Ada County Highway District

ACHD's Road Wizard Sunday, August 19, 2018 ACHD's Road Wizard

Thumbs up for chip sealing, but it isn't being used on Emerald and 11th streets; creating a through/left-turn option lane on Idaho Street onto 9th Street could double the trouble; radar vehicle speed display signs will not double as speeding ticket technology

The Road Wizard Replies

Dear Road Wizard: I have read your cost/benefit analysis of chip sealing many times in this column and I'm sold. It is clearly the most durable and cost effective road surface. I'm glad to see it being applied on Overland Road. But I'm curious as to why asphalt is being applied to streets like Emerald and 11th streets rather than a chip seal?


Road Wizard:

Thank you! I have been chipping away at the negative perceptions regarding this road treatment for years. But of course chip sealing has its drawbacks, and it isn't the best solution for all road surface needs.

On Emerald Street/Americana Boulevard, work is underway to install continuous bike lanes and sidewalks. The road itself needed new pavement to match the level of the new sidewalks, and chip sealing is not used for that purpose.

In Downtown Boise, 11th Street was just too far gone for a chip seal. The pavement was deteriorated and chip sealing would be like brushing fresh paint on top of old, peeling paint, so the pavement was ground down and new asphalt was applied.

Chip sealing is used on roads that are in relatively good condition. It provides a fresh wearing surface, seals the roadway, and can prolong the life of a road up to 12 years, all at a relatively low cost. But eventually, fresh, more costly asphalt will have to be used instead.

Dear Road Wizard: Love the column. Quick question: Driving west on Idaho Street, drivers turning left onto 9th Street are forced into the left-most lane. With so many motorists trying to turn onto 9th, I see traffic regularly back up all the way to 5th Street during the evening commute. Why not give center lane drivers on Idaho the option to turn left onto 9th? Seems it would significantly reduce congestion in the already busy downtown corridor.

North End Kev

Road Wizard:

That long line of traffic can certainly give the impression that left-turning drivers should get more attention. But the delay has more to do with those drivers having to yield to pedestrians.

There aren't as many left-turning vehicles as it may seem. Current evening peak hour counts show 300 vehicles turning from Idaho onto southbound 9th. That is compared to 1,050 through-traffic drivers in the same hour.

To make the left-turn lane change, the leftmost lane would have to be left-turn only and the next lane over would then double as a through/left-turn lane. After performing a computer simulation, it was clear that altering the lane configuration in this manner would, on average, nearly double the overall intersection delay for drivers. Consequently, it's not a recommended change at that location.

Dear Road Wizard: Could the radar vehicle speed display signs installed on various roadways throughout Ada County eventually be upgraded so that speeding motorists would be issued citations?


Road Wizard:

As in speed camera technology? Anything like that would likely need state lawmaker approval. Additionally, automated speed-detecting, ticket-issuing systems have been pretty controversial and are expensive to operate.

But according to the Center for Disease Control, speed cameras have resulted in the reduction of speeding vehicles between 14 percent and 65 percent. Speed cameras were also found to reduce the total number of crashes.

Standard police speed enforcement techniques can also be effective. In 2017, Boise Police issued nearly seven thousand speeding tickets.

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