An endless river of rush hour traffic in Tysons. Image by Daniel Kelly licensed under Creative Commons .

As a Northern Virginia resident living in Alexandria/Fairfax, I experience the effects of limited transit options and historical transportation planning decisions on a daily basis . The time it takes to drive from the I-95/395 Mixer to my offramp in Alexandria is frequently long, due to severe congestion on I-495 in the afternoon rush hour.

As local communities and agencies grapple with congestion and transit limitations in our region, we have to make tough choices about our collective future that are difficult to reverse and require large investments over many years. I would argue that we need to build a rapid transit route between Tysons Corner and the denser communities along the southern beltway, carrying people to Alexandria and Counties in Maryland. A kind of Purple Line South, or something similar.

The alternative to new transit is yet more freeway lanes. “Build it and they will come” applies as much to additional freeway lanes as to an amusement park. We are again in the process of considering more lanes on I-495 through the Wilson Bridge. What you can bet on is that adding them will be a short term fix before the congestion returns.

The out-of-control congestion on the Southern Beltway in Virginia towards the Wilson Bridge needs a long term solution. Many clamor for new highways and the I-495 Southern Beltway study has been looking at additional express lanes from the Springfield interchange (The Mixer) to Maryland. However, by the time these new lanes open, we will need to be planning the next addition.

A simple analysis of traffic patterns on the southern beltway reveals the origins of the congestion at the Wilson Bridge and why it’s likely to get worse. Using data analysis, we can see that a very large concentration of vehicles originates from destinations along the Beltway in Virginia. My colleague, Leda Hinkle, produced maps to illustrate the point. The darker colors indicate the zip codes where more vehicles on I-495 start their journey. The zip code areas in lighter colors have fewer vehicles heading down I-495.

Map of I-495 traffic origin points. Image by the author.

Looking at these zip codes in the darker colors, around forty percent of the afternoon rush hour traffic on 495 heading towards Maryland appears to be coming from Tysons, Mclean, Vienna, Merrifield, Mantua, West Falls Church, Mosby, Annandale, Wakefield, North Springfield, Lincolnia, Bren Mar Park and West Alexandria.

Those vehicles head for places in Maryland, predominately in Prince George’s or Charles counties, areas like Oxon Hill, Temple Hills, Forest Heights, Ft Washington, Suitland, and Clinton.

Map of destinations of 495 Beltway traffic in the afternoon. Image by the author.

If that is your commute, there are limited Transit alternatives that make any sense. Just try taking a trip from Oxon Hill to Tysons Corner via transit during peak hours. It’s not fun. Google recommends buses 35 or D12 from Oxon Hill to Metro Southern Avenue Station, then the Green Line to L’Enfant and Silver Line to Tysons. That’s about one hour thirty or two hours, with two vehicle changes!

What is the solution?

As reported by GGWash , in 2011, WMATA studied a “metro loop” to help address the problems I described earlier. The study found that it reduced congestion on the Metro for all current routes in 2040 except for the Yellow line. This would significantly increase connectivity and access to jobs, shopping, entertainment venues, and housing for those across the DC region and around the Beltway. Most importantly, this would reduce congestion on the southern beltway.

The I- 495 study has a transit component that examines express and commuter bus options. Some of these buses would operate in the proposed express lanes in mixed traffic with cars, trucks etc.

When the Wilson Bridge was originally built, it included two lanes for “ HOV/express bus/rail transit lanes ” and the design had to include two lanes for future Metro transit lines. Official documents indicated that this transit line would reduce traffic by 1,500 vehicles per day with an express bus service, or 3,500 vehicles per day with a metro rail line by 2020.

So the question arises: Do we need a rapid transit line to roughly follow the beltway, a new Bus Rapid Transit(BRT), a southern light rail system, or new bus routes? Various s tudies have shown that rapid transit lines do in fact have an impact on congestion if they are not in mixed traffic. However, the hub-and-spokes model of Metro will not be sufficient for future growth.

Transit speed is a key factor to consider.

Average speed of Bus Rapid Transit (BRT) Buses, Light rail, or Metrorail Image by the author.

The Metro 2019 Blue/Orange/Silver Capacity and Reliability Study recommended future rail transit options. “The Bloop”, or blue loop option for a new rail route on the Metro seems to be the most popular and designed to cross the Potomac on the Wilson bridge too!

With Metro looking at the Bloop, it does seem that there is merit in planning for a southern Metro Line or Southern Purple Line around the beltway into Maryland. It will be costly, but its impact will be large and will last, because of the vast potential ridership numbers. (We would need to allow some densification around the new stations).

The Bloop and a Southern Metro Line/Purple Line could share those two lanes on the Wilson Bridge. However, if we give those center lanes on the Wilson bridge over to cars and trucks, can any of us imagine elected officials in the future voting to remove those cars and to install transit?

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Ian Ollis, AICP, is a transportation planner and head of the Fredericksburg Area Metropolitan Planning Organization. He is resident of Alexandria/Fairfax and has no dogs. He writes in his personal capacity.