BOSTON (SHNS) – Imposing a percentage-based fee on every ride-hailing trip, studying an extension of the Green Line’s E Branch into Hyde Square, and scrapping parts of a business-opposed local tax option are among the changes senators proposed to a major transportation investment bill set for debate Thursday.

Lawmakers filed 275 amendments to the Senate’s $16.9 billion version of a multi-year transportation bond bill (S 2813), the vast majority of which seek earmarks for specific transit or roadway projects in their individual districts.

Several of the proposed changes tackle larger-scale policy shifts included in or omitted from the bill.

Amendment 138 from Lynn Democrat Sen. Brendan Crighton would alter the fees charged to rides on services such as Uber and Lyft from the current flat per-ride amount to a scaled structure, calculated at 4.25 percent of the fare for a shared ride and 6.25 percent for a non-shared ride.

If approved, the amendment would put the Senate on record this session as supporting a change to the $0.20-per-ride flat fee for ride-hailing trips.

The Transportation for Massachusetts advocacy coalition listed Crighton’s proposal as one of its six “priority support” amendments ahead of Thursday’s debate.

Somerville Mayor Joe Curtatone, who joined the group and other activists at a Wednesday event, told the News Service that the Senate “absolutely” should embrace increased fees on ride-hailing services.

“That’s one of the many creative ways of bringing in more revenue to fund, to elevate service, to expand service, to make investments in transit expansion,” Curtatone said. “Given the fact that communities like Somerville and others are where you generate a lot of these different rideshare services, it makes all the sense in the world.”

Both Gov. Charlie Baker and the House have each supported updating that structure, but their versions would keep it flat. Baker proposed an increase to $1 per ride as part of his fiscal year 2021 budget. The House’s massive transportation tax bill would have kept the fees at $0.20 for shared rides, increased them to $1.20 for single-passenger rides and bumped them up to $2.20 for luxury rides.

“We can negotiate and bargain on exactly which of these approaches is best, but what I can think everyone can agree on is keeping it at $0.20, which is far below our peers and not reflective of the impact that these rides are having, is the worst option,” Transportation for Massachusetts Director Chris Dempsey told the News Service.

Other amendments the group backed include amendment 249, filed by Worcester Democrat Sen. Harriette Chandler, that would index the contract assistance the state pays to its 15 regional transit authorities to increase alongside annual inflation.

Two others would implement short-term pilot programs altering how Massachusetts charges roadway users.

Amendment 132 filed by Boston Democrat Sen. Nick Collins would require the Department of Transportation to launch a pilot program by Feb. 1, 2021 testing the impacts on traffic and revenue if tolls vary based on time of day, a system known as congestion pricing. Winchester Democrat Sen. Jason Lewis proposed amendment 80, which would create a task force and order a pilot studying the feasibility of imposing a mileage-based fee on all vehicle owners.

The House previously approved creating a commission to study congestion pricing, similar to the baseline Senate bond bill, but Dempsey said it is crucial to go a step further and ensure the state tests the practice.

“We think it’s important that commission be paired with real-world piloting and testing so the commission is not just an academic exercise,” he said, adding that Greater Boston is the only one among the country’s 10 most populous regions with no time-of-day variations in roadway tolls.

One of the most significant proposals in the underlying bill would authorize regional ballot initiatives for transportation purposes, a system in which any city or town could approve a surtax within its borders and direct the additional revenue toward transportation revenue.

Before the increase could take effect, a municipality’s governing body would first need to authorize a surtax on the sales, real or personal property, room occupancy or vehicle excise tax and then secure approval from a majority of voters through a ballot question.

Two or more communities could join together to approve regional surtaxes as a way of funding transportation projects that impact multiple areas.

Amendment 239 filed by Sen. Diana DiZoglio, a Methuen Democrat, would make the sales tax ineligible for a potential surtax, while amendment 230 sought by DiZoglio and Minority Leader Bruce Tarr would scrap the regional ballot initiative proposal altogether.

The Retailers Association of Massachusetts, one of the state’s largest business groups, circulated a letter to senators on Wednesday asking them to support the amendments, arguing the surtaxes could damage small businesses already struggling under the weight of the COVID pandemic.

“The sales tax option ignores the fact our consumers are virtually all within an hour’s drive to New Hampshire, and the fact that many international Internet sellers — like Alibaba — and even national sellers below tax collection thresholds, do not collect the state’s sales tax,” RAM President Jon Hurst wrote. “And during COVID-19, the facts are our consumers have gotten all too willing to send their billions of discretionary spending dollars out of state by purchasing on their smart phones.”

“Higher taxes for shopping local are bad public policy which will send spending out of state and will undermine the already tenuous future of our Main Streets,” Hurst continued.

He argued that transportation funding is more appropriately addressed at the state level “through user fees and taxes which have a direct connection to transportation.”

The Senate does not intend to tackle any such statewide transportation revenues this session, despite the House approving more than $500 million in tax and fee hikes for that purpose in March.

Rep. William Straus, the House’s Transportation Committee co-chair, said in an interview that he also worries about the viability of regional ballot initiatives, indicating that even if the measure is approved by the full Senate, it may not survive the conference committee negotiation process.

“My concern about regional ballot initiatives has always been that it’s essentially grafting onto transportation policy a type of Proposition 2 1/2 system where whether you get good roads, safe roads, or a good transportation system depends on the variables of local municipal elections,” Straus said.

He pointed to similar systems in other states as unreliable, arguing that projects funded through ballot initiatives had funding revoked by later ballots.

Straus said regional ballot initiatives could also deepen regional inequities because lower-income communities have less of a tax base on which to build transportation funding.

“I don’t think it’s fair to ask those communities to meet the same standards that some of the wealthier either counties or municipalities face,” he said. “If anything, I think this kind of system could separate us more than bring us together.”

Depending on which amendments the Senate adopts, the original multi-year borrowing authorization of $16.9 billion is likely to swell. Both branches often tackle a large portion of bond bill amendments by bundling them together to be considered in a single vote.

In March, the House Ways and Means Committee proposed a $14.5 billion version of the transportation bond bill, but the bottom line grew to $18 billion through amendments.

House leaders have expressed skepticism, however, that they can support all of that borrowing without the additional revenues they backed that will not emerge in the Senate this session.