Posts by Cristhian Barajas

Replica of the ancient Lepidodendrons or giant clubmosses at the Evolution Garden. Photo: Creative Commons

Replica of the ancient Lepidodendrons or giant clubmosses at the Evolution Garden. Photo: Creative Commons

Species come and go, sometimes as part of the evolutionary process of natural selection, other times due to natural catastrophes, or in the worst case, for anthropogenic factors. Unlike animals, plants don’t have any mechanism for surviving if their habitat is destroyed. Hence, they are more vulnerable to extinction; and even when they do survive, they can’t spread because new soil conditions favor other dominant species. Of the 30,000 plant species known to mankind, 12,914 of them have been evaluated, and is estimated that 68% of these are threatened species (Source: IUCN 2016).

The number makes sense when put in the context that more than 99 percent of all species that ever lived on Earth are now extinct. According to American biologist, researcher, and environmental theorist E.O. Wilson, by the year 2100 it is estimated that half of the current species inhabiting this planet, plant and animals, will be extinct. We are experiencing what scientist call “the sixth wave” of extinctions in the past half-billion years. The normal rate of extinction was about one to five species a year, but now it is 1,000 to 10,000 times this rate.

De-extinction is the process of bringing extinct plants and animals species back to life through cloning or selective breeding/seeding. Botanists and paleobotanists are now investigating this technique to resurrect ancient plants to our modern world. In 2012, National Geographic published an online article about Silene stenophylla, the oldest plant to be regenerated, which was grown from 32,000-year-old seeds. The efforts were led by a Russian team and they managed to germinate new seeds, using plant material trapped in the ice 124 feet below ground. The experiment suggests that the permafrost might be a depository for ancient plant and animal material.

With all of the controversy attached to de-extinction, this could be a corrective solution to our modern problem, but the mindset should change before going into this. It never hurts to remind that first mankind must take the preventive solutions to the possible extent, by avoiding activities that could end up destroying our biodiversity.

As landscape architects, we could look at what we have done with cycads– usually planted in interpretive and educational gardens – one of the oldest plants specimens to ever grow in our planet. And yet, their palmetto-looking form makes it fit for the aesthetical appeal in the profession. Can we picture now true prehistoric gardens in our communities? What about restoring entire plant communities? Only time will tell whether the era of the Anthropocene will be catastrophic or one of revitalization through technology…


South Gate, CA. Photo by Cristhian Barajas

South Gate, CA. Photo by Cristhian Barajas

Railroad bridges offer outstanding opportunities for the creation of viewpoints and for connecting pedestrian and non-motorized trails in the urban environment. The inherent layout of the majority of these structures favor the appreciation of natural and artificial scenery, such as canyons and water bodies. In locations where conventional pedestrian or vehicular crossings are far or non-extant, railroad bridges may become an informal connection for non-motorized mobility.

Most railroad bridges in the L.A. area experienced a transformation from wood to iron during the flood periods, which questioned the integrity of wooden structures and posed a larger threat to the population once the structures collapsed; thus, playing a major role during these type of disasters (Gumprecht 2001). Since then, uniform iron structures are standing across the urban riverscapes, some of them still remain. Such is the case of the Santa Fe Arroyo Seco Railroad Bridge, the oldest, tallest and longest extant railroad bridge in the City of LA, built by Santa Fe Railroad (Masters 2012), it became part of the Metro Gold Line in 2003 (Fisher 2010). These artificial landmarks were built and operated by the major companies of their time: Union Pacific Railroad, Southern Pacific, ATSF, BNSF, Amtrak and other modern commuter rail services.

According to a study conducted by the California Department of Transportation, there are over 7,635 miles of railroad lines in California. Along these, about 200 locations of railroad infrastructure in the state are considered obsolete. Some of these are old train stations, bridges, yards and even entire railroad branches.

