Connecticut workers in the transportation and construction industries are advocating for increased infrastructure spending as they highlight a new report from the American Road & Transportation Builders Association.

The report, titled "The Economic Impact of Failing to Invest in Connecticut's Highways, Bridges and Transit," lays out two investment scenarios and their impacts over the next 20 years.

The first is if transportation infrastructure is funded to the levels laid out in Gov. Dannel Malloy's 2015 "Let's Go CT" plan. The second is for minimum investment, with federal funding and a 20 percent state match for bridge/highway investment, and transit investment at current levels. Average annual investment over the next 20 years for the two scenarios would be $2.42 billion and $1.28 billion, respectively.

The Connecticut Construction Industries Association commissioned ARTBA to complete the report after seeing the state House Democrats' budget proposal.

CCIA President Don Shubert said he was disturbed by two things in the proposal. The first was a shift in tax revenue from transportation to the general fund, and the second — also a facet of the state House Republicans' proposal — was a $700 million bond cap.

"We don't think diverting your attention from transportation is really going to help in the long run," Shubert said.

Similarly, Connecticut AAA spokeswoman Amy Parmenter said her agency has been "aggressively" campaigning for the transportation lockbox, to ensure that that funds earmarked for certain projects aren't used elsewhere.

"Can you imagine a situation where someone collects money from you under one pretense and goes and spends it differently?" Parmenter questioned. "I think in general that doesn't sit well with the voters, and it doesn't sit well with AAA."

As for the $700 million bond cap proposal, the state Department of Transportation estimates that a $900 million bonding level is necessary to support the transportation program, according to ARTBA's report.

DOT expressed concern that the lower bond cap could delay or cancel 22 highway, bridge and construction projects, including the $97 million Gold Star Bridge northbound span work between New London and Groton.

The report argues that greater funding for transportation infrastructure leads to more jobs across industries, increased business output that results in lower costs and fewer roadway fatalities, as well as savings to drivers due to less congestion and lower maintenance costs.

It estimates that the $2.42-billion-per-year, needs-based plan would save an average of $904 million per year in maintenance costs. The investment in construction activity would support 26,000 jobs annually, compared to 11,700 for the minimum investment scenario.

The report also estimates the impact of both scenarios on seven key industries in the state: health care/bioscience, insurance and financial services, advanced manufacturing, digital media, tourism and green technologies.

The estimates for advanced manufacturing jobs created under the two scenarios each year is 499 and 266, and for tourism, it's 2,658 compared to 1,432. Eastern Connecticut accounts for 27 percent of travel spending in Connecticut, according to the journal Tourism Economics.

The needs-based plan would allow for the replacement of 1,803 bridges over 20 years, the report estimates, while that figure is 831 for the minimum investment scenario.

The Federal Highway Administration reports 33.5 percent of bridges in Connecticut as "structurally deficient" or "functionally obsolete," compared to a national average of 23 percent.

As part of its 2017 list of America's Top States for Business, CNBC ranked Connecticut at 47 for infrastructure.

Neither scenario accounts for potential economic loss if the state were to shut down projects, and the minimum investment scenario does not account for possible cuts to operational costs or transit services.

"We could really easily fall below their minimum funding scenario in Connecticut, and that's a strong possibility the way things are going," Shubert said.

According to the report, the two scenarios were developed with guidance from the state DOT and Office of Policy and Management, using investment levels in DOT's 2017-22 capital plan.

Estimates for investment needs in the National Highway System and for bridges came from two different Federal Highway Administration models.

e.moser@theday.com