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By Robert Thomson  |  May 11, 2009; 9:24 AM ET
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Submitted this to the discussion as well, but want to make sure it's read by all.

The following is from the Herrity Report from Supervisor Pat Herrity's office:

New FHWA decision delays extended use of Monument Drive and Stringfellow Road I-66 Slip Ramps

If you have read previous issues of the Herrity Report, you may recall I have been working with the Virginia Department of Transportation (VDOT) to have the I-66 HOV slip ramps at Monument Drive and Stringfellow Road opened for use outside of HOV hours. Placing a hurdle in the way of my continued pursuit of short term solutions to mitigate congestion on I-66, one of our region's worst corridors, the Federal Highway Administration recently determined that our request to use the ramps outside restricted time periods will require an Interchange Modification Report (IMR). What this means is that instead of a simple change in signage, FHWA is requiring VDOT to treat each of the ramps in this proposal as a new interchange, requiring new studies for each. In other words, FHWA has placed us back at the start.

Both VDOT and I are disappointed in this finding because the of the proposal's merit in terms of safety and mobility. VDOT has promised me it will continue to pursue the proposal as long as it's practical. VDOT's administration is exploring various options to further discussion with FHWA while VDOT staff will assess the IMR to determine the likelihood of a successful outcome. In addition I have requested support from Congressman Frank Wolf who is supportive of both of these efforts. I will continue to push for a positive outcome to this proposal.


I've also been monitoring this for the past 15 months. Opening these two ramps would make A LOT of peoples lives better as it would decrease traffic on 50, 7100 and 28 by giving alternative access points to/from 66 for folks living along the Monument Drive/Stringfellow Road corridors.

Why hasn't this been covered in the Washington Post? I'm a somewhat regular reader of the paper and follow the transportation columnists/blogs, yet I don't recall this being covered. Can you (and your colleagues) please cover this so that those folks at FHWA don't lose sight of the importance of this interchange?

This could've been done rather quickly for a rather paltry amount of money (the infrastructure is already there, only signage, light metering would need to be changed), but instead, gov't got their hands in the works and gummed it all up. C'mon folks, let's not make "Yes, we can!" to "Well, maybe we should study this thing to death."

Yeah, I'm not disgruntled or anything.

Posted by: SamFelis | May 11, 2009 10:30 AM | Report abuse

IMR's are required for any modification to interchanges along the US Interstate Highway system, according to FHWA rules. This is not a requirement for just VDOT or just this project, but this is a requirement for everyone. It was certainly worth their while for VDOT to ask FHWA for an exception, but by FHWA not granting it, they are not being mean, they are simply asking VDOT to follow the procedure that any other state has to follow in order to modify an interchange along the interstate highway system.

I think opening up the ramps for longer hours is a good idea, but definitely not one that should be considered without some study and evaluation of alternatives. It is not as simple as just flipping a switch. Here's a summary of what I would consider FHWA's concerns with just opening up those ramps tomorrow. I do not work for FHWA, nor have I seen any data for this specific project, so these are simply my own thoughts.
1) Those ramps enter/exit on the left. Currently, FHWA only allows exit and entrance ramps on the right, as having entering/exiting traffic coming into/out of the passing lane is dangerous. The only standard exception to this is ramps merging into/out of an HOV lane on the left, where the benefit of allowing HOV traffic to merge directly into the HOV Lane instead of cutting across the normal lanes outweighs the concerns of the left entrance/exit. During HOV hours, that ramp is an HOV entrance/exit. Outside of HOV hours, it is just a plain old exit/entrance on the left into the passing lane.
2) Those two interchanges, in their current configuration, cannot support traffic in both directions at the same time. At Monument Drive, there is only a double yellow line seperating the entrance lane and exit lane, and physical seperation of the ramps would be required. At Stringfellow, there isn't even a double yellow line on the entire ramp, because the ramp is not wide enough for two full lanes.

