An empty freeway intersection is seen two days before Earth Day, after Los Angeles’ stay-at-home order caused a drop in pollution, as the global outbreak of the coronavirus disease (COVID-19) continues, in Pasadena, near Los Angeles, California, U.S., April 20, 2020. REUTERS/Lucy Nicholson REFILE - CORRECTING LOCATION 

An empty freeway intersection is seen two days before Earth Day, after Los Angeles’ stay-at-home order caused a drop in pollution, as the global outbreak of the coronavirus disease (COVID-19) continues, in Pasadena, near Los Angeles, California, U.S., April 20, 2020. REUTERS/Lucy Nicholson REFILE - CORRECTING LOCATION 

An empty freeway intersection is seen two days before Earth Day, after Los Angeles’ stay-at-home order caused a drop in pollution, as the global outbreak of the coronavirus disease (COVID-19) continues, in Pasadena, near Los Angeles, California, U.S., April 20, 2020. REUTERS/Lucy Nicholson REFILE - CORRECTING LOCATION TPX IMAGES OF THE DAY 

An empty freeway intersection is seen two days before Earth Day, after Los Angeles’ stay-at-home order caused a drop in pollution, as the global outbreak of the coronavirus disease (COVID-19) continues, in Pasadena, near Los Angeles, California, U.S., April 20, 2020. REUTERS/Lucy Nicholson REFILE - CORRECTING LOCATION 

An empty freeway intersection is seen two days before Earth Day, after Los Angeles’ stay-at-home order caused a drop in pollution, as the global outbreak of the coronavirus disease (COVID-19) continues, in Pasadena, near Los Angeles, California, U.S., April 20, 2020. REUTERS/Lucy Nicholson REFILE - CORRECTING LOCATION 

An empty freeway intersection is seen two days before Earth Day, after Los Angeles’ stay-at-home order caused a drop in pollution, as the global outbreak of the coronavirus disease (COVID-19) continues, in Pasadena, near Los Angeles, California, U.S., April 20, 2020. REUTERS/Lucy Nicholson REFILE - CORRECTING LOCATION 

An empty freeway intersection is seen two days before Earth Day, after Los Angeles’ stay-at-home order caused a drop in pollution, as the global outbreak of the coronavirus disease (COVID-19) continues, in Pasadena, near Los Angeles, California, U.S., April 20, 2020. REUTERS/Lucy Nicholson REFILE - CORRECTING LOCATION 

General view of the Port of Dover in Kent, as the spread of the coronavirus disease (COVID-19) continues, Dover, Britain, April 18, 2020. REUTERS/Matthew Childs 

A giraffe walks near the elevated railway line that allows movement of animals below the Standard Gauge Railway (SGR) line linking Nairobi and Naivasha inside the Nairobi national park in Nairobi, Kenya October 16, 2019. REUTERS/Njeri Mwangi TPX IMAGES OF THE DAY 

Giraffes walk near the elevated railway line that allows movement of animals below the Standard Gauge Railway line linking Nairobi and Naivasha inside the Nairobi national park in Nairobi, Kenya October 16, 2019. REUTERS/Njeri Mwangi 

Giraffes walk as a motorist drives near the elevated railway line that allows movement of animals below the Standard Gauge Railway (SGR) line linking Nairobi and Naivasha inside the Nairobi national park in Nairobi, Kenya October 16, 2019. REUTERS/Njeri Mwangi 

A giraffe walks near the elevated railway line that allows movement of animals below the Standard Gauge Railway (SGR) line linking Nairobi and Naivasha inside the Nairobi national park in Nairobi, Kenya October 16, 2019. REUTERS/Njeri Mwangi 

A group of impala graze near the elevated railway line that allows movement of animals below the Standard Gauge Railway (SGR) line linking Nairobi and Naivasha inside the Nairobi national park in Nairobi, Kenya October 16, 2019. REUTERS/Njeri Mwangi 

A general view shows the Taminaschlucht gorge near Bad Ragaz, Switzerland June 10, 2019. Picture taken June 10, 2019. REUTERS/Arnd Wiegmann 

