding of the operations and needs of the corridor from those that live, work, and travel there daily. The study will provide recommendations to BCDOT that address improving truck access, accommodations for pedestrian and bicycle, travel for residents as well as commuters travel, and safety along the corridor.


7055 Samuel Morse Dr., Ste. 100
Columbia, MD 21046
443-741-3500 | F: 443-741-3700

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Transit Signal Priority