Blog 3
Blackfriars Railway Bridge

Blackfriars Railway Bridge

Structure Information

The new Blackfriars Railway Bridge began development in 2008. The cost was estimated around 350 million pounds [2]. The bridge opened in February 2012 and began operation the following summer. The new bridge was a part of the Thames Link Project by Network Rail and First Capital Connect to decrease congestion and increase capacity of the passenger train routes in London [2]. Tony Gee and Partners of London designed the station-bridge and Jacobs designed the building [2]. The Department of Transport’s Safety and Environmental Fund funded the solar panels [2].

Figure 1: Blackfriars Rail Bridge

Historical Significance

The Blackfriars Rail Bridge has 4,400 photovoltaic panels that provide up to half of the energy for the London Blackfriars station located within [1]. The bridge is the world’s largest solar powered bridge and the largest solar array in London [1]. These panels required careful design and installation. They needed to be light so prevent exuberant additional load on the structure and crack resistant, for safety. The instillation also had to be paused for the London 2012 Olympic games.

Blackfriars Rail Bridge is also completely accessible to travellers with disabilities. Although this seems like the norm, it is quite uncommon in London [5]. On the tube it is particularly noticeable that only a few stations are handicap-accessible, this, however, could be due to the old age of the underground system in London. Even the accessible stations seem to be a challenge with ramped corridors and gaps getting into the trains. The new rail bridge station makes it easy for travellers with disabilities to make their way on the bridge and through the station.

The new Blackfriars Rail Station is the first in London to span the entire length of the Thames [2]. The deck station allows station access from both sides of the bridge and therefore both sides of the river [7].

The bridge also used innovative construction techniques to keep the lines functioning in the station and not impede traffic on the Thames. Most major new features (concrete pieces and steel arches) were prefabricated and brought in on barges and placed by cranes held by the old Blackfriars Road Bridge piers. The designers, Tony Gee & Partners, said that half of the work in the Blackfriars renovation and rebuild was construction engineering (figuring out how they would put their plan into action without much public disruption) [5]. See the rail bridge piers in Figure 2.

Figure 2: Blackfriars Road Bridge Piers

Blackfriars Rail Bridge exemplifies ideal features of modern bridges. The embodiment of Green structures and inclusion cover the main goals of society today. These two features alone make the bridge and station a perfect model for future buildings. The creative and efficient construction process also model futuristic construction, although each project differs in this regard.

Cultural Significance

The Blackfriars Rail Bridge is located above the remains of the original Victorian railway station [5]. This caused obstacles in the design process, yet it remains as a historic passageway, following the foundations of the existing bridge across the Thames.

The construction and rehab of the new and improved Blackfriars Rail Bridge was managed with both railways operational most of the time and without disturbing Thames traffic [5]. This connects to the true significance of the bridge, smooth passage in London. The station relieved previous congestion and has provided easy travel for all passengers, including those with disabilities. The train station located on the deck allows 12 car trains to function and permits over 24 trains per day to pass through [1].

Since the construction, the bridge has served as a reminder of London striving to become a sustainable city with its central location and functionality during the Olympics [1]. It is now considered an “Iconic Landmark” [6]. This rail station also, for the first time, connects London’s “cultural quarter”, the South Bank to a mass transit system [7]. This new location sparked conversation over renaming the bridges to “Blackfriars and Bankside” but, as we see today, this was never pursued [7].

Structural Art

The Blackfriars Railway Bridge is not a quintessential example of structural art. However, the Blackfriars Railway Bridge seems like a modern example of structural art. While it does have expensive features, each of these contributes to the efficiency of the bridge. The solar panels make an efficient green structure and the handicap features simply satisfy the necessities of today’s facilities. The extension of the deck allows for larger trains, which are occupied and will be heavily used as London’s population skyrockets. The foundations built off of existing structure and reinforced bracing, saving money and contributing to economy. The use of the existing road bridge piers and prefabrication also contributed to economy. The load path is clear and elegant, as the arches flow across the Thames. It seems clear that the Blackfriars Rail Bridge and Station are structural art.

Structural Analysis

Blackfriars Rail Bridge is a wrought iron girder bridge with five arches [4]. Much of the originally wrought iron deck has been replaced with mild steel and concrete [4]. The foundations are made of wrought iron plated caissons [4]. The piers are concrete and stone, converted with granite and sandstone [4]. The abutments are made of cross arches of brick. The bridge acts as five separate arches as arch girders on the piers and abutments, which take the deck and arch load [4]. This could partially due to the bridge being built over an existing railway, which, at its time, had no standardization. Each precast concrete structure had to be individually measured and made off site [5]. A quick-stiffening concrete was needed so the pieces could be handled soon after being cast. The steelwork was also pre-assembled and brought in by barge. The existing piers from the old Backfires Road Bridge were used as support for equipment in demolition and expansion of the existing rail bridge. The existing rail bridge was reinforced to allow for the addition of lanes for trains.

Load Path

The loads on the deck are assumed to evenly distribute onto the arch. From here the arches send the load to the piers or abutments on either side of them, which translate the load to the ground. The load path can be seen in Figure 3.

Figure 3: Load Path

Info

Figure 4: Span Information [4]

Blackfriars Rail (m) 6.9 6.9 7.0 7.2

[8]

Passenger trains have a maximum live load of 1.71 tons per foot.

There are 15 steel arched members per arch.

Each arch weighs 45 tonnes [3].

Solar Panels each weigh 15kg  and there are 4400 of them [1].

Calculations

Each arch varies in size, and therefore produces a different load. Since the bridge built from a pre-existing structure, the piers are large enough to handle some of the force from the arch. Because of this, I assume all differing horizontal forces cancel through the piers although they are not equal. The dead load embodies the load of the steel and concrete deck and steel arches and the live load includes the train and people load. With this information, the reaction forces of each arch were calculated. These calculations are in Figure 5.

 

Figure 5: Calculations

Drawings were used to communicate the design to the stakeholders in order to show that components of the existing bridge could be retrofitted for the new bridge. By expressing this, the designers showed their cost effective solution for the congestion at this central London location. The drawings also conveyed the importance of handicap accessibility and energy conservation and how they were employed to the new bridge and station.

Personal Response

            By visiting the bridge and walking through the station, I saw first hand the attention to detail put into the structure. The combination bridge and station, green initiative of London, and handicap inclusion are all striking from within and around the structure. I also saw the true extent of 4,400 photovoltaic panels crossing the entire Thames. The bridge panels even stuck out from the top of the London Eye, which is when the bridge first struck me.

Comments

  1. ezaruvinsky3 says

    Thats awesome that the bridge is completely accessible for everyone! My last blog post on a pedestrian bridge in Geneva, Switzerland was also built for this purpose and I love how it united the city and made everyone feel welcome.

    • kkpetsu3 says

      Great insight, I did my previous blog about the Blackfriars bridge next to this one and their stories are impressive! More impressed about the sustainability that has been highly considered during this railway project. Just wondering if the solar panels could at any point been extended in order to make the station totally green energy powered.