Back in 2012, the Northern Virginia Regional Park Authority (NVRPA) commissioned a study of 6 intersections on the W&OD Trail, including specific recommendations for improvements to each intersection. These 6 intersections were chosen based on user input as the ones at which they felt most uncomfortable. They had low motorist yielding rates, high motorist speed and poor sight lines.
Some general recommendations were made for every intersection that include maintaining visibility by clearing vegetation and adding or maintaining lighting. They also recommended widening the trail at intersections to 14-20 feet to allow large groups of cyclists to cross at once, instead of single file.
Then there were a series of Site specific recommendations.
Belmont Ridge Road - I'm going to skip this one because they built an overpass over the trail in 2016.
Sterling Boulevard - The study recommended widening the approach and the median; adding rapid flash beacons instead of signage, improve street and trail marking and shorten the northbound left turn lane so that it starts after the trail crossing. They also recommended completing the sidewalk network there They did all these things in the summer of 2017. (Before shot) In addition, they now want to build an overpass.
Wiehle Avenue - The study recommended widening the median curb, adding a 2nd traffic signal to keep cars stopping at Sunset Hills Road from blocking the trail, changing lane markings and signage and narrowing the road to widen the median. None of these things have been done, but the part of the median where the trail has been upgraded.
Hunter Mill Road - Here there were two recommendations, replace a continuously flashing beacon with an actuated rapid-flashing one and adding an advance yield line to the road. Constantly flashing signs have not been shown to provide consistent yielding by motorists, but rapid-flashing lights have shown a 70%-90% improvement in yielding. These changes have not been made.
Lee Highway - There were a lot of recommendations here, but I'm going to skip those since the plan now is to build a trail overpass.
Columbia Pike - At Columbia pike, they recommended improving the push button crossing buttons; removing the trail stop signs and adding a bicycle signal; implement an LPI; realigning the trail approach; and adding a "right turn traffic yield to bicyclists and pedestrians" sign to Four Mile Run Drive. Since then, some of these things have been (like the trail alignment and removal of the stop sign) and others have not (like installation of a bicycle signal).
Meanwhile and more recently, Loudoun County "Board of Supervisors’ finance committee has endorsed a priority list of safety improvements at W&OD Trail road crossings and recommended that the county start looking for partners to help pay for them"
But in 2016, supervisors asked the county staff and consultants to examine the existing conditions of all 41 W&OD Trail road crossings in Loudoun. From there, they asked for a safety study based on traffic on both the roads and the trail. And now, they are recommending near-term improvements at 12 trail crossings across the county.
The third-highest-ranked priority, the South King Street crossing in Leesburg, has recently seen work by the Town of Leesburg.
A consultant study found the highest-trafficked crossing at Smith Switch Road over the weekend, counting 2,491 trail users on a Saturday in August. Ashburn Road was close behind with 2,309. Bicyclists were the majority of trail users, making up 84 percent of the people on the trail on that Saturday, and three-quarters of people on the trail the following Tuesday.
Those riders would be encountering a VDOT-reported average daily traffic of 2,700 vehicles on Smith Switch, and 8,700 on Ashburn Road.
Although the crossing at South Sterling Boulevard saw slightly fewer trail users in the study, it sees more than twice as much road traffic as the next-busiest road in the study, with an average 27,000 vehicles a day. It also saw by far the highest number of crashes during the yearlong study, with 18 reported incidents. No other crossing reported more than two.
The study also ranked highly the crossings at Hirst Road, Berlin Turnpike, North Hatcher Avenue in Purcellville, Dry Mill Road near Rt. 9, Hamilton Station Road, the Rt. 7 eastbound ramp at Rt. 287, Cochran Mill Road, and Ivandale Road. The Rt. 7 and Rt. 287 intersection is planned to become an interchange, with work starting in 2021
NVRPA has been slowly improving the trail with grade separated crossings since the very beginning. The crossing at Route 28 was built in 1989 and the one at Broad Street some time afterward, for example.
Update: As pointed out in the comments, there are now plans to build a trail overpass at Wiehle by 2021 as well.
The project, which is expected to cost $10 million, aims to address safety concern at the intersection. Changes include a new bridge, retaining walls and directional access to Wiehle Avenue for trail users.
Wiehle Avenue would be widened from Sunset Hills Road to the properties near the Reston Fire Station. The pavement would be widened for on-road bike lanes in the future.
More here at the project website