A general view shows the Taminaschlucht gorge near Bad Ragaz, Switzerland June 10, 2019. Picture taken June 10, 2019. Picture taken June 10, 2019. REUTERS/Arnd Wiegmann 

A view of the column of a viaduct on BR-020 road, which was compromised, after it was damaged by a bomb in Fortaleza, Brazil January 7, 2019. REUTERS/Paulo Whitaker 

A general view of a viaduct on BR-020 road, with the structure compromised, after one of the columns was damaged by a bomb in Fortaleza, Brazil January 7, 2019. REUTERS/Paulo Whitaker 

Street lights are seen between viaducts during dusk in Bogota city, Colombia, June 14, 2018. REUTERS/Andres Stapff 

A member of Brazil's Movimento dos Sem-Teto (Roofless Movement), comforts her daughter under a barrack on the Cha viaduct, in front of the city hall of Sao Paulo September 16, 2015. The movement is setting up camp to protest against the eviction from buildings occupied by the families. REUTERS/Nacho Doce

Members of Brazil's Movimento dos Sem-Teto (Roofless Movement), sit under a barrack on the Cha viaduct, in front of the city hall of Sao Paulo September 16, 2015. The movement is setting up camp to protest against the eviction from buildings occupied by the families. REUTERS/Nacho Doce

Members of Brazil's Movimento dos Sem-Teto (Roofless Movement), set up camp on the Cha viaduct, in front of the city hall of Sao Paulo September 16, 2015. The movement is setting up camp to protest against the eviction from buildings occupied by the families. REUTERS/Nacho Doce

Athletes run past Joa viaduct during the Rio Marathon in Rio de Janeiro, Brazil, July 26, 2015. REUTERS/Sergio Moraes 

People pay tribute to the coffins of victims of a coach crash at the end of the funeral service at the Monteruscello Palasport near Pozzuoli July 30, 2013. Thousands of people packed into a sports hall in the southern town of Pozzuoli on Tuesday to commemorate 38 people who died when a coach plunged 25 metres (80 ft) off a motorway viaduct in one of the worst road accidents in Italian history. REUTERS/Ciro De Luca (ITALY - Tags: DISASTER TRANSPORT) 

A relative sits next to the coffins of victims of a coach crash during the funeral service at the Monteruscello Palasport near Pozzuoli July 30, 2013. Thousands of people packed into a sports hall in the southern town of Pozzuoli on Tuesday to commemorate 38 people who died when a coach plunged 25 metres (80 ft) off a motorway viaduct in one of the worst road accidents in Italian history. REUTERS/Ciro De Luca (ITALY - Tags: DISASTER TRANSPORT) 

A woman cries next to the coffins of victims of a coach crash during the funeral service at the Monteruscello Palasport near Pozzuoli July 30, 2013. Thousands of people packed into a sports hall in the southern town of Pozzuoli on Tuesday to commemorate 38 people who died when a coach plunged 25 metres (80 ft) off a motorway viaduct in one of the worst road accidents in Italian history. REUTERS/Ciro De Luca (ITALY - Tags: DISASTER TRANSPORT) 

Relatives sit next to the coffins of victims of a coach crash during the funeral service at the Monteruscello Palasport near Pozzuoli July 30, 2013. Thousands of people packed into a sports hall in the southern town of Pozzuoli on Tuesday to commemorate 38 people who died when a coach plunged 25 metres (80 ft) off a motorway viaduct in one of the worst road accidents in Italian history. REUTERS/Ciro De Luca (ITALY - Tags: DISASTER TRANSPORT) 

People touch the coffin of one of the victims of a coach crash at the end of the funeral service at the Monteruscello Palasport near Pozzuoli July 30, 2013. Thousands of people packed into a sports hall in the southern town of Pozzuoli on Tuesday to commemorate 38 people who died when a coach plunged 25 metres (80 ft) off a motorway viaduct in one of the worst road accidents in Italian history. REUTERS/Ciro De Luca (ITALY - Tags: DISASTER TRANSPORT) 

