NAGOYA -- Central Japan Railway, which runs the country's busiest bullet train line, will roll out new cars to keep improving a service that has seen 50 straight months of passenger growth.

The Nagoya-based company, better known as JR Tokai, said on Thursday that it will spend about 104 billion yen ($866 million) on 20 N700A train sets and improvements to rolling stock already in service, including redesigned brakes. It plans to begin running all the trains on its mainstay Tokaido Shinkansen line, which links Tokyo, Nagoya and Osaka, at up to 285kph in the spring of 2020.

The investments "will enable us to raise our level of transportation safety and reliability," President Koei Tsuge told reporters in Tokyo.

With upgrades that include shortening braking distance by 5%, existing trains will be brought up to N700A performance, making that the uniform standard.

The Tokaido Shinkansen provides about 90% of the company's fare revenue. From August 2011 through this past September, monthly passenger volumes -- as measured along a portion of the track --- have logged an unbroken streak of year-on-year growth. Fiscal 2014 was expected to see dips from year-earlier levels that had been elevated by one-off events, such as the 30th anniversary of the opening of Tokyo Disneyland. Yet growth continued. So far in fiscal 2015, despite even higher bars to clear, ridership has continued to rise, helped by extra trains during peak hours. The faster speed has made this additional capacity possible.

On a roll

The 2020 target date "has absolutely nothing to do with the Olympics" to be held in Tokyo that year, said a person familiar with the company's plans. In fact, JR Tokai has been taking steps to improve passenger experience since the late 2000s.

The N700 series trains debuted in 2007, marking an improvement in acceleration on curves and comfort. JR Tokai also added such onboard amenities as in-seat power outlets and WiFi.

On March 14 of this year, Tsuge watched with pride as the first JR Tokai train to reach 285kph left Nagoya Station -- a milestone overshadowed by the opening of the new Hokuriku Shinkansen bullet line. The company had been waiting 23 years since the start of Nozomi, its fastest service between Tokyo and Osaka, to reach this speed.

With business travelers accounting for 60-70% of Tokaido Shinkansen passengers, nothing does more to improve service than shortening the travel time. At 285kph -- 15kph faster than the previous top speed -- the minimum travel time edges down to two hours and 22 minutes.

This buys just three minutes, which may not seem like much until one considers the difficulty of accelerating trains on a line that is roughly 40% curves. When the Tokaido Shinkansen opened in 1964, the trip took four hours. Getting to the current maximum speed involved some 43,000km of test runs.

Feat of levitation

A far greater undertaking is the creation of a magnetic levitation train line between Tokyo and Nagoya, which JR Tokai aims to open in 2027. It received approval to begin construction last October and is making steady progress so far.

The greatest challenge will be paying the projected 5.5 trillion yen construction costs. Going all the way to Osaka -- the eventual goal -- would cost a whopping 9 trillion yen. Since JR Tokai intends to finance the project entirely on its own, it will need to milk its cash-cow bullet train for all it is worth.

Budget airlines may yet undermine its advantage as a Tokyo-Osaka connection by cutting fares. JR Tokai is reluctant to resort to discounts, so it will try to stay competitive by improving service instead.