Q Good news from Utah, which last week began raising the speed limit to 80 mph on many of its highways. Perhaps Caltrans and CHP will finally figure it out here in the people's republic and follow the 85th percentile rule allowing sane speed limits. ...

Ron Linden, Sue Allen and several more

A Like on Interstate 5? Here's a great example of laws keeping pace with reality. Interesting that crashes are down!

Q It seems that some freeways in the Bay Area and the state, especially Interstate 5, have archaic speed limits. When was the last time speed limits on our freeways were determined? With the way cars are designed today, is it conceivable they could go 80 mph on I-5? Most people already go that fast, if not faster, if the CHP isn't watching.

Jonathan Roisman

Pleasant Hill

A Caltrans says it has no plans to raise the speed limit on I-5 from 70 to 80 mph. Utah increased the speed limit on 289 miles of what it considers rural highways and interstates (see map below) after studying the idea for several years and testing it on a few roads.

The speed limit in California was last raised in 1995 from 55 to 65 mph on most highways. A state survey of nearly two dozen highways a few years later found that the change had little impact on how fast we were traveling. On those highways where the limit jumped to 65 mph, average speeds increased from 68.3 to 68.7 mph, an increase of less than half a mile per hour. Where the limit went to 70 mph, speeds rose from 71.6 to 72.1 mph — also an increase of half a mile per hour.

The Utah Department of Transportation found that vehicle crashes decreased slightly in existing 80 mph zones. They attributed the increased safety to more vehicles traveling at the same speed.

Q Sad to hear there's no plan in the foreseeable future for a third lane line on I-5. But since the largest problem with slowing traffic on that drive is the trucks, what about a cheaper change? The difference in the speed limits between autos and trucks is 15 mph (70 vs. 55 mph) for the entire stretch from Westley to Highway 99.

If trucks weren't limited to being so much slower than car traffic, it seems there would be a lot less of the "slow traffic in the left lane" problem. It's not like there's a lot of merging traffic or any sort of cities.

Michael Bartlett

Los Banos

A Again, there is no move afoot to allow truckers to go faster on I-5. State officials say that at 55 mph, it takes a big rig 81 feet per second to stop, but at 70 mph it's 103 feet per second.

Q Bonjour again, Monsieur Roadshow! I had to drive over Highway 17 last Friday. On my way over, I noticed fresh tagging on the sound wall before the Camden exit. Grrrr. However, imagine my glee at seeing a workman with a paint sprayer painting over the tagging about an hour later on my return trip to Santa Cruz. Now THIS constituted a GREAT day! Thumbs up to the workman who performed this task! Bravo!

Karen Poret

Santa Cruz

A Bravo indeed.

Look for Gary at Facebook.com/mr.roadshow or contact him at mrroadshow@mercurynews.com or 408-920-5335. Also follow Mr. Roadshow at Twitter.com/mrroadshow.