TPB has written up a
short study of traffic conditions on the day of the Metro shut down last month. The study compared traffic conditions on that "shutdown" day (3/16) to conditions on the previous Wednesday (3/9), considered a "typical" Wednesday. Here's a quick synopsis of key points:
- Overall, traffic conditions on shutdown day were slightly worse than normal, although there are notable geographical differences. Traffic was overall worse in the "regional core" (defined as DC, Alexandria, and Arlington County), but better overall in the suburbs.
- Inside the Beltway, the major inbound freeways all experienced negative impacts during the morning peak (defined as the 7am hour), with the biggest impacts being on northbound I-395 and I-295. The inbound HOV facilities (I-66 and the I-395 HOV lanes) saw slight degradation, but not nearly to the extent that the mainline freeways and other facilities (i.e. GW Pkwy) saw.
- Outside the Beltway, the only inbound freeway to see a negative impact during the morning peak was I-270, likely a result of losing the Red Line from Shady Grove south. Other inbound freeways generally held steady, although a few (namely I-95, I-66, and the DTR in Virginia, and US 50 in PGC) saw improvements over normal morning peak traffic.
- The study didn't specifically discuss the Beltway, although looking at the attached traffic maps, there didn't seem to be a significant change overall during the morning peak. Traffic appeared worse on the Inner Loop through Tysons and on both sides through Largo, but better on the Inner Loop through MoCo.
- The evening peak (defined as the 5pm hour) was a very different story. As a general rule, evening traffic on shutdown day was far lighter than normal. The study suggests two possible reasons for this: A) workers and commuters adjusted their departure times to avoid the peak, thereby spreading traffic out, and/or B) people took fewer discretionary trips in the evening, which had the effect of reducing traffic. Either way, regionwide traffic was down 4% compared to normal.
- As opposed to the morning peak, the core jurisdictions saw the most improvement over normal during the evening peak, and Fairfax County also saw a significant reduction compared to normal. As a general rule, the inner jurisdictions saw reduction while the outer jurisdictions saw little or no change compared to normal.
- Most outbound freeways, both inside and outside the Beltway, saw reductions in travel times compared to normal. Those that didn't see a reduction had little or no change from normal. The biggest reductions from normal were on I-295 and I-395 inside the Beltway, and on I-66 outside the Beltway.
- Comparing the traffic maps, the Beltway appears to have had overall improvement as well, particularly at the Wilson Bridge approaches (both sides), the Outer Loop through PGC, and the Inner Loop from Tysons to 270. Other areas of the Beltway appeared to have no change compared to normal during the evening peak. Notable congestion remained on the Outer Loop from MoCo to Tysons, the Inner Loop through MoCo and from Greenbelt to Largo, and the Outer Loop south of Tysons. The Inner Loop from Largo to Andrews appears to have been worse than normal.