Day 2: Gilberts Corner and Traffic Calming

Gilberts Corner is the intersection of Route 15 and Route 50.  For many years this was a signalized intersection until it was redesigned with three roundabouts in 2008.  

One of the common refrains from the special interest groups is: The roundabouts at Gilberts Corner worked so let’s build them on Route 15 instead of widening. Below is a satellite picture of the Gilberts Corner intersection.

First some volume numbers for the Gilberts Corner intersection:

Route 15 – 14,000 Annual Average Weekday Traffic (AAWDT)

Route 50 – 18,000 Annual Average Weekday Traffic (AAWDT)


Satellite picture of Gilbert's Corner

Both Route 50 and Route 15 at Gilberts Corner are at or within the 18,000 vehicle per day capacity constraint for a 2 lane road. There are three key reasons why the three roundabouts work (for now) at Gilberts Corner:

1.      Balanced Directional Volume – The intersection has near equal volume coming from all directions (unlike Route 15 North). Having balanced directional volume is a key part of Mr. Spack’s research on successful roundabouts that was cited yesterday.

2.      Three Roundabout Design – The three roundabout design allows vehicles to be dispersed and follow the path of least resistance.  For example, the roundabout at Howsers Branch Drive allows some Westbound Route 50 volume to avoid the main roundabout and head south on Route 15. See the red arrow above. This three roundabout design is neither an option on Route 15 North nor has it been proposed by the County. It is simply a non-starter.

3.      Usage of 4 Lanes of Travel – The AAWDT traffic count of 32,000 for the combined intersection is NOT handled by a 2 lane road with a roundabout as the special interests would have you believe. There are 2 lanes on Route 15 as well as 2 lanes on Route 50. If we include the Howsers Branch cutoff, there are 6 lanes in play at this intersection.

The three roundabout situation at Gilberts Corner, while effective for now, is in no way a comparative situation to what exists on Route 15 North of Leesburg.

The second argument that the special interest groups make is that traffic calming measures similar to those created on Route 50 through Aldie and further westward, when combined with roundabouts, will completely solve the problems on Route 15 North. The problem with their argument and what makes it irrational is simply this – The traffic volume on Route 50 through the Aldie/Middleburg area is less than 10,000 AAWDT. Route 15 North handles 250% more volume!

Even though we have shown traffic calming “solutions” to be completely irrelevant to Route 15 North, we do want to make sure everyone understands what the special interest groups mean when they tout this supposed solution. Traffic calming as the special interest groups envision for Route 15 North includes not only single lane roundabouts (which we’ve already shown will not handle the current traffic volume) but also trees on both sides of the road as well as in a median, even slower speed limits, limited sight lines, and maybe, if they are forced to add them, small grass shoulders rather than paved ones. 

Here is a link to an archive of the website of one group that advocates against widening (site is no longer active):

Notice the picture at the bottom of their page which shows how they envision Route 15 North. It’s pictured here as well.

Although a pretty scene, does this narrow 2 lane road design with trees inches from the edge represent what you think Route 15 should look like? Do you think this design has even a remote chance of providing the capacity increase that we need? Is a tree lined road with no shoulders going to improve safety? The decision is yours.

Stay tuned as we continue our series of informative articles.

Fix Route 15 Now!