- Special Sections
- Public Notices
It would be interesting to see what “safety statistics” the Transportation Board reviewed and who the “representatives of the community” they reviewed were, as stated by D.D. Martin in the Los Alamos Monitor.
Reviewing is not research as implied; and I thought the community’s only true representatives were the councilors. The board’s initial 7-0 vote against roundabouts should have told them how the community at large would receive them.
Since I presented the Los Alamos safety data in my Monitor column back on Feb. 27, they obviously did not look at the Los Alamos safety data held by the county. I doubt very seriously whether they (“studied the engineering, reviewing simulations”) were presented or inquired about throughput versus volume flow either.
Undeterred by detractors, I have taken a look at how traffic flows through a roundabout with regard to traffic density. I used data from the National Cooperative Highway Research Program for the flow through a roundabout as a function of input demand and Los Alamos public records (Nu-Metrics traffic Analyzer Study done Aug. 12, 2010, sent to me by Leslie Bucklin from the county Feb. 8, 2011.
I assumed the roundabout flow to be optimal, “continuous flow” capacity to give the roundabout its best due. For a 130-foot roundabout, that is a vehicle every 4.8 sec.
In a string of roundabouts, it is doubtful that all will operate at optimal. If there is much heavy-duty truck traffic, traffic will surely slow down.
Combining the two sources of data produced the accompanying graph.
When traffic loads approach1750 veh/hr., there is almost no flow through any of the roundabouts shown. A 130-foot diameter roundabout is fairly large.
A 195-foot roundabout is about two-thirds the size of a football field and sidewalks will make it more than 200-feet in diameter.
To show the decreased traffic flow, I chose the middle sized one, which incidentally, covers 10 13-foot-wide lanes; the interstate minimum is 12-foot lanes.
Note that the only hour where Trinity Drive traffic flow was less than the roundabout continuous flow maximum was 6-7 a.m. One would be surprised to find that Trinity has less traffic load during the morning rush, 7-8:30 a.m. than it does during non-rush hours, 8:30 a.m.-4 p.m.
I wonder how the downtown merchants who complain that they are not getting enough business will react when the “flow-to-their-doors” is throttled.
Of course, the noon-time rush provides the biggest concentration of cars on Trinity. Are those merchants who depend on noon patronage ready for the number of vehicles that come into town to be halved (53 percent fewer cars through than now; down from 1,600 to 750 per hour?)
Some have voiced that their business on Trinity is walk-in; I doubt those businesses include the likes of Smiths, McDonalds, Sonic and a number of non-food businesses.
During the evening rush, when I presume labbies and even locals stop in town for something or other, the impact is significant, if not of noon level (45 percent fewer cars through than now; down 1,360 to 750 per hour.
If roundabouts could facilitate heavy flow-loads so well, federal engineers would have long ago applied them to interstates and other highways. They have not.
But, if the object is to limit the number of vehicles that can travel down Trinity to a 750 or fewer cars per hour pace, roundabouts will certainly do the trick.
Traffic, of course, will increase elsewhere for those not patient enough to endure the long, “funeral procession” lines of cars waiting their turn through numerous roundabouts, but still want or need to get into the town center.
If merchants are ready to tell citizens and visitors that they are satisfied with such throttling of the current “flow-to-their-doors” and are content to tell labbies to go home by way of the truck route, as some proponents of 2 lanes desire, then there really should not be much of a dilemma.
They should not gripe when business falls off, nor expect any increase in future years. We citizens who travel on Diamond Drive’s nice four-lanes will just go down the truck route during non-rush periods and forget about doing business where we are not encouraged to come.
Citizens who complain about additional flow on Canyon Road, a snail’s pace in the town’s center, and the joyless weaving around many roundabouts should never gripe again about how they are treated.
As far as those who do not live in Los Alamos, you will have been told what the county decision makers and planners think of you and your business. They get plenty of clams from the lab’s gross receipts to do as they please.
If you think I am too harsh on roundabouts, consider that the experts who have been chartered to do the designs are presenting a very rosy picture.
This is what experts are paid and directed to do. I am just an unpaid, skeptical citizen who has done some digging when what those expert have proposed seems so perfect as to be unbelievable even to the casual eye.
Joel M. Williams