State: Formula decides highway speed limits

July 31, 2013

The speed limits posted on roadways by the Texas Department of Transportation (TxDOT) are determined by the drivers themselves – at least those who drive safely.

Before posting a permanent speed limit sign, TxDOT conducts engineering studies to document the traffic flow. When an adequate traffic sample is recorded for the road being studied, the speed driven by 85 percent of the drivers under good weather and visibility conditions is considered the maximum safe speed for that location, according to TxDOT.

Val Lopez, a TxDOT public information officer based in Fort Worth, said that formula has been in use as a universal road engineering standard for decades.

“We determine what speed 85 percent of the motorists are traveling at,” Lopez said. “Then we post a speed we think is appropriate. Once we do that, we can adjust the speed.”

Some local drivers have complained about the 45-mph speed limit posted on the newly opened portion of Loop 567 that provides a link eastward from Weatherford Highway, then curving south into East Pearl Street. Other recently changed speed limits in Hood County have also been questioned.

If TxDOT receives enough complaints from local officials or from the public, speed zone limits sometimes can be changed. But, even then, testing of current traffic samples will determine whether changes will be made.

“We’d absolutely adjust it based on the study,” Lopez said.

Lopez said other factors used in determining speed limits include line of sight and intersections, but the “overriding” factor is the 85th percentile group. He said that those who travel too fast or too slow can present hazards for other drivers.

“Widely differing speeds – that creates unsafe travel situations,” Lopez said.

[email protected] | 817-573-7066, ext. 254

Loop 567 (new extension)

45 mph

Loop 567 (old)

65 mph

Glen Rose Highway

Southbound

Granbury city limit

55 mph

Just before Indian Mountain Ct.

60 mph

End of center divide

70 mph

Glen Rose Highway

Northbound

Just past Pear Orchard Rd.

60 mph

End of center divide

55 mph

Granbury city limit

45 mph

Weatherford Highway

Northbound

Granbury Cemetery

40 mph

All Seasons Self Storage

50 mph

Lake bridge

55 mph

Granbury city limit

60 mph

Weatherford Highway

Southbound

Granbury city limit

55 mph

Near Loop 567

50 mph

Daffan Mechanical

40 mph

Granbury Cemetery

30 mph

Highway 377 East

Eastbound

Just past Old Acton Highway

50 mph

Near Cleburne Propane

55 mph

Reese Plaza (Gateway Hills Ln.)

70 mph

Note: Eastbound speed goes to 75 mph about one-quarter mile east of Gateway Hills Lane.

Highway 377 West

Eastbound

Just before Loop 567

55 mph

Just past Paluxy overpass

50 mph

Highway 377 West

Westbound

Just west of Loop 567

70 mph

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Category: News Archived