People pay tribute to the coffins of victims of a coach crash at the end of the funeral service at the Monteruscello Palasport near Pozzuoli July 30, 2013. Thousands of people packed into a sports hall in the southern town of Pozzuoli on Tuesday to commemorate 38 people who died when a coach plunged 25 metres (80 ft) off a motorway viaduct in one of the worst road accidents in Italian history. REUTERS/Ciro De Luca (ITALY - Tags: DISASTER TRANSPORT) 

Relatives sit next to the coffins of victims of a coach crash during the funeral service at the Monteruscello Palasport near Pozzuoli July 30, 2013. Thousands of people packed into a sports hall in the southern town of Pozzuoli on Tuesday to commemorate 38 people who died when a coach plunged 25 metres (80 ft) off a motorway viaduct in one of the worst road accidents in Italian history. REUTERS/Ciro De Luca (ITALY - Tags: DISASTER TRANSPORT) 

People touch the coffin of one of the victims of a coach crash at the end of the funeral service at the Monteruscello Palasport near Pozzuoli July 30, 2013. Thousands of people packed into a sports hall in the southern town of Pozzuoli on Tuesday to commemorate 38 people who died when a coach plunged 25 metres (80 ft) off a motorway viaduct in one of the worst road accidents in Italian history. REUTERS/Ciro De Luca (ITALY - Tags: DISASTER TRANSPORT) 

People pay tribute to the coffins of victims of a coach crash at the end of the funeral service at the Monteruscello Palasport near Pozzuoli July 30, 2013. Thousands of people packed into a sports hall in the southern town of Pozzuoli on Tuesday to commemorate 38 people who died when a coach plunged 25 metres (80 ft) off a motorway viaduct in one of the worst road accidents in Italian history. REUTERS/Ciro De Luca (ITALY - Tags: DISASTER TRANSPORT TPX IMAGES OF THE DAY) 

People pay tribute to a coffin of one of the victims of a coach crash at the end of the funeral service at the Monteruscello Palasport near Pozzuoli July 30, 2013. Thousands of people packed into a sports hall in the southern town of Pozzuoli on Tuesday to commemorate 38 people who died when a coach plunged 25 metres (80 ft) off a motorway viaduct in one of the worst road accidents in Italian history. REUTERS/Ciro De Luca (ITALY - Tags: DISASTER TRANSPORT) 

Relatives sit next to the coffins of victims of a coach crash during the funeral service at the Monteruscello Palasport near Pozzuoli July 30, 2013. Thousands of people packed into a sports hall in the southern town of Pozzuoli on Tuesday to commemorate 38 people who died when a coach plunged 25 metres (80 ft) off a motorway viaduct in one of the worst road accidents in Italian history. REUTERS/Ciro De Luca (ITALY - Tags: DISASTER TRANSPORT) 

Italy's Prime Minister Enrico Letta (C) reacts as he attends the funeral service of victims of a coach crash at the Monteruscello Palasport near Pozzuoli July 30, 2013. Thousands of people packed into a sports hall in the southern town of Pozzuoli on Tuesday to commemorate 38 people who died when a coach plunged 25 metres (80 ft) off a motorway viaduct in one of the worst road accidents in Italian history. Letta was among an estimated 4,000 mourners at the service during a day of national mourning called after the accident. REUTERS/Ciro De Luca (ITALY - Tags: DISASTER TRANSPORT POLITICS) 

A man sits next to the coffins of victims of a coach crash during the funeral service at the Monteruscello Palasport near Pozzuoli July 30, 2013. Thousands of people packed into a sports hall in the southern town of Pozzuoli on Tuesday to commemorate 38 people who died when a coach plunged 25 metres (80 ft) off a motorway viaduct in one of the worst road accidents in Italian history. REUTERS/Ciro De Luca (ITALY - Tags: DISASTER TRANSPORT) 

People mourn next to the coffins of victims of a coach crash during the funeral service at the Monteruscello Palasport near Pozzuoli July 30, 2013. Thousands of people packed into a sports hall in the southern town of Pozzuoli on Tuesday to commemorate 38 people who died when a coach plunged 25 metres (80 ft) off a motorway viaduct in one of the worst road accidents in Italian history. REUTERS/Ciro De Luca (ITALY - Tags: DISASTER TRANSPORT) 

