4th Ring Transportation Corridor in Zhengzhou – Zhengzhou, Henan, China
The city of Zhengzhou, with a history of over 5,000 years, is a major transportation hub. Its 10.1 million population will increase by 5 million in the next years, making large infrastructure projects imperative.
The 4th Ring Transportation Corridor in Zhengzhou is an elevated viaduct expressway above the existing 4th Ring around the city center and increased the traffic capacity to 18 lanes.
Accelerated Bridge Construction with the precast segmental bridge technology was used for this Mega-Project. This largest precast segmental bridge project in the world was opened partially to traffic in 2020 and is now fully operational.
Innovation of Design and/or Construction
The elevated expressway has a total length of 58 miles and faced complex boundary conditions, with:
- 27 Main Interchanges with Additional 56 Miles
- 12 Railway Crossings
- 21 River Crossings
- Underground Utility Relocations
70% are elevated viaducts, while 28.4miles are segmental bridges for the main line and 31.1 miles for the interchange ramps. The viaducts were designed for a 100-year service life.
1,200 different bridge frames with only four basic precast segment lengths were designed for the entire elevated expressway. Most of the precast segmental bridges are continuous rigid frame systems without any bearings, consisting of 3-4 spans, ranging from 112 ft. to 151 ft. for each span.
Only five basic precast segment forms were used for the fabrication of 50,000 unique segments. Many variations of span length, varying width, and ramps with small radius, could be produced with these precast templates.
The general design concept was to build the viaducts in the center (two piers with prestressed pier-caps, two single cell precast box girders) or, if not possible, at the outsides of the existing road (single cell precast box girder on an integral pier).
The total project area, including surface roads and bridge viaducts:
- 4 million sq.ft.
- 212 million c.ft. of concrete
- 2 million tons of steel
- 50,000 segments
Another remarkable aspect are the precast yards. Eight completely new precast yards with over 400 stations were designed and ready for production within five months. The locations of the eight precast yards were strategically selected with a cost-distance analysis to guarantee an ideal workflow. A state-of-the-art data management system and geometry control software was combined to analyze millions of data daily. This entire paperless process was extremely efficient, allowing the production of 200 precast segments every day.
Rapid Construction
An astonishing achievement is the fabrication and erection of 50,000 precast segments within only 40 months, which are world records for both fabrication speed (50,000 precast segment within 18 months) and number of precast segments for a single project. Eight completely new precast yards with over 400 stations were designed and ready for production within five months. At an average speed, the eight precast yards produced 200 segments per day. A fabrication cycle of only 1.5 days per segment was achievable at peak times.
Given the large number of continuous bridge frames, ramps, and special bridge frame structures on high piers, the balanced cantilever erection method was the ideal choice. The contractors could choose their preferred erection equipment, varying from overhead gantries, travelers, mobile cranes, portal cranes, or simple falsework. A segment pair was erected in five hours and a span was completed in only two days. The bridge contractors were able to work at multiple locations – at peak times there were 50 bridge erection sites at once. The erection speed for the precast bridge frames was an average of 2,600 ft/day, with a maximum erection speed of 4,900 ft/day. A management platform was utilized to assist the owner to monitor the project schedule and resources at all times.
Aesthetics and/or Harmony with the Environment
An urban public space was designed along the 4th Ring Transportation Corridor. The landscape will be cohesive and consistent to integrate the ecological concept of the city. The green belt around the city will enhance the quality of life, including bike lanes, running tracks and recreational areas. These green areas are also essential to reduce the urban heat island effects.
The superstructure of the elevated bridge viaducts with the constant shallow bridge section presents a simple and slender design, with longer spans and fewer piers, successfully resulting in an aesthetically pleasing and economical solution. The two piers at the center section were tapered 1:30 from the bottom up to express a sense of rising strength. The single piers at the outside present a slimmer and more elegant shape, with the aesthetically pleasing combination of elegant superstructure and unique piers, the bridge design presents a kind of strength and softness at the same time.
