Chile’s new urban highway link

Nestling in a valley beside the Andes mountain range, Santiago has a growing population and has suffered from increasingly heavy congestion in recent years, requiring a new urban road link for which safety has been set as a priority for drivers - *iRAP reports
Road Structures / May 2, 2022
Boca sur Escriva de Balaguer : The bored sections of the route are secured using roofbolting and then sprayed with shotcrete
Boca sur Escriva de Balaguer : The bored sections of the route are secured using roofbolting and then sprayed with shotcrete

Chile’s busy capital Santiago is well known for its chronic traffic congestion during peak hours. This is because the city’s population has grown quickly in recent times, resulting in the existing infrastructure struggling to cope with vehicle numbers. Sitting in a valley alongside the Andes mountain range, the city is also known for poor air quality as when the winds drop, pollution can become trapped over Santiago for extended periods. However, a new road link will provide a safer and more dependable transport connection for the city, while also helping to reduce pollution. In addition, this road will establish new technical precedents for Chile as well as the continent as a whole. According to its builders, the Américo Vespucio Oriente I (AVO I) highway in Santiago de Chile will be one of the most modern and innovative road links in Latin America, as well as one of the safest.

Traffic control measures will help to optimise safety for drivers
Traffic control measures will help to optimise safety for drivers

This is one of the largest infrastructure projects in Latin America and the new concession highway will help to move the surface vehicle traffic to the free flow underground road network. The planners claim that the project is providing a solution to the high traffic saturation and poor north-south connectivity in Santiago.

The new highway will help address the city’s chronic pollution problem, firstly by reducing the numbers of vehicles idling with engines running in the frequent traffic jams. Secondly, the air filtration systems for the tunnel sections will also help to lower the quantities of exhaust pollutants reaching the air above the city by trapping contaminants instead. Completing the project will reduce travel times from 40 minutes to 10 minutes and will reduce the frequent jams that occur at present in the centre of the city.

The alignment for the route is just over 9km in length, running across Santiago, and makes the project one of the largest infrastructure works in Latin America. The route of the new Vespucio Oriente Concession runs through the districts of Huechuraba, Recoleta, Vitacura, Las Condes, La Reina y Ñuñoa (from Avda. El Salto to Avda. Príncipe de Gales). Of note too is that the alignment runs under the Mapocho River.

The route transitions from cut and cover tunnel to bored tunnel as it deepens
The route transitions from cut and cover tunnel to bored tunnel as it deepens

To deliver the project, the construction team says it is using advanced technology and innovative methods, in addition to high standards for environmental protection.

By diverting much of the commuter traffic underground, the project will also increase green space on the surface and improve mobility for pedestrians and cyclists.

As part of the AVO project, the Vespucio Park, which extends from Padre Román in the Vitacura district to Avenida Príncipe de Gales in La Reina district, will see its area of green space increased by 15,000m2. This will deliver better facilities for pedestrians and cyclists in the park, as well as providing connections for these vulnerable road users to nearby green spaces, including Parque Metropolitano and Bosque Santiago.

The provision for cyclists will be improved considerably as the pathways in the parks will offer enhanced connections to the wider cycle path network in Santiago. The city’s transport planners are hoping too that this will encourage more people to cycle, particularly for short journeys. This will offer the added benefit of increasing sustainable transport and helping to slow the growth of motor vehicle traffic in Santiago.

Moving much of the crosstown traffic underground will help reduce congestion and pollution for Santiago
Moving much of the crosstown traffic underground will help reduce congestion and pollution for Santiago

While Chile is by no means the worst offender with regard to road casualties in Latin America, improved safety has been set as a priority for the development of the project. According to Chile's National Traffic Safety Commission (Conaset), 1,479 road deaths were reported in the country in 2020. While this was a lower level of casualties than many of its neighbours, it has been recognised that the new highway could help to cut Santiago’s annual rate of crashes and to reduce the numbers of serious injuries and deaths on the city’s roads.

To ensure the new route would be engineered to provide sufficient levels of safety for its users, SCAVO engaged iRAP to Star Rate much of the proposed designs. As a result, the designs for the Américo Vespucio Oriente I (AVO I) concession have been assessed using the iRAP Star Rating methodology. The aim of this work was to assess the level of safety and recommend a Safer Roads Investment Plan, while the goal was to achieve a minimum 3-star rating for safety before construction commenced.

The United Nations Sustainable Development Goals seek to halve the number of deaths worldwide, in part through the adoption and application of the iRAP Star Rating methodology.

ble role for the underground works
ble role for the underground works

SCAVO general manager Luis Eusebio commented, “AVO I is one of the most important public infrastructure initiatives underway in the country.

“Not only is it large in magnitude, it also combines a series of construction methods: overpass, cut and cover tunnel and bored tunnel. Protecting road users is a priority and achieving 3-star or better allows us to have a benchmark against which to measure performance on our concessions in relation to international safety standards," he said.

“Having this evidence base to measure the safety of the existing design and investment plan and quantify the cost of recommended improvements allows us to plan the implementation of countermeasure recommendations to provide safe travel for our users,” Eusebio added.

The mainline cross-section of the concession is comprised of three free flow lanes for each carriageway, while the project is divided two main sectors.

Access equipment is being used to assist with the meshing work prior to shotcreting the bored stretches
Access equipment is being used to assist with the meshing work prior to shotcreting the bored stretches

Sector 1 extends from the Avenida El Salto to the Centennial Bridge. This section of the project includes the construction of a main overpass and a secondary overpass, a three lane bored tunnel under Cerro San Cristóbal and another under the Mapocho River, as well as improvements to the existing surface road on the descent from La Pirámide.