Women cry next to the coffins of victims of a coach crash during the funeral service at the Monteruscello Palasport near Pozzuoli July 30, 2013. Thousands of people packed into a sports hall in the southern town of Pozzuoli on Tuesday to commemorate 38 people who died when a coach plunged 25 metres (80 ft) off a motorway viaduct in one of the worst road accidents in Italian history. REUTERS/Ciro De Luca (ITALY - Tags: DISASTER TRANSPORT) 

A woman cries next to the coffins of victims of a coach crash during the funeral service at the Monteruscello Palasport near Pozzuoli July 30, 2013. Thousands of people packed into a sports hall in the southern town of Pozzuoli on Tuesday to commemorate 38 people who died when a coach plunged 25 metres (80 ft) off a motorway viaduct in one of the worst road accidents in Italian history. REUTERS/Ciro De Luca (ITALY - Tags: DISASTER TRANSPORT TPX IMAGES OF THE DAY) 

Relatives of victims of a coach crash carry a coffin, outside a gym where all the bodies were gathered to be claimed, in Monteforte Irpino near Avellino July 29, 2013. Thirty-eight people were killed and 18 injured when the bus plunged 25 metres (80 ft) off a viaduct in southern Italy, in the second major transport disaster in southern Europe in less than a week. REUTERS/Ciro De Luca (ITALY - Tags: DISASTER TRANSPORT) 

A relative of a victim of a coach crash reacts on the coffin, outside a gym where all the bodies were gathered to be claimed, in Monteforte Irpino near Avellino July 29, 2013. Thirty-eight people were killed and 18 injured when the bus plunged 25 metres (80 ft) off a viaduct in southern Italy, in the second major transport disaster in southern Europe in less than a week. REUTERS/Ciro De Luca (ITALY - Tags: DISASTER TRANSPORT TPX IMAGES OF THE DAY) 

Relatives of the victims of a coach crash react as they stand outside a gym where all the bodies were gathered to be claimed, in Monteforte Irpino near Avellino July 29, 2013. Thirty-nine people were killed and around 10 injured when a bus plunged off a viaduct in southern Italy in what Prime Minister Enrico Letta described on Monday as a huge tragedy. REUTERS/Ciro De Luca (ITALY - Tags: DISASTER TRANSPORT) 

A worker stands on the wreckage of a coach which plunged off a viaduct near the southern town of Avellino July 29, 2013. Thirty-nine people were killed and around 10 injured when the bus plunged off a viaduct in southern Italy in what Prime Minister Enrico Letta described on Monday as a huge tragedy. Initial reports suggested that the coach was travelling at speed and had hit four or five cars before crashing over the roadside barriers on a stretch of road near Monteforte Irpino, east of Naples, on Sunday night. There were around 50 people on board, including many children. REUTERS/Ciro De Luca (ITALY - Tags: DISASTER TRANSPORT) 

A firefighter works on the wreckage of a coach which plunged off a viaduct near the southern town of Avellino July 29, 2013. Thirty-nine people were killed and around 10 injured when the bus plunged off a viaduct in southern Italy in what Prime Minister Enrico Letta described on Monday as a huge tragedy. Initial reports suggested that the coach was travelling at speed and had hit four or five cars before crashing over the roadside barriers on a stretch of road near Monteforte Irpino, east of Naples, on Sunday night. There were around 50 people on board, including many children. REUTERS/Ciro De Luca (ITALY - Tags: DISASTER TRANSPORT) 

Relatives of the victims of a coach crash wait outside a gym where all the bodies were collected to be recognized in Monteforte Irpino near Avellino July 29, 2013. Thirty-nine people were killed and around 10 injured when the bus plunged off a viaduct in southern Italy in what Prime Minister Enrico Letta described on Monday as a huge tragedy. Initial reports suggested that the coach was travelling at speed and had hit four or five cars before crashing over the roadside barriers on a stretch of road near Monteforte Irpino, east of Naples, on Sunday night. There were around 50 people on board, including many children. REUTERS/Ciro De Luca (ITALY - Tags: DISASTER TRANSPORT) 

