Frequently Asked Questions


Please see our roundabouts page for detailed discussion of roundabouts!

Didn't the community already reject roundabouts in 2006?

On the contrary! In 2006, one design alternative for Diamond included three multi-lane roundabouts in quick succession. The roundabout design was favored by the Fire department, the Police department, the County Transportation Board (6-1 in favor), and LA Walks, along with many citizens. After the Council had voted to build the roadway with roundabouts, a 10-signature petition and vociferous last-ditch campaign by those opposed managed to convince council to reverse their earlier decision and install signalized intersections. There just weren't enough voices in favor of them after the Council had already voted for them. This is why we need people to keep voicing their support for a better Trinity!

What's wrong with traffic lights?

Traffic lights are a well-established traffic control device, but in order to build them, an intersection must meet one of a handful of warrants established in the Manual of Uniform Traffic Control Devices (MUTCD). At current and predicted volumes, no additional intersections on Trinity meet these warrants.

The "A2" option preserves the three existing traffic lights on Trinity, adding up to 5 roundabouts.

Don't roundabouts slow down traffic?

Traffic through roundabouts moves at a lower but continuous speed, which results in quicker commute times. Because traffic is not interrupted by red lights, the average end-to-end time for traveling Trinity would actually go down with roundabouts. Does that sound counter-intuitive? Think about it the next time you and 15 other drivers are stopped so a single car can turn left: roundabouts never have red lights.

Aren't roundabouts more dangerous?

The Insurance Institute for Highway Safety, in a 2000 publication, illustrates a study showing roundabouts to have 40% fewer vehicle collisions, 80% fewer injuries, and 90% fewer serious injuries than the signalized intersections they replaced. Because speeds are reduced through the intersection, pedestrian safety also improves. Bicyclists fare about the same with modern design guidelines.

Aren't roundabouts more dangerous for bicyclists, though?

Not if they're designed to current standards. Early roundabout designs experimented with bike lanes in the roundabout: this resulted in more collisions than signalized intersections, and the idea was scrapped. Modern roundabout design allows bicyclists room to get on the sidewalk and navigate as a pedestrian, while experienced cyclists can ride through the roundabout with the rest of traffic.

Shameless plug: if you're interested in becoming an "experienced cyclist", email Neale: I'm a League of American Bicyclists Certified Instructor and teach regular traffic skills classes.

Won't roundabouts make emergency response more difficult?

Not according to the Federal Highway Administration. They say emergency responders are better off at roundabouts, since there's no chance of someone T-boning them as they proceed through a red light. Not only that, the reduced rate of crashes at roundabouts means they don't have to respond to as many calls.

Wouldn't roundabouts slow down evacuation?

They would help, by allowing free flow of evacuating traffic. Roundabouts never have red lights, and don't need electricity for normal operation. Una Smith's 2010 letter to the editor tells the story of how one Georgia town installed roundabouts after suffering signal-induced gridlock when evacuating for Hurricane Floyd.

Aren't roundabouts harder to plow?

Yes, actually. We consulted county staff about this and the response was that roundabouts are indeed more challenging to plow. The A option reduces the amount of road surface to plow, though, and gives plows a landscaped area for plowed snow to pile up. Overall it might not be any more time-consuming.

I grew up in a town with traffic circles and they were horrible. What makes these any different?

What you probably experienced was a traffic circle, or rotary, which did indeed perform poorly. Roundabouts are a newer design with demonstrated benefits not only over rotaries but also signalized intersection. Wikipedia has a good article about the difference between roundabouts and rotaries

Roadway design

Isn't it going to slow people down to only have one through lane?

NM502 already has a single through lane in each direction, as anyone who has ever driven in or out of town on the main hill road knows. The "A option" has a through lane in each direction with dedicated turn bays, much like NM502 past the gate. This would provide continuous flow for through traffic, with pullouts for turning traffic to not impede anyone behind them. This results in better end-to-end performance than the current design, in which turning traffic can stack up dozens of cars for hundreds of feet as they all try to make a lane change (think of the turn into the hospital).

Won't slow drivers impede traffic?

Yes, slow drivers slow down traffic on any roadway, be it an interstate highway or a downtown road. There are three main points to bear in mind here:

  1. It's not a race: we want people to enjoy the beauty of our downtown, not zoom through as fast as they can.

  2. A traffic count by MIG revealed that most off-peak trips on Trinity are to a downtown destination anyway; most people aren't using it as a through road.

  3. We shouldn't design a roadway to optimize for infrequent losses of just a few seconds. According to Google Maps, it is 1.8 miles from Diamond to Canyon along Trinity. That's 185 seconds (3 minutes) at 35 miles per hour, and 259 seconds (4½ minutes) at 25 miles per hour. We don't need to base a roadway design out of fear of an 74-second delay once out of every 60 or so trips.

Is this going to hurt local business?

Most local businesses prefer slower-moving traffic: drivers can look in the windows at merchandise, have time to consider making a purchase, and walking from business to business is easier. People don't shop while they're in their cars!

Will option A impede emergency vehicles by giving drivers nowhere to pull over?

Drivers can pull right into the bike lane to let emergency vehicles through.

Couldn't we build tunnels or bridges for pedestrians?

Any new tunnel or bridge would need to meet ADA requirements, which, among other things, means it would need to accomodate a wheelchair user. This means either long ramps, or electric outdoor elevators, and either of these options would not fit in the current amount of right-of-way the county owns.

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