🚀 go-pugleaf

Here's a success story here in the Washington D.C. metropolitan area.  A
report of Interstate highway HOV facility performance was just released
for the Washington D.C. metropolitan area:

_1997 Performance of Regional High-Occupancy Vehicle Facilities on
Interstate Highways in the Washington Region, An Analysis of Person and
Vehicle Volumes and Vehicle Travel Times_, May 20, 1998, by Metropolitan
Washington Council of Governments (COG), National Capital Region
Transportation Planning Board (TPB)

There are three Interstate HOV corridors in operation as of Fall 1997 in
the Washington region:

** I-95/I-395 (Shirley Highway) in Northern Virginia **
This highway has a 27-mile barrier-separated HOV-3 reversible 2-lane
roadway from south of VA-234 at Dumfries in Prince William County to
South Eads Street near the Pentagon in Arlington County.  The north end
of the reversible roadway divides into 1.5 mile of conventional 4-lane
divided express lanes (not HOV presently) that cross the 14th Street
Bridge into D.C. and merge into 14th Street and the I-395 Southwest
Freeway.

** I-66 in Northern Virginia **
This highway has 18 miles of an HOV-2 inner diamond lane each way from
west of VA-234 at Manassas to I-495 Capital Beltway, and 9.6 miles of
2-lane exclusive HOV-2 in peak hours in peak direction, from I-495 to
Rosslyn.  I-66 from Rosslyn, across the Theodore Roosevelt Bridge, to
its terminus in D.C. (about 1.5 mile) does not have HOV facilities. 
Dulles Airport SOV traffic can use the highway at all times from Rosslyn
to the Dulles Airport Access Road.  The eastern 3 miles of the DAAR is
part of this HOV facility.

** I-270 (and I-270 Spur) in Montgomery County, Maryland ** 
This highway has 18 miles of an HOV-2 inner diamond lane each way from
MD-121 at Clarksburg to I-495 Capital Beltway. 

The report is large and very detailed, and a copy would be beneficial
for interested parties.  Detailed traffic data gathering was performed
over a long period of time, and detailed data analysis was performed to
produce the report.  There are many tables.  

Here's some summary excerpts:

"All of these HOV facilities are currently operating at a high level of
service, and providing substantial time savings relative to alternative
LOV facilities.  Expressed on a per-mile basis, the savings range from
approximately 0.5 minutes per mile to just over 1.4 minutes per mile. 
For travelers making use of the full length of these facilities, the
savings range from 5 to 12 minutes on I-270, from 17 to 28 minutes on
I-66, and from 34 to 39 minutes on I-95/I-395".

"In general, the movement of persons per lane per hour is significantly
higher in HOV lanes than in non-HOV lanes.  HOV lane person movement
ranged from 2,200 to 4,700 per lane per hour while non-HOV lane person
movement ranged from 1,400 to 2,000 persons per lane per hour".

"High-occupancy vehicle (HOV) facilities can:  increase the number of
persons per motor vehicle using a highway over conventional (non-HOV)
lanes or roadways; preserve the person-moving capacity of a lane or
roadway as demands for transportation capacity increase; enhance bus
transit operations; support air quality goals; serve a variety of
employment centers in urban and suburban areas; and provide predictable
travel times even during periods of high demand for highway capacity".

This is an interesting report.  All three of these radial expressways
have long-established alignments, over 35 years in each case.  Each had
HOV facilities added to an existing expressway (except for the special
case of multi-modal I-66 inside the Beltway).  They are diverse in
characteristics, with two expressways (I-95/I-395 and I-66) reaching the
D.C. urban core, and one (I-270) with its inbound terminus at the
Capital Beltway.  The entire I-95/I-395 HOV facility is
barrier-separated with direct ramp access.  I-270 is entirely a
concurrent-flow (diamond lane) design.  I-66 is part concurrent-flow and
part barrier-separated (by default) HOV design.

My analysis is that future metropolitan growth can lead to even higher
person volumes per lane per hour.  Originally, the Northern Virginia
facilities, I-95/I-395 throughout and I-66 inside the Beltway, had HOV-4
restrictions, and these were eased when it was found that congestion
would not result.  Heavy peak period HOV traffic increases would lead to
increasing the HOV threshold, and obviously an HOV-4 lane near vehicle
capacity would carry a lot more people than an HOV-2 lane near vehicle
capacity.  So these HOV lanes seem to have a bright future.  The Dulles
Toll Road HOV-2 concurrent-flow (diamond) lanes will open late this
year, and will bring increased HOV traffic to I-66 east of the DAAR
interchange.

There seems to be enough diversity here to conclude that expressway HOV
lanes can be a successful development in many large metropolitan areas. 
The Washington D.C. area has 4.6 million population.

Note about the author agency - 
"The Metropolitan Washington Council of Governments is the regional
organization of the Washington area's major local governments and their
governing officials.  COG works toward solutions to such problems as
growth, transportation, inadequate housing, air pollution, water supply,
water quality, economic development, and noise, and serves as the
regional planning organization for Metropolitan Washington".

-- 
Scott M. Kozel     Highway and Transportation History Websites  
Virginia/Maryland/Washington D.C. http://www.richmond.infi.net/~kozelsm
Philadelphia and Delaware Valley
http://www.geocities.com/CollegePark/Campus/5961/pennways.html