Multi-layer work. How Moscow builds roads — from ideation to launch

The Big Circle Line (BCL), new metro stations and the Moscow Central Diameters (MCD), re-start of river taxi service… The Russian capital’s transport is growing at a record pace. However, the municipality does not forget about motorists as in 2023 alone Moscow built over 100 kilometers of roads, including another section of the Moscow High-Speed Diameter (MHSD), to be connected to the Solntsevo — Butovo — Varshavskoye Motorway in 2024, alongside with the launch of the Southern Lateral Road. Building roads in Moscow is not easy, since they have to be laid in densely built-up neighborhoods, and it is critical to uphold asphalt laying processes.

We keep covering Moscow transport construction stages in our series of articles. Previously, we discussed the construction of metro stations, while this time the focus is on the roads. Read below to get to know why architects and historians are involved in road design, what secret ingredient is added to asphalt concrete, what layers the ‘road pie’ consists of, and how roads are tested before starting traffic.

Route to information modeling technologies (IMT). Step I: Creating a project

The history of every facility in the Russian capital, be it a metro station, a bridge, or a road, begins at the Moscow General Planning Research and Project Institute, also known as the Genplan Institute of Moscow. It analyzes how local infrastructure will change in the coming years and determine which motorways may fail to cope with increased traffic. Promising areas of development are included in the master plan, although it does not require details as a decision can only be made taking into account the reality, rather than projected situations. Having discovered a vulnerable section, experts do research to understand whether the roadway can be widened and whether it is possible to create special lanes; if that is not enough, it’s time to build a road.

A road project involves transport and utilities engineers, architects, environmentalists and historians, who build the route so that it does not affect residential quarters or other important buildings, natural areas, and cultural heritage sites, providing sidewalks, bicycle lanes, and ground transport stops. Engineering system layouts are drawn up on a 1: 500 scale. If, for instance, a projected road crosses a water supply system in a neighborhood, they look for ways to bypass it; the engineering networks can be moved to another place, if necessary.

Meanwhile, advanced technology is pivotal for designers as they apply digital modeling to estimate traffic and pedestrian flows, throughput capacity of the entire road, its individual sections, and intersections, each IMT-based motorway project involving creation of a digital information model with physical, functional and other characteristics of all elements. This automates development of documentation, thus helping complete the project on time. After that, the municipality looks for a contractor to engage in the construction processes.

A way to a motorway! Step II: Preparing the site

The road built into the life of the city has been laid, although virtually so far; so, it’s time to make the 3D route a reality. Engineers begin geological surveying to evaluate the terrain, composition and properties of the soil, plus conditions of the soil, air and water bodies in order to think through the construction plan; for example, if the soil is saturated with water, the road will need a stronger sub-basis.

The area will be then cleared and, if necessary, some structures will be dismantled. If they are located on private property, the municipality will initiate a seizure, paying the owners equivalent compensation. And then there is a sketch on a white sheet of paper followed by a surveying control network to define the road boundaries and fences installed on the site with the subgrade strengthened and the embanking.

Asphalt, bitumen and other ‘road pie’ ingredients. Step III: Paving

Asphalt is the upper surface of a road — icing on top of a cake — one can say. Hidden underneath, there are several layers, each having its own function.

The subgrade is covered with geotextiles, in the first place, to prevent ground subsidence and distribute the load during vehicle movement. The next step is the construction of the subbase, which is made of sand and concrete/crushed stone mixture; the crushed stone in the lower layers should be large enough to make the road stable and durable.

Another layer of sand or sand-gravel mixture is placed on top to protect the sub-base against frost, and in wet weather it absorbs and drains water. Additionally, the road will be reinforced with rigid roller compacted concrete with crushed stone mixture acting as a fractionated aggregate.

Now it’s time to pour the ‘glaze.’ Two or three layers of asphalt are distributed on the sub-base; each of them is compacted with a roller. In fact, in addition to asphalt pavers road builders use vibratory rollers, vibration enabling faster and denser paving.

The service life of a road depends, among other things, on the quality of the asphalt surface, which is also referred to as a wearing course, as hundreds and even thousands of cars will drive on it every day. The most common material is asphalt concrete, a mixture of crushed stone, sand, rock dust, and melted asphalt. Unlike lower layers, the upper ones are made of fine crushed stone for the road to get rough, thus enabling reliable traction with tires. There is also a secret ingredient, innovative bitumen, which is crucial for our weather conditions as it prevents the top layers from cracking during temperature fluctuations. In cold weather it becomes softer so as not to burst, and it does not melt longer when it is hot outside. For high-speed roads, builders choose crushed stone-mastic asphalt concrete containing more crushed stone and bitumen. The ‘pie’ will have more layers to be 1.2 meters thick on average, if the road is intended to endure high traffic load.

The pavement type is also of importance; road construction involving hot-laid pavement, which lasts longer, although it is rather thorny to apply. The mixture is heated to +110-+130 °C and laid in dry weather at a temperature not lower than +5 °C to get hardened for about five days. Cold-laid asphalt is less strong, but it can be applied at low temperatures down to -25 °C; so, this is convenient when there is a need to make pothole repairs in winter, the pavement drying within a couple of hours.

A striped road. Step IV: Marking

Bright and durable markings are vital for road safety. It is important that they are visible in the dark and do not need frequent refreshes. In courtyards and parking lots, markings are applied with paint, since traffic is rather low there. It is also used to create temporary markings. Paint should be applied at a temperature of at least +5 °C and a humidity of no more than 85 per cent.

Requirements for markings on high-traffic streets are stricter, in this case roads are marked with hot plastic heated up to +200 °C and applied to the asphalt using special marking machines. And they add glass beads in order to make the lines reflective. Meanwhile, cold plastic is needed when road workers use traffic stencils as they are handy when applying complicated elements that duplicate road signs Caution! Children, School, and Give Way.

Road ‘exam.’ Step V: Testing

The municipality manages road construction at all stages; road materials are sent for laboratory testing, experts also monitor how well road workers follow paving techniques to detect defects and make sure that they are rectified. Road pavement evenness is checked by mobile labs — vehicles with special equipment recording the minutest irregularities and creating a section micro-profile for further analysis and quality evaluation.

Before launching traffic, a road passes an ‘exam’: lab technicians take pavement samples at several sites, using a core sampler, a special equipment for taking samples in asphalt and concrete. In the laboratory, they study them to understand whether the pavement will withstand traffic flows and the vagaries of the weather, predict the risk of shifting road layers and determine the coefficient of tire-asphalt adhesion.

Noise barriers and lighting. Step VI: Landscaping and improvements

New roads unveil new opportunities to move around the city quickly and comfortably, although noise levels increase. So, they install noise barriers along roads and replace window frames in nearby residential buildings with premium soundproof double-glazed windows, the service being free of charge.

New roads also get proper lighting, storm drainage, curbs and road signs, road maintenance providers also tidy up adjacent neighborhoods and arrange pedestrian crossings to finally launch traffic.