# Review of the Main Cable Shape Control of the Suspension Bridge
## 3 Construction Control Technology of the Main Cable
### Other Control Technologies  
Although strand manufacturing accuracy and overall quality can meet the requirements of cable shape control, there are some studies and attempts to improve the accuracy of cable strand production and to simplify the manufacturing process. For this purpose, [PERSON] et al. [87] invented an approach to control the manufacturing accuracy of cable strands by using a ruler wire. This methodology exploited a ruler wire to measure the standard wire in cable strands, which reduced the discreteness of deviation in the traditional production process of standard wire between cable strands. However, this method is very dependent on the standard wire, and once the standard wire deviates, it leads to more serious consequences. [PERSON] [88] developed a segmental suspension length measurement method to control the length of the cable, that is, when the cable strand was suspended freely, the length of the strand can be indirectly measured by controlling the alignment of the suspended strand. This approach can eliminate the influence of the elastic modulus and the steel wire diameter error on the stress-free cable length, and avoid the problem of artificial tension in traditional methods. However, this method has high requirements for manufacturing sites and is not used in practical engineering.  
Figure 12: Quantified inter-strand distance.  
Figure 13: Various control methods of the inter-strand distance.  
Additionally, [PERSON] et al. [89] suggested a novel lateral bracing-based method (LBM), which solved the problem of 3D curved cable configuration transformation for spatial suspension bridges. This is also the embodiment of advanced construction methods in the main cable erection process.  
To sum up, both the AS method and the PPWS method are focused on new technology, new equipment, and high-strength materials. Although the characteristics of the AS and PPWS methods are different, the adjustment of sag is the key to controlling the cable shape in these two approaches. The improved cable adjustment formula makes the cable strand erection calculation more efficient and accurate. The use of relative reference strands is the mainstream method to ensure the quality of erection, but there are also interesting methods such as the use of the ruler cable and mark method to erect cable strands, which enriches the means of cable strand erection. The measurement method based on machine vision undoubtedly provides a new idea for construction measurement. Although the relevant specifications stipulate the deviation range of cable erection, the error control standards of specific projects are still not uniform. However, quantifying the cable spacing to achieve cable pre-lifting is a commonly used method in current projects, but the quantitative values and control methods are different. In addition, the cable strand manufacturing and temporary construction equipment were studied to ensure erection accuracy. The above exploration undoubtedly promotes the development of the main cable shape control of suspension bridges.