Posted by: thetan | May 11, 2009 11:51 AM | Report abuse


3) The ramps were only designed to carry a certain amount of traffic. If the ramps are open during HOV hours, the traffic counts are held down by the HOV requirement. If the ramps are open without any HOV restrictions on them, then the traffic counts are likely to be higher than rush hour volumes. Think of I-66 in Arlington...more traffic during non-HOV hours than when restricted. It is quite possible that the amount of traffic that would use it during non-HOV hours would exceed the design capacity of the ramp.
4) The traffic signals at the end of the ramp operate as two-phase signals. In the AM peak hour, there is one phase for through traffic on the local road, and one phase where southbound traffic can turn left onto the ramp. In the PM peak hour, there is a phase for the local road, and a phase for the ramp. If the ramps were opened to traffic both ways all the time, the signal would be required to switch to 3-phase operation, since there would need to be a phase for the local road, a phase for southbound left turns, and a phase for the ramp. Three phase signals are not as efficient as two phase signals. There is a chance that the signal would become overloaded with 3 phase operation, and would have traffic backing up onto I-66.

We can't know the extent of any of those problems without conducting a traffic study (IMR). The IMR can actually help the cause, because if any of those issues do come up, the IMR can suggest solutions, rather than having FHWA deny the request outright. Such solutions could include building a jersey wall barrier down the center of the ramp for positive physical seperation, only operating the ramps in one direction (say, eastbound entrance during AM hours, westbound exit during PM hours), extending the hours of operation of the ramps without going to full-time operation (open them when they would provide traffic relief, but at some times there might be sufficient capacity on 50, 7100, etc. such that the ramps are not needed all the time), opening the ramps but restricting them to HOV-traffic at all times, having FHWA mandate that the ramp gets a minimum percentage of green time so traffic does not back up onto the highway...and probably many more ideas that I haven't come up with.

Posted by: thetan | May 11, 2009 11:58 AM | Report abuse

@thetan - While your points are valid and reasonable re: the IMR and design of the ramps, what I find unreasonable is that this has been going on for over 15 months. I contacted VDOT in January 2008 and asked about the ability to open these exits up. At that point, VDOT were working with FHWA on signage issues and hoping to have the ramps open "sometime soon".

If the FHWA was going to reject the design issues in favor of conducting IMRs, they should have done so then, vs. waiting another year before saying...."whoa, let's start this whole thing over from scratch."

It's for THAT reason, and that reason alone, why I'm calling FHWA on the carpet. They wasted a over a year in making this determination when they could've been working on it from the start.

If they were my employees, they'd be fired.

Posted by: SamFelis | May 11, 2009 1:47 PM | Report abuse


Have you considered that perhaps what VDOT was telling you was completely different from what VDOT was telling FWHA? Or that what VDOT was telling YOU was a load of crock?

Posted by: ceebee2 | May 11, 2009 2:03 PM | Report abuse

Interesting. I'm not sure why FHWA didn't insist on the IMR right away, it seems that is what should have been done. IMR's aren't produced overnight, but they should be able to get one done in much less than 15 months.

If it were up to me, I'd open them up as entrance ramps from 5AM to noon, and exit ramps the rest of the day, and all-day on weekends. This ensures that there is never 2-way traffic on the ramps, uses them as left exits, which is the lesser of two-evils when it comes to left entrances/left exits, and allows them to be used in both directions by rush hour commuters. I would open them to all outside of HOV hours, but only on a trial basis, to gauge how well they would be utilized, with the stipulation that if too many are using them such that traffic backs up onto the highway, than HOV-2 only all times. I'd probably adjust the signal timing throughout the first week to make sure it is working optimally. Oh well, too bad I'm not King :)

Posted by: thetan | May 11, 2009 2:07 PM | Report abuse

About using the left lane for passing only...the referenced situation was I-66 in Centreville, which has HOV lanes. HOV lanes throw the whole "left lane for passing only" out the window, since those with 2 people will gravitate towards that lane, and those with only a driver cannot use it. It is almost as if the HOV lane is a seperate roadway. However once HOV restrictions expire, that lane is simply the left lane of the highway, and should be used as a passing lane only.

Posted by: thetan | May 11, 2009 2:11 PM | Report abuse

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