Extraordinary pile lengths - 10 bridges for VT12 Ringway South of Lahti stand on large diameter RR® and RD® piles
LETKE Project part 1A is including bridges, undercrossings, bridge crossings and interchanges. Main contractor for the project is Destia Engineering Oy. Design & Build contract has required very good co-operation with material supplier. When design work continues throughout the project, open dialogue and fast deliveries are essential. “This method of implementation requires open dialogue and good co-operation between contractor and material supplier. SSAB has succeeded very well in the project and our co-operation has been good. SSAB’s fast reaction to our needs and deliveries on short notice have been very important for us”, says Jussi Kinnunen, Destia Engineering Oy.
The project consist of all together 10 bridges standing on large diameter piles, which have been delivered from SSAB’s Oulainen tube mill. There are both drilled RD piles and driven RR piles. In addition there are 4 temporary bridges. Steel piles RR270 and RR320 have been delivered for those bridges from SSAB’s Pulkkila tube mill. All piles were in S355J2H steel grade.
There are challenging ground conditions in the project; thick soft soils and very inclined bedrock surfaces.. “Pile lengths have been up to 72 meters in this project. Ground conditions have been challenging and also varying a lot in the project. There have been long pile lengths just next to rock excavations. We can say that 30 meter piles have been short ones in this project”, describes Jussi Kinnunen about the circumstances of the piling work. The longest pile elements delivered for the project were 18 meters. Thanks to the tailor produced lengths the splice welding at the site was minimized. Designed pile lengths based on the soil investigations were quite accurate in this project.
Luhdanjoki bridge S9B is the largest bridge of the project. Soft soil layers are exceptional thick and bedrock surface is partly sharply inclined.. The pile foundations consist of RR1000/16, RR1000/18 and RR600/12.5 piles. Piling work was executed during August – December 2018. Pile lengths varied between 50 – 72 meters. There was in total 1 500 meters of RR1000 piles and 600 meters of RR600 piles driven for Luhdanjoki bridge.
Up to 72 meter pile lengths were needed for the Luhdanjoki bridge S9B, which is the largest bridge of the project.
Project 1A is part of VT12 Ringway south of Lahti –project, which aims at securing smoother and safer traffic on busy highway VT12 and promote the development possibilities of land use and business life on the whole Lahti region. Owner of the project owner is Finnish Transport Agency. The project consists of three contracts: 1A, 1B and 2. In addition to the contract 1A, SSAB is delivering steel piles also for parts 1B and 2. Contractor for the part 2 is Suomen Maastorakentajat Oy and for the part 1B VALTARI alliance consisting of Skanska Infra Oy and Pöyry Finland Oy. First deliveries for the Project 1A started in summer 2018 and the piling works continue during 2019.
One of the first bridges in the project, Vähäjoen YKS S7B, being built in summer 2018. (Image courtesy Seppo Kujanen 2018)