Of the major railroad branches in the LA County, five are out-of-operation and six of them are in state of abandonment (Caltrans 2005). There are records of about 250 railroad bridges statewide, 31 of them are abandoned, closed to all traffic, derelict or in a state of disrepair. Out of all the railroad bridges in the state owned by railroad companies, only two of them are open to pedestrian traffic: the Juniata Cooke Greenbelt Trail/UP Overpass in Orange County; and the SC&MB – Aptos Creek Bridge in Santa Cruz County (Bridge Hunter 2016). It is imperative to expand and update the inventory of these bridges statewide.

The Government acknowledges the need to “identify abandoned rail corridors that have potential for use by non-motorized transportation and as links to improve access to public transit” (Caltrans 2005). As mentioned before, more and more often railroad crossings in a state of disrepair are being used as informal pedestrian crossings by the neighboring users, such as the case of the train track bridge in Santa Cruz, CA; which is part of an active railroad line connecting the Santa Cruz Beach Boardwalk and Murray St over the San Lorenzo River (video below).

The rails-to-trails conversion is the drosscape practice of reclaiming the right-of-way of train corridors which are abandoned or out-of-operation. Ongoing and recent projects of this type in the LA County are: the San Fernando Valley east-west bicycle path, the Whittier Greenway Trail, the San Fernando Road MetroLink bike path, the Long Beach Greenbelt Bike/Ped Path and the Exposition corridor. These projects range from 1.2 to 11 miles and have received funding from $1.1 to $6 million dollars.

For the case of active railroads, Caltrans (2005) suggests the incorporation of multi-use programs for in-operation rail corridors, which means they can accommodate for pedestrian and non-motorized transportation while also allowing for conventional railroad transit.

Some interesting pedestrian/biking bridges in the U.S. that used to be railroad bridges:

  • Junction Bridge Pedestrian Walkway, Arkansas.
  • Union Street Railroad Pedestrian & Bicycle Bridge, Oregon.
  • John Seigenthaler Pedestrian Bridge, Tennessee.
  • Big Four Bridge, Kentucky & Indiana.
  • Newport South Bank Bridge, Kentucky & Ohio.
  • Walkway Over Hudson Bridge, New York.
  • Depot Avenue Trail Pedestrian Bridge, Florida.
  • High Line, New York.


The John Seigenthaler Pedestrian Bridge. Creative Commons photo by Craig G.

The John Seigenthaler Pedestrian Bridge. Creative Commons photo by Craig G.

Opportunities for designers and planners increase when some of these potential pedestrian crossings share a similar design, layout, and structural behavior. According to the site Bridge Hunter, the through truss railroad design is featured 95 times across 250 recorded bridges in the state, giving a clear chance to develop prototypes for rails-to-trails scenarios or multi-use programs. At the moment, 52 of the 95 bridges are owned by railroad companies.

Offering good structural integrity, the adjacency to trail networks and proper safety measures could be kick-start qualifications to make a bridge candidate for these type of interventions. The character of the iron structures in most railroad bridges has already certain architectural appeal thanks to the contemporary marvels of civil engineering. Residents could immediately recognize these spaces as community landmarks.

For designers, however, the challenge arises when it comes to the development of secondary uses in these right-of-way sites. Ownership, liability issues, permits, and restrictions posed by design guidelines often conflict and end up driving out the idea of reclaiming the site for the nearby communities, unless there is a strong public interest in developing the zone.

For public agencies, the challenge might be more related to the proper maintenance and operation of the infrastructure. Railroad bridges offer a unique view of the cityscape. But if not surveilled properly, these spots usually have also the potential for becoming a hotspot associated with criminal activities, and as refuge for the homeless in the urban environment. This is translated into a negative perception of the site and unsafe transit conditions.

South Gate, CA. Photo by Cristhian Barajas

South Gate, CA. Photo by Cristhian Barajas

The panorama looks positive, with more often public and private agencies recognizing the importance of providing new pedestrian/biking connections to communities as encouragement for recreational activities and an aid in fighting poverty. Four components are key to make these projects happen: land owners, public agencies, designers, and community.

From the environmental justice perspective, some of the best views of the city from the urban environment are located in such inaccessible places like railroad and vehicular bridges, when in fact it should be the opposite. Non-motorized and green transportation should be rewarded with the best views of the city.