Portland-based firm William Kaven Architecture has put forward a scheme to redevelop the soon-to-be demolished US postal building in the Oregon city, including a pair of towers built alongside a high-speed rail system.

William Kaven Architecture has proposed a complete overhaul of Portland's US Postal Office headquarters site in the Pearl District, which is planned to be razed.

The masterplan includes approximately​ ​five​ ​million​ ​square​ ​feet​ (464,515 square metres) of development for the city, with various mixed-use ​buildings​ and two linked skyscrapers – ​one​ ​of​ ​which​ ​would​ ​exceed​ ​970​ ​feet (296 metres).

If built, these towers would become Portland's tallest, and among the tallest on the west coast. San Francisco's Salesforce Tower, which topped out in April, currently holds the title at 1,070 feet (326 metres).

William Kaven Architecture hopes the complex will be considered as part of the city's bid for Amazon's second headquarters, which many urban areas across the US are hotly vying for.

​"What we​ ​have​ ​conceived​ ​is​ ​a​ ​dynamic,​ ​modern​ ​neighbourhood​ ​centralised​ ​around​ ​an​ ​extension​ ​of​ ​the​ ​park​ ​blocks," said Daniel Kaven, who founded the local firm with brother Trevor William Lewis in 2004.

"​The towers​ ​are​ ​large​ ​enough​ ​to​ ​serve​ ​as​ ​a​ ​headquarters​ ​for​ ​a​ ​Fortune​ ​100​ ​company,​ ​such​ ​as​ ​Amazon,​ ​and​ ​would​ ​anchor the​ ​entire​ ​district​ ​both​ ​architecturally​ ​and​ ​financially."

A glazed walkway, situated around ​680​ ​feet​ (207 metres) ​in​ ​the​ ​air would connect the two structures around halfway up, and house a ​botanical​ ​garden with expansive views of the city.

​"The​ ​buildings​ ​themselves​ ​would​ ​be​ ​high​ ​performance and​ ​energy​ ​efficient,​ ​with​ ​on-site​ ​power​ ​generation​ ​from​ ​photovoltaics​ ​integrated​ ​within​ ​the​ ​glazing," ​said Lewis.

This October, Kaven ​​penned​ ​an​ ​op-ed​ about the need to redevelop the postal site due to its prime location in the growing city.

In the DJC Oregon article, he critiques much of the city's developments, and calls for the creation of more public transit options and urban infrastructure.

The site is close to ​Union Station rail hub,​ ​Greyhound​ ​bus station​, ​and​ has good connections to ​Portland's​ ​local​ ​streetcar​ ​and​ ​bus system.​ ​

The design of the complex ​aims to integrate​ ​the new USPS building with ​a​​n upgraded ​transportation​ ​network, including a proposal for​ a high-speed​ ​rail​ system ​alongside​ ​other underground​ transit​ ​innovations.​

"This​ ​is​ ​our​ ​opportunity​ ​to​ ​lead​ ​the​ ​effort​ ​to​ ​build​ ​a bullet​ ​train​ ​network​ ​that​ ​links​ ​Portland​ ​to​ ​Los​ ​Angeles,​ ​San​ ​Francisco,​ ​Seattle​ ​and​ ​Vancouver​ ​from​ ​the​ ​heart​ ​of​ ​an already-existing​ ​downtown​​ ​​transportation​ ​hub," said Kaven.

The​ ​USPS Portland complex by William Kaven ​is​ ​currently​ ​in​ ​the​ ​conceptual​ ​design​ ​phase, and led by ​a subsidiary studio Kaven​ ​+​ ​Co.

The company intend​s ​to​ ​submit​ ​a​ ​formal proposal​ ​to​ ​the​ ​City​ ​of​ ​Portland's​ ​development​ ​arm ​Prosper​ ​Portland ​in​ ​early ​2018, after the firm began a​ ​formal​ request for quotation (​RFQ)​ ​process​ ​just last​ ​week.