Q On your next Dirty Dozen list, I think the worst traffic hot spot has to be the Highway 237-Interstate 880 interchange. If you combine squeezing traffic from 680-237, 880, and the McCarthy Ranch ramp into two lanes, cars blatantly crossing double white lanes (why aren't there dividers?), and traffic jams well past commute hours, there's the recipe for a pretty miserable drive.

Raymond Centeno

A And ...

Q When heading west on Calaveras Boulevard, there are two lanes that merge onto 237, but there are also two lanes that do nothing but go up to McCarthy Boulevard. Why was it designed this way? Will there be some future use for those lanes that I'm not understanding?

Keith Love

Milpitas

A No. The McCarthy overcrossing was designed before county voters passed a half-cent sales tax to remove the traffic signals on Highway 237 and widen it to a six-lane freeway. When that tax was approved, Milpitas did not want all westbound freeway traffic to have to go across McCarthy, so officials asked for a design change to allow for a two-lane left lane "slip-ramp," which is what is there now. The two right lanes currently going up to McCarthy provide access to north and south McCarthy. There are no plans to add any lanes for freeway access.

Q Am I the only chump who obeys the law and doesn't cross over the double white carpool lane line on 237? I ride a Honda sport bike and have seen other motorcycles, cars, trucks, a bus, and an ambulance not on a call cross over the double white line.

Norm Ngim

Milpitas

A You are not a chump, but this problem persists. Future FasTrak lanes on other roads may not include the double white striping.

Q Every time I read that "driver cannot cross the double white line" or words to that effect in your column, I either cringe or laugh out loud (depending on my mood). What? Did Mr. Spock install a Vulcan force field along the double white line to prevent drivers from crossing? If he did, it ain't working so good, because I see drivers cross the double white line on 237 all the time.

How about another Roadshow wager? When will the state convert all current freeways to toll roads? It is going on now, one lane at a time.

Art Tarsa

Redwood City

A It will never happen. Carpool lanes will be converted to toll lanes, but not entire existing freeways.

Q You mentioned that a new FasTrak transponder is coming that can be turned on and off. I have been hesitant to get a transponder because I drive a plug-in hybrid and didn't want to risk either being incorrectly charged or having to keep taking the transponder off the window such that it eventually wouldn't attach properly. What you wrote about the new transponder made me more interested. Do you know when it might be arriving?

Nelson Lu

A Transponders with an on-off switch are now available in L.A. and should be coming to the Bay Area late next year.

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