| A peer review requested in early August by the Transportation Board was
provided on August 30, 2011 by Ourston
Roundabout Engineering. Ourston's
review confirmed our important conclusion that the proposed single-lane
roundabouts would not have enough capacity to handle existing peak traffic
on NM502. |
"Our analysis shows that single lane roundabouts
will not adequately handle the
existing or future traffic volumes for select approaches." |
|
| Ourston agreed with some of our other criticisms
of MIG's Study. |
"Adding right hand turn lanes in the future
condition is not a realistic way to add capacity." |
|
"When V/C ratios exceed 0.85, queuing
and delay estimations are highly variable and unpredictable.
It is not recommended to design for V/C ratios exceeding 0.85." |
|
| Ourston also suggested that two-lane roundabouts
could be appropriate for use on NM502. For several reasons, I consider that
this would be unwise and would not meet Los Alamos County goals: two-lane
roundabouts are yield-intensive and require quite a bit of real-time decision
making (conditions difficult for non-aggressive drivers), two-lane roundabouts
have many built-in traffic conflicts, and
two-lane roundabouts present complications and hazards to pedestrians, bicyclists,
and motorcyclists. |