The precast segmental technology using the balanced cantilever erection method shortened the construction time and minimized the temporary environmental impacts. The innovative design made an extreme effort to save construction material, which translated to a reduction of 560,000 tons of carbon emissions.
Cost Competitiveness
- Total Project Cost was $7.1 billion
- Average Construction Cost for the Elevated Viaducts $88/sq.ft.
The 54.1 ft-wide and 7.2 ft-deep single-cell cross-section with longer overhangs, reduced material usage by 15%, compared to conventional bridge cross-sections. The structural frame system with fewer bearings will reduce the maintenance cost.
Minimization of Construction Impact on the Traveling Public
From the onset, one of the important project considerations was the need to keep continuous traffic flow during construction. With the precast segments being fabricated in the precast yards off- site, reduced the amount and duration of work performed along the 4th Ring Corridor. The elaborate planning of the eight precast yard locations avoided long transportation routes, reduced traffic impact, and led to transportation cost savings. Due to this accelerated bridge construction process various sections were opened earlier, which also helped to reduce the traffic impact. With no traffic lights on the elevated expressway, the speed limit could be increased from 60 km/h to 80 km/h reducing the travel time around the whole loop tremendously from 4-6 hours to 1-2 hours.
Jury Comments
Great planning and execution on a very large scale. The magnitude of this project and the speed of design and construction is nothing short of astounding. It would be very difficult to accomplish this project with construction methods other than segmental. A very attractive project as well. A true factory setting for casting of segments created huge advantages in quality and cost effectiveness.
2021 ASBI Bridge Award of Excellence
Category: Urban Bridges (Within City Limits)
Designer:
Shenzhen Municipal Design & Research Institute Co. Ltd., SUN Engineering Consultants International, Inc., T.Y. Lin International Engineering Consulting China Co. Ltd., Henan Provincial Communications Planning & Design Institute Co. Ltd., and Zhengzhou Transportation Planning Survey and Design Institute
Contractor:
Henan First Construction Group, Henan Fifth Construction Group, Zhengzhou New Dafang Heavy Industry Science and Technology Co. Ltd. Zhengzhou, First Construction Group Construction Engineering Co. Ltd., TIHOME Construction and Development Co. Ltd., China Construction Seventh Engineering Co. Ltd., China Railway 21st Bureau Group Co. Ltd., China Tonghao (Zhengzhou) Electrification Bureau Electrical Service Company, Zhengzhou Municipal Engineering Corporation, SINOHYDRO Bureau 11 Co. Ltd., China Railway Engineering Group Limited, and CCCC First Highway Engineering Group Co. Ltd.
Construction Engineering Services:
SUN Engineering Consultants International, Inc. and SUN Engineering & Technology International, Inc.
Construction Engineering Inspection:
Henan Wanan Engineering Construction Supervision Co. Ltd., Henan Gaojian Engineering Management Co. Ltd., Henan Guangda Construction Management Co. Ltd., Zhengzhou Hengji Construction Supervision Co. Ltd., and Gansu Tieke Construction Engineering Consulting Co. Ltd.
Precast Producer:
SUN Engineering Consultants International, Inc., SUN Engineering & Technology International, Inc., Zhengzhou New Dafang Heavy Industry Science and Technology Co. Ltd., Henan First Construction Group, Henan Fifth Construction Group, Zhengzhou Construction Group Construction Engineering Co. Ltd., TIHOME Construction and Development Co. Ltd., Zhengzhou Municipal Engineering Corporation, and Zhengzhou Urban Construction Group Investment Co., Ltd.
Formwork for Precast Segments:
Guangzhou Luyu Construction Machinery Engineering Co., Ltd. Tianjin, Liandong Dongxingda Technology Co., Ltd., Zhuozhou Sanbo Bridge Formwork Manufacturing Co., Ltd., Hunan China Railway Wuxin Steel Membrane Co., Ltd., Shandong Boyuan Heavy Industry Co., Ltd., and Shandong Zibo Huanyu Bridge Formwork Co., Ltd.
