Friday, March 11, 2016
W&OD Trail bridge at Wiehle Ave - Public Hearing March 17
|Design concept 1|
The Wiehle Ave crossing has been the site of several bike crashes in the past. This bridge will allow cyclists to completely bypass the at-grade crossing. Access to Wiehle Ave from the W&OD Trail will be via paved side trails from east and west of the bridge.
Two engineering concepts have been developed that vary according to the slope of the bridge, either 3% or 5%. With the 3% slope the approach to the bridge would be easier to climb, but the access trails to reach Wiehle would be long. The 5% slope (or grade) would have a shorter, steeper approach to the bridge and as a result, the access trails will be shorter.
The W&OD Trail bridge over Herndon Parkway (on the east side of Herndon near the police station) has about a 5% grade when approached from the west. The Town Center Parkway bridge has about a 3% grade (at least according to my iPhone app TiltMeter).
The bridge will cross Wiehle where the gravel trail currently crosses. The current paved trail will serve as the access trail to/from the W&OD Trail to Wiehle Ave. With the 3% grade concept, because the bridge and supporting structure are longer, the access trails are longer and join the W&OD Trail near the Isaac Newton Square/Metro Center Dr intersection and the Michael Faraday Dr intersection. With the 5% grade concept the access trails join the main W&OD Trail midway between those two intersections (This is difficult to describe. See the full pdf design concept for 3% grade and 5% grade for details).
Below are excerpts from the design drawings and the conceptual rendering from street level, looking north from Sunset Hills Dr.
|Bridge location at Wiehle Ave|
|Access trail converges with main trail|
at Isaac Newton Square near Metro Center Dr
|Design concept 2|
|Design concept 3|