Design and Construction of the Carmel Tunnels in IsraelThe old part of Haifa, Israel and its major business district and port are located on a narrowish coastal promontary beneath 550 m-high Mount Carmel, part of a range which forms a barrier, forcing through traffic to hug the coast and go through Haifa. Much of the high ground is now developed but Carmel roads are steep and winding. To solve urban traffic problems, a tunnel project has been imagined to relieve congestion downtown and provide improved connections to the residential areas around the mount, via the Giborim valley. The overall project includes two pairs of twin tunnels, five conventional bridges, three precast and three cast-in-place segmental bridges and 11 kilometres of roads with corresponding civil improvements. Current travel time through Haifa is 30 to 60 minutes. Anticipated travel time after completion of the Carmel tunnel project is seven to 10 minutes.The project of the Carmel tunnels will connect the districts of Carmel Beach and HaKerayot in the city of Haifa by means of a four-lane expressway. The entire project is 6.5 km long and includes two western and two eastern tunnels with a total length of approx. 9,400 metres. Between the western and eastern tunnels, an interchange is foreseen to connect the residential areas of Rupin with the expressway. Each pair of parallel tunnels will carry four lanes (two in each direction).The proposed system of tunnels and interchanges runs east-west right under the summit of Mount Carmel. Going from the west at Carmel Beach under the main mount will be the first, eastbound tube of a pair of two-lane mixed traffic tunnels sloping up at a grade of 3.5% and approx. 3.1 km long each. They emerge into the Giborim valley, a residential area overlooking the city and bay below. The expressway is to span the valley on a 500 m-long bridge with ramps to the Rupin interchange to connect with local traffic. Then continuing east, traffic enters the portal of one of another pair of similar two-lane tunnels sloping steeply (6%) down for just approx. 1.6 km emerging at an interchange at HaKerayot, west of Haifa. The NIS1.25 billion Carmel tunnel project was launched in 1996 with the publication of a BOT (build, operate, transfer) tender whereby a concessionaire would build and operate the toll infrastructure for 35 years. The Carmelton consortium, which won the tender in 1998, consisted at the time of Dragados (40%), Ashtrom Group (20%), Property and Building (20%) and FIBI Holdings (20%). The project's completion was scheduled for 2002 but it was delayed several times by statutory problems and financing woes. Carmelton Group is currently a partnership of only Ashtrom Group (50%) and Housing & Construction Holding Co. (Shikun & Binui, 50%). The project is financed by the Israel Discount Bank. The project's expected completion is in late 2010. Click il/14. Visit www.carmelton.co.il, www.ashtrom.co.il and www.hch.co.ilThe tender and detailed design for the tunnels was elaborated by WBI in 2006 on behalf of the Carmel Tunnels Joint Venture (CTJV), which consists of the two Israeli contractors Ashtrom Engineering & Construction and Solel Boneh. CTJV received a design and construction contract from the concessionaire. It then subcontracted the tunnel construction to Chinese contractor China Civil Engineering Construction Corporation (CCECC). Six hundred Chinese workers have been brought in for the project. Visit www.solbo.co.il, www.wbionline.de and www.ccecc.com.cnDerech Eretz Highways has just signed a memorandum of understanding (MoU) with Carmelton to operate the tunnels and collect the tolls. Derech Eretz is owned by Africa-Israel Investments, Housing and Construction (37.5% each) and Canada's Aecon Group (25%). Visit www.derech-eretz.comDue to the Israel-Lebanon war in 2006, the actual start of the contract was further delayed, but in April 2007 the project commenced with the preparation of the portal areas. The tunnels will have three portals: one from the west and two from the east (one from Rupin Road and one leading to the HaKerayot interchange). The portals are a construction of retaining walls, with soil nailing. As part of the project, Kedmor Engineers designed the portals and control centre of the tunnels, which will include toll administration offices and energy generators. Click here for more on Kedmo. Visit www.kedmor.co.il GeologyThe western tunnels pass through layers of conglomerate, chalk, limestone, tuff and dolomite (from west to east). The eastern tunnels cross faulted and massive layers of dolomite. The overburden above the western tunnels is max. 210 metres while above the eastern tunnels, it results to max. 140 metres. The tunnel lies above the groundwater table.Tunnelling methodologyExcavation uses the drill-and-blast method with explosives, in