In this week’s Q&A we answer that question and two others, about Interstate 5 ramp meters and how city officials hold contractors accountable for tearing up roads.

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Since Amazon and other tech giants are reshaping Seattle’s South Lake Union neighborhood, do they pay for ways to alleviate traffic congestion?

One Sammamish resident, who works downtown, wants to know.

In this week’s Traffic Lab Q&A, we answered that reader’s question and two others about Interstate 5 ramp meters and how city officials hold contractors accountable for tearing up roads.

Traffic Lab is a Seattle Times project that digs into the region’s thorny transportation issues, spotlights promising approaches to easing gridlock, and helps readers find the best ways to get around. It is funded with the help of community sponsors Alaska Airlines, CenturyLink, Kemper Development Co., NHL Seattle, PEMCO Mutual Insurance Company and Seattle Children’s hospital. Seattle Times editors and reporters operate independently of our funders and maintain editorial control over Traffic Lab content.

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Q: Google, Facebook, Amazon and other tech giants are building and leasing more and more space in South Lake Union, adding to the massive congestion already in that area and the surrounding freeways. Why isn’t the city asking those companies to pay for traffic projects to ease congestion?

— Demitri Anastassopoulos, Sammamish

A: In some ways, the city already does. When developers submit permit applications for construction, officials review how their projects will impact transit, drivers, pedestrians and bicyclists in the surrounding area.

Then, officials require those applicants to directly pay for infrastructure projects or make payments through the Seattle Department of Transportation (SDOT) for future improvements. Such mitigation payments are aimed at reducing the development’s effect on transportation.

In 2012, the Department of Construction and Inspections, along with SDOT, developed a program to make that payment process more efficient, specifically in South Lake Union and Northgate. Officials targeted those areas in anticipation of a lot of growth.

Private developers in those areas can pay SDOT directly for pre-identified transportation improvements, which include traffic projects as well as updates to bicycle and pedestrian routes.

To calculate the mitigation payments, officials consider the type of development project and the number of people it would have coming and going in the area.

Whether those payments are enough to cover what’s needed to ease congestion associated with new development is a bigger question. Some of the roadway issues are a result of existing problems, which the mitigation payments wouldn’t address.

Q: Does anyone monitor ramp meters on the entrance ramps of I-5, or are they now programmed automatically without regard to real traffic conditions? I’ve gotten on the freeway when traffic was moving relatively quickly — without any line at the light — though still I’ve had to wait.

— Marilyn Smith, Seattle

A: It’s 2017 — of course humans don’t manage the meters.

But the computer system does takes into account real-time traffic speeds and congestion by using detection devices that include magnetic loops and radar signals, according to the Washington State Department of Transportation (WSDOT).

The state’s busiest highways have the meters, which signal to drivers with a green light when vehicles can enter a freeway.

WSDOT says the delays between signals range between four and 15 seconds.

The detection devices feed data to the ramp meters to alter their cycles based on current conditions, WSDOT spokeswoman Nicole Daniels said.

“The meters go off of the traffic flow,” she said. For instance, they lengthen the time between signals after crashes or when traffic is backed up.

The meters deactivate when the detection monitors show freeway traffic running smoothly, and workers sometimes manually switch the meters off when there’s an incident, Daniels said.

Transportation crews (yes, humans) do, however, keep an eye on the computer system at the department’s Traffic Management Centers, which are what WSDOT calls the “nerve center” of statewide highway monitoring across Washington.

Q: What are Seattle officials doing to keep up with repairs to our roads and hold accountable independent contractors who tear up the roads for building construction services?

— Gavin Gee, Seattle

A: Coincidentally, SDOT just made changes to its policies for addressing this very issue.

At the start of this year, the department implemented updates to its existing requirements for anyone affecting right-of-way spaces, which includes contractors and developers digging into streets or sidewalks.

The revisions included shortening the time frame contractors have to make permanent fixes to roads they tear up, as well as lengthening the time they are prohibited from ripping into newly paved streets.

The city also tightened exemptions and hired three dozen new inspectors to monitor compliance with the city’s regulations. A city inspector and agents may “be on the job site at any time,” according to the rules.

While making the policy updates, officials said they kept in mind the $930 million Move Seattle levy that voters approved in 2015, which calls for numerous transportation projects across the city, including repaving streets and making areas around schools safer for pedestrians and bicyclists.

Besides that, SDOT recently created what’s called a Project Coordination Office, which aims to mitigate construction-related issues by collecting data on projects and organizing meetings with people involved.

The office “brings anyone working on high-volume streets together to improve project sequencing and reduce the time when the street is under construction,” the department said.

City officials routinely publish information on street projects for the upcoming year, showing their locations and potential timing.

You can find those maps and details on SDOT’s website.