Express lanes | Concrete

Q: Why does it so often seem Interstate 5's reversible express lanes are open in the wrong direction on weekends, particularly on game days when so much traffic is headed in the other direction?

North Seattle resident Drew Lienau is a weekday commuter to Bellevue. So it makes sense to him that the express lanes are open southbound in the morning and northbound in the evening. But the pattern is about the same on weekends, even though, in Lienau's opinion, the needs are very different.

"There are often freeway backups going south into Seattle throughout the day and evening, and rarely any going north," he said. "Would it not make more sense to have the express lanes only go south on weekend afternoons and evenings?"

A: The state Department of Transportation (DOT) determines the direction of express lanes on I-5 and Interstate 90 to benefit the greatest number of drivers, said department spokeswoman Myly Posse. And that's determined by annual studies of traffic volumes.

Weekdays, I-5's express lanes are southbound from 5-11 a.m., and northbound from noon to 11 p.m. On Saturdays and Sundays, it's southbound from 7 a.m. to noon, and northbound from 1-11 p.m. But the state does delay switching directions at times because of major events, such as games at Safeco Field, Qwest Field and even Husky Stadium, Posse said.

On Sunday a week ago, I-5's express lanes were southbound an extra two hours, and I-90's express lanes were opened to westbound traffic to accommodate Mariners game traffic. Normally, I-90's express lanes are westbound from 1 a.m. to 12:30 p.m., then eastbound from 2 p.m. until midnight weekdays, and eastbound only from 2 p.m. Fridays until midnight Sundays.

Vinh Dang, a DOT freeway-operations engineer, says it may appear that traffic in the opposite direction is more congested, but that's because express lanes are doing a good job of managing congestion.

Traffic patterns change over time, however. "If we see a need to fundamentally change the direction of the express lanes, we will," he said.

But based on the state's studies, Dang says it would not make more sense to have I-5's express lanes open southbound on weekend afternoons and evenings.

Q: David Wright of Seattle recalls hearing some time ago that scientists had developed a new concrete formula that doesn't absorb moisture, thereby extending its useful life considerably. Maybe the Romans used a similar mixture, he says. Maybe that's why some of their buildings still stand.

"Replacing the [Alaskan Way] Viaduct and the [Highway] 520 bridge, among other big projects, are huge investments funded by the taxpayer, and it would be good to know we are getting the most for our money," he said. "Is the [state Department of Transportation] requiring this new concrete formula so that replacing bridges and roads isn't necessary every few decades?"

A: Jugesh Kapur, a bridge engineer with the DOT, says the department is on the cutting edge in the use of construction materials, including concrete. "We use high-performance concrete for major bridge components that includes materials to make it easier to cast, makes it stronger and able to withstand corrosive materials such as road salts and oils."

Kapur says the state uses epoxy-coated rebar in most bridge components. The rebar has a protective coating that stops corrosion and extends the life of concrete.

Epoxy-coated rebar has been used by the state for nearly two decades. And if the Alaskan Way Viaduct were replaced or a new Highway 520 bridge built, the same high-performance concrete and epoxy-coated rebar would be used, he said.

"We now design bridges for a service life of 75 years, compared to the 50 years they were designed for a few decades ago."

Bumper note

Most area youngsters not already back in school are going back this week. And with the new school year, there's a new emphasis on traffic speed in school zones.

The speed limit in school zones is 20 mph. And to call attention to that, a number of jurisdictions in King and Snohomish counties have started installing flashing yellow beacon lights atop speed-limit signs in school zones to warn drivers to slow down.

In unincorporated Snohomish County, all 40 public elementary schools will get the flashing beacons. Statewide, the flashing lights and signs will be installed at the entrances to nearly 160 school zones.

In King County, the new lights will be installed near 18 elementary schools and one middle school. But Seattle is not yet a part of the program.

A Washington Traffic Safety Commission study indicates the flashing beacons are effective in slowing traffic. A speeding ticket in a school zone is $177.