six headings with hand drill boreholes and in two headings with jumbos. One Atlas Copco LTC jumbo is employed for both tubes. Visit www.atlascopco.comA blast cycle is achieved in five phases: 1) drilling of blast holes, 2) loading of explosives, 3) blasting, 4) mucking-out by loaders and dump trucks, 5) rock reinforcement: shotcreting, face support with shotcrete and fibre glass anchors (if needed), wire mesh (if needed), lattice girders (if needed), shotcreting, anchors and mortar spiles (if needed), shotcreting, wire mesh (if needed), shotcreting, and final lining with shotcrete. Then a new round commences. Computer rendering of the west portal The total length of the western tunnels is 6,199.5 metres. To date, crews have excavated 3,410 metres (55%). The eastern tunnels stretch for 3,295.2 metres altogether and 1,605 metres is finished (48.7%). The twin tunnels are connected by 18 crosscuts at 250 m intervals (12 pedestrian and six vehicular with lay-bys, allowing truck access). By now, five of them have been excavated. Work on the Carmel tunnels is proceeding faster than anticipated and the section between Haifa's Grand Canyon and the HaKerayot intersection in the west is expected to be completed by the end of the year, several months ahead of schedule.But in the meantime, in response to complaints by residents, the Ministry for environmental protection has ordered the builders to carry out no more than three blasts per day inside the tunnels, and also to limit their intensity. Following complaints by residents, the ministry measured the intensity and number of blasts during May, and found four breaches of the limits. The contractor has been warned not to exceed the noise limits, and said every breach would be examined. Computer rendering of the Rupin interchange bridges and eastern tunnel portal Rock reinforcementDue to the low uniaxial strength of the tuff and the maximum overburden of 210 metres in this section, squeezing rock conditions have to be expected, which was accounted for in the design by means of a yielding support with a slotted shotcrete membrane.The temporary and final support of the tunnels mainly consists of bolts and a shotcrete lining with different thicknesses, partly only reinforced with steel fibres. In the six manual headings, support consists of dry-mixed shotcrete (thickness of 10-60 cm), steel fibres and/or wire mesh. In the two jumbo headings, support combines wet-mixed shotcrete (10-35 cm thick), steel fibres and/or wire meshes.In all headings, support needs only shotcrete, anchors or additional reinforcement with lattice girders and mortar spiles (depending on rock conditions). The shotcrete is the only lining, there is no further concrete. In all headings, 25 mm-diameter, 3-6 m SN anchors for support and permanent anchors for the lifetime are installed. Bad rock conditions require lattice girders, 28 mm-diameter 3.5 m-long mortar spiles and face support with 25 mm-diameter 6 m-long fibre glass anchors.The mortar anchors, permanent anchors and self-drilling anchors are supplied by SUSPA-DSI Geotechnik, the wire mesh by Neumann Steel Industrial and the lattice girders by Tunnel Ausbau Technik (TAT). The steel supports are placed with Manitou handlers. Visit www.suspa-dsi.de or www.dywidag-systems.com, www.neumannsteel.com.au, www.tat-befer.de and www.manitou.comThe shotcrete is produced at two headings by Readymix. Admir Technologies is the supplier of the steel fibres. Visit www.readymix.co.il and www.admir-geo.com Construction managementSince January 2008, approximately half a year after tunnelling had started, WBI is permanently present on the site for the construction management on behalf and upon request of CTJV. As a consequence of re-assessing the significant management tools and re-organizing the collaboration between CTJV and CCECC, the project performance improved considerably. The rate of advance of the tunnel faces in chalk and dolomite increased to 40-45 metres per week although blasting is only allowed from Sunday to Friday at noon.Furthermore, the intensive cooperation between WBI's construction manager, its design office in Aachen, Germany and the client enabled several modifications of the design in order to optimise it for the excavation techniques and the equipment used by the Chinese subcontractor. Construction underway at the eastern tunnel portal at the Rupin interchange in November 2007 From each side of each tube of both tunnels there is a heading, which means there are eight headings. The headings from the Carmel Beach portals have crossed the 1 km-long section in the conglomerate, chalk and limestone layers. Recently, the tunnel faces have reached the tuff. Meanwhile, the rate of advance at all sites as well as the quality of the works carried out by CCECC exceed the expectations of the client. 31/08.