The document summarizes a study examining existing and future cross-river traffic between Virginia and Maryland across the Potomac River. It analyzed traffic volumes, speeds, and origin-destination patterns at multiple river crossings. Key findings include that interstate highways carry the highest traffic volumes currently, while rail volumes are comparable during peak periods. Speeds varied by crossing and time of day. Origin-destination data showed disbursed trip patterns across the region. Traffic and passenger volumes are forecasted to increase the most by 2040 at more distant crossings. The study developed a common set of data on crossings but did not make recommendations, only defining problems.

1. Potomac River Crossing
Data Development Study
May, 2015

2.  Examine cross-river traffic and movement demand at
existing crossings from Point of Rocks in Virginia to
Route 301 in Maryland
 Develop a common set of data
 DEFINE THE PROBLEM, NOT RECOMMEND THE
SOLUTION
2
Study Background and Objectives

3. REVIEW COMMITTEES
3
Regional Partnership Committee (RPC)
Technical Working Group (TWG)
MDOT Manager, Office of Planning & Capital Programming
SHA Director, Office of Planning and Preliminary Engineering
SHA Division Chief, Office of Planning and Preliminary Engineering
DDOT Manager, Project Review Branch, Policy, Planning & Sustainability Administration
DDOT
Manager, Project Development & Environment Division, Infrastructure Project Management
Administration (IPMA)
MWCOG Four Senior Staff Members
VA-OIPI Deputy Secretary of Transportation
MDOT Director, Office of Planning & Capital Programming
MDOT Manager, Office of Planning & Capital Programming
SHA Deputy Administrator
DDOT Associate Director, Policy, Planning & Sustainability Administration
FHWA Community Planner

4. Study Area and Crossings
4

5. DATA SOURCES
COUNTS
Highway
• A.M. and P.M. Peak Periods, Weekdays, Weekends / by direction
• Existing data from VDOT, MDOT, DDOT if less than 2 years old
• New counts conducted if recent count unavailable
Transit
• WMATA May 2012 MetroRail station-to-station OD summary
5

6. 6
Highway
• Collected for each study area bridge
• TomTom GPS
• Entire 2012 Calendar Year (excluding Nov 17-25 & Dec 22-31)
• Weekday peak period & weekend day
Transit
• 2012 MetroRail Passenger Survey
• Inferred crossing volumes based on shortest station-to-station
pairs
• Patterns reported by direction for peak periods and weekday
FUTURE VOLUMES AND ORIGINS-DESTINATIONS
• MWCOG Travel Demand Model
DATA SOURCES
SPEEDS and ORIGINS-DESTINATIONS

7. 7
INVENTORY OF RELEVANT DOCUMENTS CREATED
• Local Land Use and Transportation Plans
• Relevant Prior Studies of Individual Crossings
DATA SOURCES
OTHER INFORMATION

8. VEHICLES, PASSENGERS AND
SPEEDS AT CROSSINGS
8

9. Daily River Crossings
(Highway Volumes, Transit Passengers
9
0
50,000
100,000
150,000
200,000
250,000
300,000
VehicleVolumeorPassengers
Vehicles Passengers

10. CHARACTERISTICS OF VOLUME DATA
• Vehicle Counts Only
• Vehicle types (autos / trucks / buses) not identified separately
• Vehicle occupancies (SOV / HOV) not identified separately
• Types and occupancies likely vary by bridge
• Transit passengers estimated from WMATA on-board survey
• (Counted) roadway vehicles compared with (estimated) transit
passengers
10

11. Speed Data Example
11
Weekday AM Peak:
Tue/Wed/Thu,
06:00-09:00
Weekday PM Peak:
Tue/Wed/Thu,
15:00-19:00
Weekend:
Sat/Sun,
00:00-24:00
Weekday AM Peak:
Tue/Wed/Thu, 06:00-
09:00
Weekday PM Peak:
Tue/Wed/Thu, 15:00-
19:00
Weekend:
Sat/Sun,
00:00-24:00
362 637 2,440 343 1,022 2,076
Average 51.2 50.4 49.2 49.5 47.5 48.5
Median 51.9 51.3 50.5 50.3 48.7 49.6
5th percentile 60.2 58.8 59.3 58.1 56.7 57.7
10th percentile 58.2 56.9 57.3 56.5 54.6 55.6
15th percentile 57.0 55.7 56.0 55.1 53.7 54.4
20th percentile 56.0 54.8 55.0 54.1 52.5 53.4
25th percentile 55.1 54.0 53.9 53.2 51.7 52.7
30th percentile 54.4 53.3 53.3 52.7 51.0 52.0
35th percentile 53.8 52.8 52.5 52.0 50.5 51.4
40th percentile 53.1 52.2 51.9 51.4 49.9 50.7
45th percentile 52.5 51.6 51.1 50.8 49.2 50.2
50th percentile 51.9 51.3 50.5 50.3 48.7 49.6
55th percentile 51.3 50.6 49.8 49.6 48.1 48.9
60th percentile 50.7 50.0 49.3 49.0 47.5 48.2
65th percentile 50.2 49.3 48.4 48.5 46.5 47.6
70th percentile 49.5 48.7 47.7 47.7 45.8 46.8
75th percentile 48.7 48.0 46.7 47.0 44.9 46.0
80th percentile 48.1 47.1 45.7 46.2 44.0 45.0
85th percentile 47.1 46.0 44.3 45.3 42.6 43.8
90th percentile 45.6 44.8 42.5 43.8 41.2 42.4
95th percentile 43.7 42.7 39.3 41.0 38.6 40.1
Sample size
TravelSpeed(mph)
Crossing Name Gov Nice Bridge Eastbound Gov Nice Bridge Westbound
Covered Route Length 2.03 mile 2.03 mile
Time Groups

