The I-395 Express Lanes North Extension Environmental Assessment (EA) lists roadway safety as one of four principal objectives in extending I-395 toll lanes north to Eads Street (p. 6). It cites the fact that over half of all roadway crashes occur during peak travel periods to demonstrate that congestion not only increases travel time, it also jeopardizes traffic safety (p.14).
VDOT’s concern with roadway safety is well placed. However, it is by no means clear that HOT lanes will enhance travel safety even if they reduce congestion, since the Build Alternative all but eliminates the western shoulder of the express lane corridor by reducing it from 10 feet to 2.
According to VDOT:
Disabled vehicles and emergency responders would use the east side of the corridor during emergency situations. The easternmost travel lane (11 feet wide) along with the eastern shoulder (generally 10 feet) would provide a 21-foot wide travel way which would be sufficient for the emergency vehicles to access incidents along the corridor.
The EA notes that:
the Build Alternative was developed using current design guidelines, including the American Association of State Highway and Transportation Officials (AASHTO) A Policy on the Geometric Design of Highways and Streets, 2011 (Green Book) and the VDOT Road Design Manual (April, 2016)
and that the Technical Working Group (TWG) reached consensus on the design.
If the TWG reached consensus, it did so by disregarding interstate highway standards not adhering to them. According to FHWA publication “Mitigation Strategies For Design Exceptions”:
The adopted shoulder criteria for Interstates specify that:
the paved width of the right shoulder shall not be less than 10 feet (3.0 meters). Where truck traffic exceeds 250 DDHV (the design hourly volume for one direction), a paved shoulder width of 12 feet (3.6 meters) should be considered. On a four-lane section, the paved width of the left shoulder shall be at least 4 feet (1.2 meters). On sections with six or more lanes, a 10-foot (3.0-meter) paved width for the left shoulder should be provided. Where truck traffic exceeds 250 DDHV, a paved width of 12 feet (3.6 meters) should be considered.
This makes sense. Emergency vehicles might be able to access disabled vehicles after the fact, but the lack of a shoulder on one side means that disabled vehicles in the far lane will have no place to go and therefore induce crashes. That coupled with information in EA Table 1-1 (p.16) that injury rates are higher in the existing express lanes—undoubtedly because of higher speeds—will make travel in I-395 express lanes more hazardous especially during peak periods.
VDOT should examine another alternative, namely conversion of the existing two HOV lanes to HOT lanes without the third express lane. If that dog won’t hunt, then scrap HOT lanes and promote transit in the I-395 corridor instead.