Loca­tion: Ham­burg
Time­frame: 2021 to 2028
Cli­ent: DEGES
Con­s­truc­tion: Hafen­bahn­tun­nel Joint Ven­ture – AUGUST REINERS Bau­un­ter­neh­mung GmbH (TGF) | Bauer Spe­zi­al­tief­bau GmbH (KGF)
Detailed design: Ram­boll Deutsch­land GmbH
Con­s­truc­tion method: Open-cut construction

Con­s­truc­tion Phase 4 of the A26 will create a con­nec­tion bet­ween the Hamburg/Lower Sax­ony state bor­der and the A7. Part of this phase is the Hafen­bahn Tun­nel, through which the future A26 will pass under the tracks of the Ham­burg Hafenbahn. 

At km 0+590, the A26 route cros­ses the Hausbruch–Waltershof port rail­way line. Here, a two-cell tun­nel struc­ture appro­xi­m­ately 200 m long is being con­s­truc­ted from water­proof con­crete using the “white box” prin­ci­ple. To the east, it con­nects to a trough ramp appro­xi­m­ately 70 m long; to the west lies the por­tal area. 

The uni­que geo­tech­ni­cal con­di­ti­ons and ground­wa­ter situa­tion repre­sent one of the key chal­lenges in the con­s­truc­tion of the Hafen­bahn Tun­nel and play a decisive role in deter­mi­ning the cho­sen con­s­truc­tion methods and the con­s­truc­tion sche­dule. In par­ti­cu­lar, dewa­te­ring, soil manage­ment, and ground impro­ve­ment pose signi­fi­cant tech­ni­cal and logi­sti­cal chal­lenges throug­hout the entire con­s­truc­tion period. The sub­grade, which con­sists pri­ma­rily of peat and silt, has only a low bea­ring capa­city. Exten­sive mea­su­res to improve the sub­grade and to create sta­ble working sur­faces and con­s­truc­tion roads are the­r­e­fore neces­sary even for site operations. 

The excava­tion pits will be enc­lo­sed using sheet piles, and bored pile walls will be used in the area of the exis­ting har­bor rail­way embank­ment. Inside the excava­tion pits, the non-bea­ring soil will then be excava­ted using the wet dred­ging method. Divers are used to dredge the bot­tom of the excava­tion pit and prepare it for fur­ther work. The resul­ting mix­ture of soil and water is trea­ted and sepa­ra­ted through a com­plex pro­cess. This invol­ves the use of, among other things, sepa­ra­tion sys­tems, sett­ling tanks, floc­cu­lants, and geo­tu­bes. To dewa­ter the excava­tion pits, ver­ti­cally ancho­red under­wa­ter con­crete bases will then be con­s­truc­ted. For this pur­pose alone, we will pour a total of appro­xi­m­ately 18,350 m³ of under­wa­ter con­crete, of which appro­xi­m­ately 7,850 m³ will be in the eas­tern sec­tion and 10,500 m³ in the wes­tern section. 

Addi­tio­nal requi­re­ments regar­ding con­s­truc­tion methods, equip­ment use, and con­s­truc­tion site logi­stics arise from working under exis­ting high-vol­tage power poles and in the imme­diate vici­nity of the ope­ra­tio­nal har­bor rail­way. Main­tai­ning port rail­way ope­ra­ti­ons during the con­s­truc­tion period also requi­res divi­ding the excava­tion pit and tun­nel struc­ture into a wes­tern and an eas­tern con­s­truc­tion sec­tion. The Har­bor Rail­way Tun­nel is desi­gned for one-way traf­fic, with two main lanes in each direc­tion. In addi­tion, there are two entry lanes hea­ding toward Stade and one exit lane hea­ding toward Ham­burg. The tun­nel seg­ments, which are gene­rally 10 m long and over 30 m wide, are con­s­truc­ted in sec­tions. First, the floor is pou­red, fol­lo­wed by the cen­ter wall. The com­ple­tion of a tun­nel seg­ment invol­ves the simul­ta­neous pou­ring of the outer walls and the cei­ling. Ano­ther distinc­tive fea­ture of this con­crete con­s­truc­tion is the crea­tion of the trough sec­tions using com­plex relief formwork. 

In the future, four tracks of the Ham­burg Port Rail­way will run through the tun­nel: two through tracks and two siding tracks. In addi­tion, the struc­tu­ral foun­da­ti­ons are being laid for a pos­si­ble future expan­sion of the track lay­out by the HPA. The pro­ject also includes exten­sive ope­ra­tio­nal and drai­nage sys­tems. At the eas­tern por­tal, an ope­ra­ti­ons buil­ding, a fire­wa­ter reser­voir, an emer­gency sto­rage basin, a storm­wa­ter pump sta­tion, and a sedi­men­ta­tion basin are being con­s­truc­ted. Ano­ther fire­wa­ter reser­voir is plan­ned for the wes­tern portal. 

Ano­ther uni­que fea­ture of the pro­ject is the inte­gra­tion of soil manage­ment and land­sca­ping: Excava­ted mate­rial from the con­s­truc­tion pits of the har­bor rail tun­nel is being reu­sed to build the green bridge. This includes a bat flight route, a farm road, a green cor­ri­dor con­nec­ting the exis­ting green cor­ri­dors, and a land­sca­ping fea­ture adja­cent to the south. The Hafen­bahn Tun­nel thus com­bi­nes, within a con­fi­ned space, sophisti­ca­ted engi­nee­ring and spe­cia­li­zed civil engi­nee­ring with road and rail infra­struc­ture, as well as high demands on the con­s­truc­tion site, dewa­te­ring, and con­s­truc­tion sequencing—all while Hafen­bahn ope­ra­ti­ons continue.