ROAD TUNNELS | TRANSPORT


REFLECTIVE GAINS Providing a long-awaited solution to the congestion that


plagued the Blackwall Tunnel for decades, the Silvertown road tunnel was opened in April 2025. Designed to enhance cross-river connectivity and reduce journey times, the project also represents a significant advancement in tunnel safety and surface protection, supported by MC-Color T 21 from MC-Bauchemie. During early project development and construction,


Riverlinx CJV approached MC-Bauchemie to explore coating options to meet demands for reflectivity, cleanability, fire- behaviour and long-term performance. The MC-Color T 21 product was then a newly launched high-performance tunnel coating and its was selected, making Silvertown the largest project to use the product to date. MC-Color T 21 has a high light reflectance value (LRV) ≥ 70%, which exceeds the requirements of the BS 5489- 2:2016 that requires minimum wall reflectance of 60%. An independent third party performed reflectivity and luminescence measurements on-site. Silvertown had an 22,400m2


application area, with MC-


Color T 21 used in white colour for the main coating but also green and orange to mark safety passages and exits. No special substrate preparation beyond standard high- pressure water jetting to remove dust, and application of the coating was completed within one month. Standard procedure was one coat of MC-Color Primer followed by two coats of MC-Color T 21, all applied using airless spraying. The product has single-component formulation, which helps with ease of application, eliminates mixing errors and provides for unlimited working time. Compared to conventional resin coatings, it cures independently of ambient humidity and condensation. It has a touch-dry and overcoating time of a little over an hour and a full curing time of a day. For strength, breathability and durability, the product was


developed with acrylate elements densely cross-linked in the microstructure in a similar manner to reaction resin systems. This approach to strengthens the macromolecular cohesion of the coating film, making it far more robust than traditional dispersion paints and standard concrete


Above: Highly effective illumination and reflectivity were vital in the operational design of the tunnel PHOTO CREDIT: RIVERLINX CJV/JOHN ZAMMIT


protection coatings. Its high resistance to cleaning and abrasion is comparable to that of two-component reaction resins, which is important for high-demand infrastructure environments, such as tunnels. The product was also developed to have high diffusion


capability of water vapour, allowing moisture from the substrate to escape. Traditional epoxy and polyurethane (PU) resins can trap residual moisture, which may cause some blistering or delamination. This ‘breathability’ extends the coating’s service life and it being UV-resistant (preventing yellowing and fading) are valuable for tunnel maintenance needs, which may require closures. Additionally, the product is classified as non-flammable according to A2-s1-d0 for fire behaviour, placing it in the best-in-class category among conventional tunnel coatings.


Apurv Kesarkar Global Product Line Manager, Concrete Repair & Surface Protection, MC-Bauchemie


The engineering journey to create and operate the


1.4km-long, 10.8m-diameter twin tubes included many aspects. The technical push by the contractor, Riverlinx CJV (comprising Ferrovial Construction, BAM Nuttall and SK ecoplant), went beyond many major excavations, such as for shafts and TBM bores, and ground freezing, to also looked to the spatial experience, including well- lit spaces. Technical inputs ranged from large, heavy civils works


needed for efficient, economic and safe construction of the tunnels to also include fit-out equipment and suitable finishes for sight and more, to support guidance and safety.


Appreciation of good visibility comes most, perhaps,


not when it is lacking but when it is well provided for - such as through effective lighting and associated reflective surfaces, such as has been provided at Silvertown road tunnel. It is a customer experience. Support to tunnel illumination is becoming more


important. In addition to supplying the hi-spec reflective coating needed for Silvertown’s requirements (see box), MC-Bauchemie has also helped on a number of other tunnel projects internationally, such as the A7 L’Olleria tunnel in Spain, A100 and A40 tunnels in Germany, Vidovci tunnel in Croatia, and Berzeasca-Caras tunnel in Romania.


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