Delaware Memorial Bridge USA

The Project

The United States of America, the land without borders, freedom without end. And everything is a little bigger than in Switzerland. Who doesn't dream of a trip to the land of unlimited possibilities? WALO International has been working in the USA for five years now and was given the opportunity to repair the concrete deck on the Delaware Memorial Bridge.

The Bridge

WALO International is carrying out the contract to repair the concrete deck with an ultra-high performance fiber-reinforced concrete [UHPC] overlay. The bridge to be renovated was opened on August 16, 1951. 71 years ago, Otmar Ammann, ETH engineer from Feuerthalen (Schaffhausen), was able to inaugurate his first bridge at a cost of 44 million US dollars: 3281 meters long, 18 meters wide. The bridge connects the two states of New Jersey and Delaware, around two hours south of Manhattan. WALO International now has the major task of repairing the bridge. Construction volume around 72 million US dollars.

Project 2022/2023

The project provides for the following maintenance measure:

- Private traffic must always remain intact in two lanes.

Exception: During 6 hours at night, one lane can be closed to private traffic for UHPC installation (logistics for UHPC transportation).

- Barriers with New Jersey elements (safety barriers) along the entire length

- Remove the existing concrete slab surface by approx. 7 cm using HDW (high pressure water jetting or pointing) over an area of 51,184m²

- Expose up to 70% of the existing reinforcement

- Cleaning/preliminary work UHPC

- Installation of UHPC, minimum final thickness 5.1 cm / corresponds to an installation of approx. 7 cm on approx. 4,000 m³

- Grinding and grooving the surface

- Remove all existing steel joints with rubber profile and reinstall using a flexible polymer joint

- The project includes 4 construction phases of around 12,800m² each.

Offer and award of contract

The tender was prepared in collaboration with the responsible parties from the USA and Walo Bertschinger AG, Zurich in fall 2021. The submission was made on December 29, 2021, and the client received a total of two submissions. In March 2022, the contract was awarded and signed for us as joint venture partner UHPC Solution North America with 50 percent each of Walo International and Posillico AG, Long Island.

Work preparation

Repairing such a large bridge with UHPC has never been carried out in this time frame, neither in Europe nor in North America. We started the AVOR back in February 2022. Our aim is to complete the bridge in three stages instead of four. In the fall of 2022 and 2023, a quarter of the surface each and half of the bridge in the spring of 2023.

When working with UHPC, the process must be thought through from the production of the UHPC to its application. The biggest challenge is the long transportation route from the mixing plant to the point of use. Contrary to the tender, we changed the installation concept and opted for two mobile concrete mixing plants on the bridge. This concept enabled us to kill two birds with one stone. Firstly, the transportation routes are very short and secondly, we no longer need the third lane at night. The systems were planned and built as a prototype within six months. This was followed by the planning of the individual work steps before we were able to start on September 6, 2022.

Construction site phase 1 (fall 2022)

The weather threw a spanner in the works right at the start. The marking cannot be carried out in the rain. So we were already three days behind schedule at the start. The New Jersey was then laid and the installation for the HDW work started. Unlike here in Europe, fresh water is not available everywhere in this large country. Fresh water can only be obtained at night, which initially caused us major problems and the planned work could not be carried out on schedule. An American thinks differently to a European. The American wants to do as many surfaces as possible and not the details (joints, connections etc.) at the same time. So now we had a difference in mentality and WALO International had to send more employees to America. After another lost seven days, the system was turned around thanks to the great help of our additional Swiss employees and it started to run. All subsequent work was completed with a large workforce and on October 8, 2022, the first UHPC was installed ten days late. We asked ourselves, would there be enough time to complete phase 1 by November 22? Thanks to the valuable support of our Swiss colleagues, we were able to make up time on the UHPC and completed the UHPC installation on October 30, 2022 - a success! This work was followed by the grinding and grooving work, which is not dependent on the weather. The jointing work was carried out at the same time as the grooving. The recommissioning of the first quarter has been completed.

Different cultures

Otmar Amman probably had to struggle with the different cultures even in his early years in America. But his will was so great that he succeeded and is now a bridge-building legend. Seventy years later, we are doing the same, we are doing our best. It is absolutely important to understand the mentality of the Americans and to subordinate ours.

Americans don't think very far ahead, but they organize better and faster than we Swiss. Their way of working means they are not as efficient and work like they used to in the military: segglä - wartä.

We Swiss don't have to hide, we have to take on this huge challenge and in cooperation with the Americans we will achieve the best performance in the future. Our job will be to pass on our technical know-how and achieve a mechanized and organized execution.

The performance that all Walo Bertschinger AG employees have put in abroad is simply fantastic and top-notch. Everyone involved can look forward to the next stage in spring 2023 with great pleasure.