A transitway linking upper Montgomery County’s fast-growing biotechnology corridor with the Metrorail system could be built four years earlier and for $310 million less than a state plan would allow, according to a privately funded analysis released Tuesday.

The analysis, by the Baltimore engineering firm Kittelson and Associates, found that the first nine-mile segment of the so-called Corridor Cities Transitway could be built between the Shady Grove Metrorail station and the Metropolitan Grove MARC station with significantly lower right-of-way costs, fewer costly bridges and some scaled-back stations. The study was paid for by a dozen businesses, developers and institutions in the Gaithersburg area, including Johns Hopkins University and Shady Grove Adventist Hospital.

State plans call for construction of the first section to begin in 2018 and the line to open in 2020 at a cost of $545 million. The business group’s engineering firm said construction on its plan could start in 2014, with the first segment opening in 2016, at a cost of $235 million.

William Robertson, president of Adventist HealthCare, said it’s a “viable” option for the Maryland Transit Administration (MTA) to consider. A transitway must be built as soon as possible to help Montgomery compete against Fairfax County and other parts of the Washington region for jobs and economic growth, he said.

“Timing is everything,” Robertson said. If a transitway isn’t built until 2020, “half the growth opportunity has already gone by.”

MTA spokesman Terry Owens said state planners will evaluate the analysis to determine if a transitway could be designed and built more quickly while still being able to accommodate longer-term ridership demands.

The business group released the analysis as part of a county task force’s report recommending construction of a 160-mile network of express bus lanes throughout Montgomery at a cost of $1.8 billion. A complete 15-mile Corridor Cities Transitway between Shady Grove and the Clarksburg area would be part of that network but would move along a different funding path.

The private analysis, which Robertson said cost about $77,000, could prove significant because lower construction costs would help a transitway qualify for less competitive federal construction money targeted at smaller projects. A transitway is already behind two other Maryland transit proposals: a light-rail Purple Line between Montgomery and Prince George’s counties and a light-rail Red Line in Baltimore.

A Corridor Cities Transitway is likely to be one of the first links in any countywide busway network because much of the development planned for the Gaithersburg area west of Interstate 270 would stall without it.

“If we fail [to build more transit], it will be a catastrophic failure of a magnitude this county cannot afford,” Montgomery County Executive Isiah Leggett (D) told public officials and business leaders gathered for the task force’s unveiling of its report on Tuesday.

The business group’s engineering firm said the state could save significant right-of-way costs by running buses down medians or in traffic lanes on less-traveled roads, such as parts of Great Seneca Highway. The state also could save on costly bridges at busy intersections by timing signals to favor buses with longer green lights and building lanes to help buses get around stopped traffic. The proposed changes would add four miles each way to buses’ travel times, the engineering firm said.