Chicago Transit Authority Deploys Wi-Fi Mesh Network for Mobile Maintenance Management of Train Yards with SD.I and Tropos Networks

Innovative Wi-Fi Network Increases Productivity, Shortens Maintenance Cycles and Improves Overall Customer Service

CHICAGO, Feb. 13 / / -- SD.I (System Development Integration, Inc.) and Tropos Networks, today announced the successful deployment of a sophisticated Wi-Fi mesh network in rail yards used by the Chicago Transit Authority (CTA), the second largest public transit system in the nation. The CTA installed the network to cover ten of its rail yards, with the largest storing up to 282 railcars. The system enables the CTA to move its rail yard maintenance inspector's transactions from paper to high speed Wi-Fi networks.

SD.I, a systems integrator specializing in fusing technical and operational support for capital asset intensive organizations, and Tropos, the market leader for metro-scale wireless mesh network systems, began this project in the first quarter of 2007. The CTA first conducted testing of the new wireless system in the ten yards and full implementation was completed in mid-Q2 2007.

Until this project, CTA rail car inspectors had conducted manual inspections of train cars in the rail yards, reporting defects, taking mileage readings and making repairs. As part of its system-wide Maintenance Management Information System (MMIS) initiative, the CTA decided to automate these maintenance procedures using hand-held computers and state-of-the-art Wi-Fi mesh networks in order to improve the quality and efficiency of train maintenance. The new process reduces the time from inspection to repair.

The CTA rail environment is extremely unfavorable for wireless communications because the metal rail cars typically reflect radio signals rather than allowing them to penetrate. This can lead to signal distortion and a reduction in overall throughput. SD.I chose Tropos' MetroMesh solution because it uniquely handles this issue in two ways. In field testing, the RF signals from Tropos routers were able to reliably penetrate eight CTA rail cars. This is attributable to Tropos' use of high quality radios that provide high power, sensitivity, and fidelity. In addition, Tropos' patented Predictive Wireless Routing Protocol (PWRP) intelligently routes the wireless signal, selecting the path that provides the highest throughput, routing around obstacles and thereby reducing data loss.

The implementation of the network provides the CTA's maintenance management systems' handheld devices with reliable connectivity. The CTA is now able to increase the speed of reporting details from the inspection of its rail vehicles, giving the maintenance managers real-time information of items requiring maintenance and easy access to detailed defect information first thing in the morning.

"The CTA recognized the need to design a solution that addressed its unique environment, yard by yard," said Brian Diver, executive vice president, SD.I. "Our experience with operations in non-traditional settings along with the performance and reliability of the Tropos mesh network, has resulted in a highly utilized and well-performing system."

Because defect descriptions are programmed in the handheld devices, information is now presented in a concise, consistent manner to each manager, making it easier to determine the maintenance status of all rail cars. CTA inspectors also scan each rail car number into the system before an inspection, improving the accuracy.

"Every day and around the world, our Tropos MetroMesh networks meet the rigorous communication and reliability demands for a range of enterprise applications, from public safety to utility meter reading to mining and port operations," said Tom Ayers, president and CEO of Tropos Networks. "We are pleased that our technology contributes towards improving the quality of CTA's maintenance programs and productivity of its mobile workers."

About CTA

The CTA operates the nation's second largest public transportation system and covers the City of Chicago and 40 surrounding suburbs. On an average weekday, 1.6 million rides are taken on the CTA. CTA has approximately 2,000 buses that operate over 154 routes and 2,273 route miles. Buses provide about 1 million passenger trips a day and serve more than 12,000 posted bus stops. CTA's 1,190 rapid transit cars operate over eight routes and 222 miles of track. CTA trains provide about 500,000 customer trips each day and serve 144 stations.

About SD.I

SD.I is a systems integrator that fuses information technology, security, operations and facility management to provide advisory services, technology delivery and SmartSourcing(SM) long-term support. With over 17 years of private and public sector experience, SD.I provides vendor-independent services and support to our nation's mission-critical environments to achieve a higher level of security, increase productivity and reduce operating costs. SD.I embodies the technical breadth, depth of talent, and complex systems experience of a national, top-tier systems integrator -- with a reputation of sticking with our projects until our obligations are met and our clients are successful. For more than 17 years, we've been there for our clients, and people are taking notice. Visit us at

About Tropos Networks, Inc.

Tropos(R) Networks is the market leader in delivering metro-scale wireless mesh network systems. The company's systems have been selected to unwire more major league cities than all competitors combined and are installed in 30 countries. The patented Tropos MetroMesh(TM) architecture delivers the ultimate scalability, high capacity at low cost and great user experience demanded by service providers, municipalities and network users. Tropos Networks' unique expertise includes high-performance mesh software development, mesh RF engineering, metro-scale network planning, deployment and optimization, and navigating the municipal approval process. Tropos Networks is headquartered in Sunnyvale, California. For more information, please visit, call 408-331-6800 or write to

Tropos and PWRP are registered trademarks of Tropos Networks, Inc., Tropos Networks, MetroMesh, MetroMesh NG, AMCE, TMCX, SABRE, CMDP, MESM and Metro-Scale Mesh Networking Defined are trademarks of Tropos Networks, Inc. All other brand or product names are trademarks or registered trademarks of their respective holder(s).

Source: SD.I

CONTACT: Scott Green of CLS Communications Inc., +1-650-679-9044,, for Tropos

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