Commonwealth Avenue (Quezon City)

Commonwealth Avenue, formerly known as Don Mariano Marcos Avenue, is a 12.4 km highway located in Quezon City, Philippines. It spans from six to eighteen lanes, making it the widest road in the country. The avenue is one of the major roads in Metro Manila and is designated as part of Radial Road 7 (R-7) of the older Manila arterial road system and National Route 170 (N170) of the Philippine highway network.

Commonwealth Avenue starts at Elliptical Road, which encircles the Quezon Memorial Circle, and passes through the areas of Philcoa, Tandang Sora, Balara, Batasan Hills, Fairview, and ends at Quirino Highway in the Novaliches area.

Being located in Quezon City, which is among several cities in Metro Manila with a high incidence of road accidents, the avenue has a high accident rate, particularly due to overspeeding, earning it the nickname "Killer Highway". A speed limit of 60 kph is being enforced to reduce accidents on the avenue.

Route description
Commonwealth Avenue follows a curving route from Elliptical Road to Quirino Highway. It is divided into two portions, eighteen-lane main segment formerly named Don Mariano Marcos Avenue and the six-to eight-lane Fairview Avenue. The Fairview Rotonda, a roundabout at the intersection with Doña Carmen Street at the barangay boundary of Commonwealth and Fairview, marks the division between these two segments.

The main segment, formerly named Don Mariano Marcos Avenue (after Mariano Marcos, the father of former Philippine President Ferdinand Marcos), stretches south of Fairview Rotonda. It features partial control of access with interchanges and U-turn slots replacing at-grade intersections, and pedestrian crossings placed on overpasses (footbridges). This segment has 18 lanes, with 9 lanes per direction, excluding dedicated lanes for motorcycles, buses, jeepneys, and bicycles. An exclusive motorcycle lane, implemented in March 2023, restricts motorcycles to the third lane except when entering or exiting the highway.

On the other hand, Fairview Avenue, north of Fairview Rotonda, has 6 to 8 lanes with most intersections at-grade, usually with traffic lights.

Being located in Quezon City, which has a high number of road accidents, Commonwealth Avenue has a high incidence of accidents along with Quezon Avenue. The number of accidents in the avenue have lend its known nickname, the "Killer Highway".

Bicycle lanes
The outermost lanes of Commonwealth Avenue from Quezon Memorial Circle to Doña Carmen Avenue are designated as bi-directional bike lanes with plastic barriers and 0.6 m buffer zones on both sides as part of Quezon City's bike lane network. A portion of the bike lane also uses concrete plant boxes instead of plastic barriers, with the city planning to replace plastic barriers with plant boxes in the near future.

Prior to the establishment of the city bike lane network during the COVID-19 pandemic, a bi-directional grade-separated bike lane was established by the MMDA in 2012 along a 2.92 km segment of the highway from University Avenue to Tandang Sora.

MRT Line 7
The Metro Rail Transit Line 7 (MRT 7), which will connect with the Metro Rail Transit Line 3 at North Triangle Common Station, began construction in 2016. Most of the alignment of the MRT 7 will follow the Center island of Commonwealth Avenue up to Regalado Highway.

History
The avenue's origins can be traced back to a segment of a road that connected the proposed site of the National Capitol in what is now Elliptical Road to the University of the Philippines Diliman campus and comprises what is now University Avenue. The original 1941 Frost Plan envisioned a road network connecting the proposed Capitol to the proposed Philippine Military Academy (PMA) through barrio Balara. However, by 1949, the revised Frost Plan shifted focus to constructing a road directly connecting Quezon Memorial Circle, which replaced the original Capitol site that was scrapped after World War II, to the new National Government Center (location of the present-day Batasang Pambansa Complex) at Constitution Hill, which replaced the proposed PMA site.

Originally named Don Mariano Marcos Avenue, the avenue was eventually constructed in the late 1960s as a two-lane highway. Quezon City was then the capital of the Philippines and embassies were to be put up on the stretch of highway. Because the country's capital was moved back to Manila in 1976, other establishments were put up instead. Don Mariano Marcos Avenue was later renamed into two parts, Commonwealth Avenue and Quezon Avenue. Later, Commonwealth Avenue regained the eight-lane Fairview Avenue, which used to end near Jordan Plains Subdivision in Novaliches.

In the 1980s, the road was widened into a six-lane highway. During the late 1990s and early 2000s, the avenue was prone to heavy traffic and accidents due to the increase in number of public transportation vehicles plying the highway, and sidewalk vendors crowding onto the road. In the late 2000s, the Metropolitan Manila Development Authority (MMDA) cleared the sidewalk vendors, especially in the Tandang Sora area, which was prone to heavy rush hour traffic. Fairview Avenue uses stoplights and center island splittings at its intersections, while Don Mariano Marcos Avenue uses interchanges at its intersections.

The avenue is 18 lanes at its widest, and is the widest road in the Philippines, beating the old record set by EDSA.

Linking to Quirino Highway
On October 1, 2009, Quezon City Mayor Feliciano Belmonte Jr. announced his 15-year-old plan to link Commonwealth Avenue and Quirino Highway at the cost of ₱20 million to ₱140 million, which would be adjacent to the Zabarte Road. The project was completed in May 2011 and is already operational.

Speed limit implementation
In May 2011, a 60 kph speed limit was implemented on Commonwealth Avenue following the death of Lourdes Estella-Simbulan, a journalist, in a road accident on the avenue. During the first week of its implementation, 120 violators were apprehended after speeds of over 60 kph were recorded through speed guns.

Renaming proposals
During the 16th Congress, Representatives Miro Quimbo (Marikina–2nd) and Erlinda Santiago (SAGIP Partylist) filed separate House bills to rename the avenue into Eraño G. Manalo Avenue, after Eraño Manalo, the second Executive Minister of the Iglesia ni Cristo, which has a central temple along the avenue. Meanwhile, the Makabayan bloc wanted to rename the avenue after former Filipino senator Lorenzo Tañada.