12. Ratio of Average Speed to Speed Limit
P.M. Peak Period
12
-
0.20
0.40
0.60
0.80
1.00
1.20
1.40
RatioofAverageSpeedtoSpeedLimit
PM Peak Eastbound (from VA) PM Peak Westbound (to VA)

13. CHARACTERISTICS OF SPEED DATA
13
• Comparison to Posted Speed Limit - One of many ways to
evaluate (roadway) performance
• Does not reflect
• Number of passengers / (different) roadway volumes
• Level of congestion
• Person-hours of delay
• Etc.
• Applying different measures will produce different results

14. TRAVEL PATTERNS AT
CROSSINGS
14

15. 15
District Boundaries for O-D Data

16. District Boundaries for O-D Data
Washington D.C. and VA-MD-WVa
16

17. Example Origin-Destination Table
Existing Trips - Memorial Bridge
WB PM Peak Period
17
* Highlighted cells indicate greater than 5% of trips.
Destination District
Origin District
(see detailed map)
Arl. Co.
Fx. E. of
I-95
SE Fx
(w. of
I-95)
SE
Pr.Wm.
ALX
18 22 23 26 31 Subtotal
DC Core 14 16.7% 6.6% 7.4% 6.7% 14.4% 51.7%
NW Washington DC 15 2.0% 1.5% 2.5% 0.7% 2.3% 9.0%
Subtotal 18.7% 8.1% 9.9% 7.4% 16.7% 60.8%

18. CHARACTERISTICS OF
ORIGIN - DESTINATION DATA
18
DATA REPRESENTS THE MOST ROBUST SOURCE OF O-D
DATA OF POTOMAC RIVER CROSSINGS EVER COMPILED
• Total Highway (GPS) observations = approx. 300,000
(entire 2012 year)
FACTORS TO CONSIDER IN INTERPRETING THE DATA
• Travel date unknown
• May include repetitive users (same trip every day)
• Does not include travelers who do not use GPS
• May not reflect original origin and ultimate destination (trip
interruptions)

19. FORECASTED CROSSING
CONDITIONS
19

20. Total Daily Volumes on Crossings
20
0
50,000
100,000
150,000
200,000
250,000
300,000
Point of
Rocks
Legion Chain Key Roosevelt Memorial 14th Street Wilson Nice Metro
Rosslyn
Metro
Fenwick
VRE
Existing 2040
Vehicles Passengers

21. Example Origin-Destination Table
2040 Forecasted MetroRail Trips
Rosslyn Tunnel (Orange/Blue/Silver Lines)
21
Fraction of Forecasted Observations
Trip Percentages Destinations
Origins
FarragutWest
FederalTriangle
FoggyBottom-GWU
JudiciarySquare
L'EnfantPlaza
McPhersonSquare
MetroCenter
GrandTotal
3 1.36% 0.28% 1.06% 0.48% 0.50% 1.18% 0.47% 5.34%
18 2.86% 0.55% 2.52% 0.90% 0.93% 2.44% 0.92% 11.13%
23 1.81% 0.27% 1.41% 0.45% 0.45% 1.55% 0.54% 6.47%
33 1.23% 0.24% 0.92% 0.45% 0.44% 1.05% 0.43% 4.75%
Grand Total 7.27% 1.34% 5.91% 2.27% 2.32% 6.22% 2.36% 27.69%
* Highlighted cell indicates greater than 5% of trips for total origins
or destinations or greater than 2% of trips for O-D pairs.
Origin
District
(see map)
Northeast Fairfax
Arlington
South-Central Fairfax
Northwest Fairfax

22. SUMMARY OF FINDINGS
22
• Vehicle counts only (not passengers) on highway bridges
• Interstates (except Roosevelt) carry highest volumes; Other bridges
carry generally comparable volumes (except Roosevelt). Roosevelt
volumes are between Interstates and other bridges
• Metrorail volumes comparable to Interstates in Peak Periods
• Speed vs. Speed Limit: One of many ways to evaluate (roadway)
performance; Applying different measures will produce different results
• Bridges serve different markets; O-D patterns widely dispersed
• Volumes and passengers forecast to increase by 2040; % Growth
greatest on more distant bridges

23. THANKS!
Questions / Comments