BE Magazine Volume 5, Issue 2 - (Page 30) CIVIL 12 four-car units. But when preliminary design started, that requirement had increased to 20 units, and included light maintenance and heavy cleaning facilities. Further project enhancements required Mott MacDonald to include a heavy maintenance facility for four train units, and a wheel-lathe and heavy-cleaning building as well. Bentley solutions enabled the team to make these changes quickly, and helped guide design decisions. The signal sighting process highlighted a critical flaw in the operability of the storage facility, which the Mott MacDonald team resolved quickly and efficiently. “The use of Bentley software in the signal sighting activity has enabled the project team to significantly reduce any chance that the design would need to be changed during construction,” said Stubbs. The original request for an initial signal sighting assessment resulted in 18 months of continuous work for the Mott MacDonald modeling team, which included three engineering technicians, an operations professional, and an engineering project manager. The firm is developing proposals to continue the process through the detailed design phase of the East London Line Project. Noted Eaden, “The initial phases of signal sighting yielded a measurable savings in time and costs, but these direct savings pale in comparison with the potential financial and schedule savings associated with the risks of errors at the detail design and implementation stages.” During detail design, for example, a change in position of a single signal could result in rework ranging from $40,000 to $100,000, not to mention several weeks of delay in the schedule. But if that same error arose in the procurement stage of the project, the costs and schedule implications would increase by a factor of 10. From the start Mott MacDonald intended the 3D model to deliver more value than simply assessing signal sighting. In fact, the model is now used to inform design decisions ranging from passenger evacuation analysis to interdisciplinary checks. The modeling process is designed to leave as many avenues as possible open to exploration. For instance, the savings from using the 3D models to train drivers is estimated to be over $6 million. design with increased confidence in the validity of the designs. The firm built a 3D model of the railway using MicroStation based on topographical surveys and current infrastructure designs, explained Mark Eaden, principal engineer at Mott MacDonald. “Signal sighting ensures physical obstructions cannot impede the sight lines to railway signals, and this can normally only be done effectively on site,” added Mike Stubbs, head of engineering on the East London Line Project. “The use of virtual reality simulations has enabled the signal sighting committee, as required by Network Rail standards, to assess the physical constraints and obstructions well before the railway infrastructure has been constructed, thus significantly reducing the risk of having to change things when on site.” About 80 signals will be positioned on existing infrastructure. Conservative estimates assigned a cost of $13,350 to $15,750 per shift spent on signal sighting, for a total project cost of $1.2 million. Mott MacDonald estimated that, as with most urban railways, the sighting v 3D simulations have enabled the signal sighting committee to assess physical constraints and obstructions well before construction committee could go out only at night and resolve signal sighting issues at a rate of one signal per shift on average, meaning that it would take as long as six months to complete the signal sighting, which was the total time allocated to design the signaling system. Over the six-month period, however, Mott MacDonald spent only $255,000 on the 3D modeling process and sighting committee meetings. The 12 kilometers of railway required more than 260 discrete models, including all aspects of the railway infrastructure that affects the signal sighting process. Visualizations were initially based on designs in development and then modified as the design progressed, which, of course, had to be completed quickly to confirm design decisions. The firm used an assortment of Bentley products, including ProjectWise, ProjectWise Navigator, Bentley Rail Track, and Bentley CloudWorx. “The modeling process highlighted the complexities of threading a 21st century railway through 19th century infrastructure,” said Eaden. “The alignment design broke many of the rules in the book, and the signaling scheme now employs some decidedly inventive solutions.” The New Cross Gate facility, for example, underwent several revisions during the project design. Initially, the plan was to house 10 to Modern Road to Historic Ruins Providing access to historic sites promotes economic growth for Navajo Nation I n the heart of Native American country, the people of the Wide Ruins Chapter of the Navajo Nation live on less than 150,000 acres set aside by the U.S. Bureau of Indian Affairs (BIA). One paved road runs through the chapter area in Arizona, giving the 1,200 residents access to nearby towns—19 miles south to Chambers and 23 miles north to Ganado. The Wide Ruins community grew up around the Wide Ruins Trading Post, built in the late 1800s to provision pioneering settlers 30 BE MAGAZINE | Volume 5, Issue 2
For optimal viewing of this digital publication, please enable JavaScript and then refresh the page. If you would like to try to load the digital publication without using Flash Player detection, please click here.