Annandale Transportation Study - Fairfax County Office of ...

Annandale Transportation Study – Final Report
3. TRANSPORTATION NETWORK ALTERNATIVES
3.1. Networks Evaluated
Based on the previous transportation and land use studies for the Annandale CBC, nine transportation future
condition networks were selected for detailed microsimulation analysis using the same models and methodologies
used to evaluate existing conditions.
With the exception of Network 0 (No-Build) all of the alternatives included most if not all of the following transportation
improvements recommended in the Comprehensive Plan for Fairfax County:
a) Widen Little River Turnpike to six lanes through the Annandale CBC.
b) Improvements to Annandale Road to upgrade to a continual four-lane roadway with turn bays at signalized
intersections, including improvement of the horizontal alignment of Annandale Road north of Little River
Turnpike.
c) Construct overpass that would take Annandale / Ravensworth over Little River Turnpike.
d) Closure of Little River Turnpike / Columbia Pike intersection; the current one-way section of Columbia Pike
between Little River Turnpike and Backlick Road will be converted to two-way.
e) Realignment of Columbia Pike with Backlick Road including the realignment of Columbia Pike to intersect
Poplar Street; the Maple Place / Columbia Pike / Backlick Road intersection is reconfigured to make Columbia
Pike to Backlick Road the dominant through movement.
f) Consolidation of access and removal of service drives along Columbia Pike where sufficient inter-parcel
access can be provided.
g) Construction of a roundabout at the intersection of Maple Place at Martin Avenue.
h) Extension of Poplar Street west of Daniels Avenue to Columbia Street, creating a new intersection with Tom
Davis Drive.
i) Completion of the Southern Loop including improvements to Markham Street (south of Little River Turnpike) /
McWhorter Place roadway connection to John Marr Drive.
One additional change to the network was made to define the recommendation in the Comprehensive Plan to close
Columbia Pike at Little River Turnpike and to establish the Backlick Road to Columbia Pike (north of Maple Place)
connection as the dominant through movement. A concept was developed to place a dual-lane roundabout at the
Columbia Pike / Backlick Road / Maple Place intersection allowing a better north-south movement connection,
particularly in the northbound direction by creating a separate, exclusive lane so that northbound vehicles can by-pass
entering the roundabout. This proposed configuration, identified in Figure 9, also provides better access to the
properties in the section of Columbia Pike between Little River Turnpike and Maple Place after the intersection at
Little River Turnpike is removed.
The proposed roundabout design provided better intersection operations than a conventional signalized intersection
as the potential for queuing in the northbound direction is reduced and access to Columba Pike to the south is
improved. The roundabout concept was evaluated in all the alternative networks. A signalized intersection that
provides adequate capacity could be proposed as an alternative when intersection improvements are to be
implemented.
With the addition of the Backlick / Columbia Pike / Maple Place roundabout into the network analyses, the Maple
Place / Martin Avenue roundabout (currently in the Comprehensive Plan) becomes of lesser importance. Analysis
results indicate the Maple Place / Martin Avenue intersection would have acceptable intersection operations as an
unsignalized intersection. Further study, concept design and analysis are needed to determine if the proposed new
roundabout precludes (due to close proximity) the roundabout at Maple Place included in the Comprehensive Plan.
FIGURE 9: Conceptual Backlick / Columbia Pike / Maple Place Roundabout
The nine transportation networks that were evaluated using microsimulation are identified in Table 6. The network
alternatives assumed the aforementioned Comprehensive Plan base conditions with the noted changes to the number
and arrangement of lanes on Little River Turnpike and the condition with and without the Annandale/ Ravensworth
overpass.
TABLE 6: Transportation Network Alternatives Evaluated using Microsimulation
Network 0
Network 1
Network 2
Network 4
Network 4a
Network 5
Network 6
Network 7
Network 8
No improvements to the current transportation network
Only the Comprehensive Plan improvements
Comprehensive Plan (Network 1) WITHOUT Annandale Road overpass
Comprehensive Plan EXCEPT 4 lanes on Little River Turnpike
Comprehensive Plan EXCEPT 4 lanes on Little River Turnpike and WITHOUT overpass
Comprehensive Plan WITHOUT overpass and one-way pair on LRT / south loop between John Marr
Drive and Markham (3 WB lanes on LRT, 3 EB lanes on south loop)
Comprehensive Plan WITHOUT overpass and 4 lanes on LRT PLUS one-way pair using both north and
south loops between John Marr and Markham (2 WB lanes on north loop and 2 EB lanes on south loop)
Comprehensive Plan WITHOUT overpass and 3-1 pair on LRT / south loop between John Marr and
Markham (3 WB & 1 EB lanes on LRT, 3 EB & 1 WB lanes on south loop)
Comprehensive Plan WITHOUT overpass, with median U-turns in a wide median along the LRT corridor
between Hummer/Heritage and Evergreen Lane; replaces existing service drive
April 2010
15