Sector 2 runs from the Centennial Bridge in the north to Avenida Príncipe de Gales in the south and is comprised of dual three-lane carriageway tunnels. The plans call for these tunnels to be built using a combination of both bored and cut and cover techniques.

The tunnel design is innovative, with some stretches, such as the Tunel Hibrido, featuring dual decks. Three lanes are available for drivers on one deck, with another triple lane deck underneath carrying traffic in the opposite direction.

The iRAP project manager Morgan Fletcher commented, "Engineering safety at the design phase is a smart investment of time and money, and essential for reducing road trauma.

Conventional excavation methods have been used in the tunnelling work for the project
Conventional excavation methods have been used in the tunnelling work for the project

“Being able to identify high-risk road sections and alter the design to improve safety before construction translates to reduced crashes, fatalities and injuries. It can be incredibly expensive, and sometimes cost-prohibitive to change road infrastructure once its built, but a tweak of the design is very easy. The client can immediately see how many lives a change will save and prioritise investment accordingly,” Fletcher added.

“Where a design change isn’t logistically feasible, reducing speeds is an effective solution to improving safety,” he said.

The iRAP Star Rating evaluates a range of characteristics of the road infrastructure and how they influence the probability and severity of traffic crashes. A 1-star road is the least safe, whilst a 5-star road is the safest.

The iRAP Star Rating of the AVO I concession design provided a simple and objective measure of the level of road safety that could be built-in for the design.

Conventional shotcreting equipment is being used
Conventional shotcreting equipment is being used

Fletcher said speed is a key element of the Safe System and the probability of being involved in a serious or fatal crash increases considerably, even with small increases in vehicle speeds. “Research suggests just a 5% increase in average speed leads to a 20% increase in the likelihood of injury in the event of a crash, and a 20% increase in average speed leads to a 20% increase in the likelihood of injury in the event of a crash, and a 20% increase in the probability of a fatality.

“It is important that drivers adopt a safe speed for the road environment, the traffic mix and the fleet involved. Speed limits must be appropriate for the road design.

“Given the difficulty of implementing improvements in the AVO I underground, speed control is the best alternative to guarantee a 3-star or better journey for its road users,” Fletcher said.

The route is designed for use by motor vehicles, so pedestrians and cyclists were not considered during the safety evaluation. Meanwhile, the number of motorcycles in use in Santiago is comparatively small, so these vehicle types were not considered during the safety analysis of the route.

Preliminary results showed that for vehicle occupants, 100% of the assessed road network obtained the recommended target of 3-star or better. The iRAP assessment considered over 90 proven safety treatments that could help to deliver a Safer Road Investment Plan (SRIP) and improve the design's Star Rating. Using the evaluation process, iRAP was also able to recommend design improvements to reduce the rated of crashes and the casualty rate.

 Tunnels will divert traffic away from the surface
Tunnels will divert traffic away from the surface

Two scenarios were considered. One proposal for the AVO I Safer Road Investment Plan would have cost $220,000 to install 13.9km of shoulder rumble strips on high-risk sections. Research suggested this would prevent around 29 deaths and serious injuries over 20 years, with an overall cost-benefit ratio of $14 for every $1 spent. Including shoulder rumble strips would result in almost 60% of the assessed network achieving a rating of 4- and 5-stars.

For vehicle occupants, the comparison of the road length rating 3-star or better between the base design and the improved Scenario 1 design shows no apparent change; however, analysing the change in road length rated 4-star or better shows an improvement from 42% to 59.6% between the base design and the improved design incorporating recommended infrastructure improvements .

Much of the route runs through stretches of bored tunnels, cut and cover tunnels or overpasses and widening these sections to improve safety would have been prohibitively costly.

However, a more practical and cost-effective solution was to implement speed control measures and eliminate sharp curves. The evaluation process showed that this would decrease risks for drivers while improving the Star Rating of the entire corridor at no additional cost.

Based on modelling, using speed management systems would ensure that all of the assessed section of the highway would feature a 4-star safety rating (or better) for vehicle occupants.

*This report has been produced using information provided by iRAP


The project is being handled by a concession firm, Sociedad Concesionaria Vespucio Oriente, formed between ALEATICA and SACYR Concesiones Chile. This holding company was established to handle the contract for the Avenida El Salto - Príncipe de Gales Section of the Américo Vespucio Oriente Concession. The project forms part of the wider Santiago Urban Transportation System improvement programme promoted by the Chilean Government, through the Ministry of Public Works.

The AVO I Concession Project runs through six suburbs from Avenida El Salto in the north to Avenida Príncipe de Gales in the south. The new AVO I and AVO II (Príncipe de Gales – Los Presidentes) are providing the missing links in the Américo Vespucio road ring that encircles much of Santiago’s metropolitan area.


The Chilean Government has opened the tender process into the concession package for the Orbital Santiago Sur motorway. Construction of the link is expected to cost US$500 million. The concession will include operation of the route for a period of 36 years and the schedule will see the package being awarded before the end of 2022.

In addition, the tender process is open for the important Route 68 highway upgrade project, which connects Santiago, with the key coastal cities of Valparaiso and Vina del Mar. Upgrading the highway would help boost transport efficiency between Santiago and the two port cities.

The 105km stretch of highway carries a heavy traffic loading, with around 37.5 million vehicles having used the route between the start of January and the end of November in 2021. The route does carry considerable numbers of heavy vehicles carrying goods to and from the two ports.

Improving the route would help deliver a major boost for Chile’s economy. The work is expected to cost in the region of $1.2 billion to carry out.

Safer roads reduce economic as well as human costs | Source: OECD (2016)
Safer roads reduce economic as well as human costs | Source: OECD (2016)