The wreckage of a coach which plunged off a viaduct is loaded onto a trailer near the southern town of Avellino July 29, 2013. Thirty-nine people were killed and around 10 injured when the bus plunged off a viaduct in southern Italy in what Prime Minister Enrico Letta described on Monday as a huge tragedy. Initial reports suggested that the coach was travelling at speed and had hit four or five cars before crashing over the roadside barriers on a stretch of road near Monteforte Irpino, east of Naples, on Sunday night. There were around 50 people on board, including many children. REUTERS/Ciro De Luca (ITALY - Tags: DISASTER TRANSPORT) 

A crane removes the wreckage of a coach which plunged off a viaduct near the southern town of Avellino July 29, 2013. Thirty-nine people were killed and around 10 injured when the bus plunged off a viaduct in southern Italy in what Prime Minister Enrico Letta described on Monday as a huge tragedy. REUTERS/Ciro De Luca (ITALY - Tags: DISASTER TRANSPORT TPX IMAGES OF THE DAY) 

Relatives of the victims of a coach crash stand outside a gym where all the bodies were collected to be recognized in Monteforte Irpino near Avellino July 29, 2013. Thirty-nine people were killed and around 10 injured when the bus plunged off a viaduct in southern Italy in what Prime Minister Enrico Letta described on Monday as a huge tragedy. Initial reports suggested that the coach was travelling at speed and had hit four or five cars before crashing over the roadside barriers on a stretch of road near Monteforte Irpino, east of Naples, on Sunday night. There were around 50 people on board, including many children. REUTERS/Ciro De Luca (ITALY - Tags: DISASTER TRANSPORT) 

A crucifix is seen as a policeman stands next to the wreckage of a coach crash near the southern town of Avellino July 29, 2013. Thirty-nine people were killed and around 10 injured when the bus plunged off a viaduct in southern Italy in what Prime Minister Enrico Letta described on Monday as a huge tragedy. REUTERS/Ciro De Luca (ITALY - Tags: DISASTER TRANSPORT) 

Vincenzo Figliolia (L), the mayor of Pozzuoli where victims of a coach crash came from, cries as he leaves a gym where all the bodies were collected to be recognized in Monteforte Irpino, near Avellino July 29, 2013. Thirty-nine people were killed and around 10 injured when the bus plunged off a viaduct in southern Italy in what Prime Minister Enrico Letta described on Monday as a huge tragedy. REUTERS/Ciro De Luca (ITALY - Tags: DISASTER TRANSPORT POLITICS TPX IMAGES OF THE DAY) 

A firefighter walks at the site of a coach crash near the southern town of Avellino July 29, 2013. Thirty-nine people were killed and around 10 injured when the bus plunged off a viaduct in southern Italy in what Prime Minister Enrico Letta described on Monday as a huge tragedy. Initial reports suggested that the coach was travelling at speed and had hit four or five cars before crashing over the roadside barriers on a stretch of road near Monteforte Irpino, east of Naples, on Sunday night. There were around 50 people on board, including many children. REUTERS/Ciro De Luca (ITALY - Tags: DISASTER TRANSPORT TPX IMAGES OF THE DAY) 

A book and some food are seen where a coach crashed after plunging off a viaduct near the southern town of Avellino July 29, 2013. Thirty-nine people were killed and around 10 injured when the bus plunged off a viaduct in southern Italy in what Prime Minister Enrico Letta described on Monday as a huge tragedy. Initial reports suggested that the coach was travelling at speed and had hit four or five cars before crashing over the roadside barriers on a stretch of road near Monteforte Irpino, east of Naples, on Sunday night. There were around 50 people on board, including many children. REUTERS/Ciro De Luca (ITALY - Tags: DISASTER TRANSPORT) 

A policeman stands at the site of a coach crash near the southern town of Avellino July 29, 2013. Thirty-nine people were killed and around 10 injured when the bus plunged off a viaduct in southern Italy in what Prime Minister Enrico Letta described on Monday as a huge tragedy. Initial reports suggested that the coach was travelling at speed and had hit four or five cars before crashing over the roadside barriers on a stretch of road near Monteforte Irpino, east of Naples, on Sunday night. There were around 50 people on board, including many children. REUTERS/Ciro De Luca (ITALY - Tags: DISASTER TRANSPORT) 

