Road Construction: Suitable Fasteners and Bolts

Types of Bolted Components for Road Construction

The roads we travel daily are characterized by numerous components for which bolts are used during production and installation. Although some elements require more bolts than others, it can be said that all steel elements on a road are assembled using specific screws and bolts.
Among the components with the most bolts, we can include:

• Guardrails: safety devices designed to keep vehicles within the roadway in case of skidding, collisions, or accidents with other vehicles;
  
  
  
• Road barriers: elements designed to absorb part of the energy of the vehicle, thereby limiting the impact on passengers. There are different types: median barriers, side barriers, barriers for structures (e.g., bridges, viaducts, underpasses, etc.), barriers or devices for specific points, and crash attenuators. These components are produced in various materials including concrete and wood with a steel core. The most traditional and well-known are metallic barriers, composed of:
  
  1. Posts: fixed to the ground or bolted to the support;
  
  2. Beams: generally consisting of one or more double or triple wave-shaped plates;
  
  3. Longitudinal elements: arranged parallel to the beam, lower (wheel stoppers) or upper (at the level of structures);
  
  4. Spacers: if present, placed between the beams and posts, functioning to dissipate the energy from light impacts and ensure the beam's uplift during impact, thereby preventing the barrier from being overrun;
  
  5. Diagonal bracings, if present;
  
  6. Connection and anchoring bolts;
  
  7. Supports for anchoring or for driving posts into the ground.
  
  
  
  
• Road signs: devices aimed at indicating a regulation, warning, or direction to all drivers on the road. These elements consist of:
  
  1. Foundation plinth, the base on which the entire structure rests. Generally made of concrete, its dimensions are calculated based on the subsoil (natural ground or fill) on which the pole will be planted. The plinth must therefore ensure stability and perpendicularity over time;
  
  2. Pole, made of hot-dip galvanized steel, circular in section, with well-defined thickness, diameter, and length. The pole must have a specific hole at the lower end, so that it fits perfectly into the plinth, and a plastic cap at the upper end;
  
  3. Sign, the structure indicating the regulation, made of box-section aluminum with a thickness of 25/10 mm. On the front side, a reflective film will be applied, while on the back side, there will be specific grooves or provisions in galvanized steel to fix the sign to the pole with brackets and bolts.
  
  4. Consumables, elements used to achieve a perfect installation of the sign on the pole, resistant to any condition. Among these elements, we include anti-rotation fixing brackets, bolts, washers, and galvanized steel nuts.

Choosing the Right Bolts and Screws

As mentioned previously, technicians and professionals in the field must consider different variables in the construction of practical and safe roads.
Consequently, the fastening elements used will also be chosen based on the needs of each specific road and its components.
In general, the most used fasteners and bolts in this type of construction are:

• Hot-dip galvanized screws and nuts
  
  
• Threaded rods
  
  
• Screws with a round head and square under the head
  
  
• Washers
  
  
• Nuts
  
  
• Tie rods
  
  
• UNI 5588 class 8 nuts
  
  
• UNI 6592 washers
  
  
• ISO 7089 washers

Tests and Quality Certifications for Fasteners and Bolts