A firefighter stands next to a section of a viaduct broken by a coach which plunged off, near the southern town of Avellino July 29, 2013. Thirty-nine people were killed and around 10 injured when the bus plunged off a viaduct in southern Italy in what Prime Minister Enrico Letta described on Monday as a huge tragedy. Initial reports suggested that the coach was travelling at speed and had hit four or five cars before crashing over the roadside barriers on a stretch of road near Monteforte Irpino, east of Naples, on Sunday night. There were around 50 people on board, including many children. REUTERS/Ciro De Luca (ITALY - Tags: DISASTER TRANSPORT TPX IMAGES OF THE DAY) 

The site of a coach crash is pictured in the southern town of Avellino July 29, 2013. Thirty-nine people were killed and around 10 injured when the bus plunged off a viaduct in southern Italy in what Prime Minister Enrico Letta described on Monday as a huge tragedy. Initial reports suggested that the coach was travelling at speed and had hit four or five cars before crashing over the roadside barriers on a stretch of road near Monteforte Irpino, east of Naples, on Sunday night. There were around 50 people on board, including many children. REUTERS/Ciro De Luca (ITALY - Tags: DISASTER TRANSPORT) 

A section of the viaduct broken by a coach after it plunged off is seen near the southern town of Avellino July 29, 2013. Thirty-nine people were killed and around 10 injured when a bus plunged off a viaduct in southern Italy in what Prime Minister Enrico Letta described on Monday as a huge tragedy. Initial reports suggested that the coach was travelling at speed and had hit four or five cars before crashing over the roadside barriers on a stretch of road near Monteforte Irpino, east of Naples, on Sunday night. There were around 50 people on board, including many children. REUTERS/Ciro De Luca (ITALY - Tags: DISASTER) 

The viaduct where a coach plunged off is seen near the southern town of Avellino July 29, 2013. Thirty-nine people were killed and around 10 injured when a bus plunged off a viaduct in southern Italy in what Prime Minister Enrico Letta described on Monday as a huge tragedy. Initial reports suggested that the coach was travelling at speed and had hit four or five cars before crashing over the roadside barriers on a stretch of road near Monteforte Irpino, east of Naples, on Sunday night. There were around 50 people on board, including many children. REUTERS/Ciro De Luca (ITALY - Tags: DISASTER) 

People gather at the site where a coach plunged off a viaduct near the southern town of Avellino July 29, 2013. Thirty-nine people were killed and around 10 injured when a bus plunged off a viaduct in southern Italy in what Prime Minister Enrico Letta described on Monday as a huge tragedy. Initial reports suggested that the coach was travelling at speed and had hit four or five cars before crashing over the roadside barriers on a stretch of road near Monteforte Irpino, east of Naples, on Sunday night. There were around 50 people on board, including many children. REUTERS/Ciro De Luca (ITALY - Tags: DISASTER) 

People gather at the site where a coach plunged off a viaduct near the southern town of Avellino July 29, 2013. Thirty-nine people were killed and around 10 injured when a bus plunged off a viaduct in southern Italy in what Prime Minister Enrico Letta described on Monday as a huge tragedy. Initial reports suggested that the coach was travelling at speed and had hit four or five cars before crashing over the roadside barriers on a stretch of road near Monteforte Irpino, east of Naples, on Sunday night. There were around 50 people on board, including many children. REUTERS/Ciro De Luca (ITALY - Tags: DISASTER) 

A bunch of flowers and a crucifix is placed near the site where a coach crashed after plunging off a viaduct near the southern town of Avellino July 29, 2013. Thirty-nine people were killed and around 10 injured when a bus plunged off a viaduct in southern Italy in what Prime Minister Enrico Letta described on Monday as a huge tragedy. Initial reports suggested that the coach was travelling at speed and had hit four or five cars before crashing over the roadside barriers on a stretch of road near Monteforte Irpino, east of Naples, on Sunday night. There were around 50 people on board, including many children. REUTERS/Ciro De Luca (ITALY - Tags: DISASTER)