Meadowcreek Parkway Interchange panel hears cost estimates for bridge
Artist’s conception of Alternative C1 with further refinements
The panel guiding the design of an interchange for the Meadowcreek Parkway and the 250 Bypass held its tenth steering committee meeting on August 16, 2007. Members were briefed on the progress of the Project Team’s work refining various options, and were asked to consider design priorities for the large bridge that will carry the 250 Bypass over top either an oval roundabout (Alternative C1) or a signalized intersection (Alternative G1).
Owen Peery with the consulting firm
said the Project Team has made several adjustments to the design since July when the
City Council approved two interchange alternatives
as being consistent with the City’s Comprehensive Plan.
At-grade crossings for pedestrians moving north-south have been eliminated, in favor of underpasses that go below the on-ramps to the oval roundabout. The north-south multi-use trail will now definitely travel along Schenck’s Branch. A pedestrian bridge has now been designated to cross the parkway north of the interchange, rather than across the 250 Bypass. Peery suggested construction of this bridge might be built later than the rest of the project in case the overall cost exceeds the funding available.
Similar refinements were made for Alternative G1, which is being refined as a second option without a roundabout.
The steering committee also heard about a July 30 traffic summit between the design team and VDOT engineers. RKK is preparing a report for the Federal Highway Administration to demonstrate how it is arriving at its traffic figures for modeling purposes. At issue is whether RKK can continue to use traffic models which assume no significant improvements to Free Bridge (and no improvements are planned), constraining the amount of traffic that can get to the interchange in a given hour.
If Alternative C1 is selected, RKK recommends building a multi-lane roundabout in order to accommodate future traffic.
RKK Traffic Engineer Jeff Parker says VDOT remains concerned with a traffic weave that will be required for traffic getting onto Route 250 from the roundabout. VDOT also wants to know how the interchange will affect the Park Street interchange to the east, and how that exit could be refined accordingly. The project team will evaluate options to update Park Street to a signalized interchange to control flow on and off of the 250 Bypass
Peery said more detailed planning work can be done once a bridge alternative is selected because that will give engineers a height from which to work. He said a lower height is preferred, because it will keep the costs down.
“It’s still a moving thing here, but we think we’re honing in on where we want to be,” Peery said.
The Vietnam Veterans’ Memorial will be affected by the Meadowcreek Parkway Interchange
Angela Tucker of the City’s Neighborhood Development Services Department is the staffer coordinating the project on behalf of Charlottesville. She briefed members of the steering committee on an August 13th meeting with project team members and representatives of the Vietnam Veterans Memorial.
Tucker reported the veterans would prefer to not move the memorial, and that they are willing to lose a lower planting ground if they can keep it in its current location, facing the 250 Bypass. Plans for both Alternatives C1 and G1 show a ramp running through there. The Project Team will also work on designing a gathering space for the Memorial, a feature that is currently not landscaped at the location.
Because of changes required by the Army Corps of Engineers to a proposed storm water retention pond, Mike Svetz of the City Parks and Recreation Department said the McIntire Park Master Plan would need to be changed to reflect multiple ponds spread along the Schenck’s Branch trail, rather than one big pond.
The main topic of conversation was a presentation of possible design alternatives for the bridge to carry the Route 250 Bypass across the interchange.
“The bridge is the focal point of this interchange, and depending on what style of bridge it can either drive us over our budget or keep us within budget,” Peery said.
In presenting a matrix of five options for Alternative C1 and four options for Alternative G1 (
), Peery said steering committee members would have to weigh the various trade-offs between the budget and aesthetics. He called the bridge selection process a “reality check,” saying that higher prices are what you get when “you go outside the box.”
Peery warned the steering committee that the ultimate bridge selection would not have the same impact as the stone bridge that carries motorists traveling to Monticello.
For Alternative C1, Option 1 would carry 2 spans over a 460 length feet across an impressive pair of concrete arches at a cost of $10.1 million, bringing the total project up to $38.1 million. That assumes a 25 percent contingency. Option 2 is cheaper, at $8.5 million for a 380 foot long concrete box girder bridge across three spans, with stone trim. The options decrease in price, with Option 5 built as a pair of precast concrete U-girder spans, at a cost of $3.5 million. While considerably But this option would lack many of the distinctive features that would make the project a “gateway” for Charlottesville.
Bridge cost estimates for Alternative G1 range from $3.9 million to $6.4 million. Steering committee members were asked to consider design elements independent of their use in any of the interchange alternatives.
Steering committee member Robert Winstead said that the bridge should be designed with the same character as existing bridges on the Route 250 Bypass. “We’re not designing this thing in a vacuum,” he said. He also said that the 25 percent contingency fee factored in to the provided estimated was too high.
Fellow steering committee member Lee Middleditch suggested there were too many options, and that a financial figure should be put out for the bridge first before thinking out the logistics.
Peery said that it was unclear how much money was going to be available from the federal government for construction, but suggested that parts of the project be phased. “There are options that we need to sharpen our pencil for sure but also want to work within your palette,” he said.
Committee members also asked RKK to keep bridge maintenance and long-term maintenance costs in mind when refining the bridge design alternatives.
At some point in the review process, the Board of Architectural Review will weigh in on the project. City Planner Mary Jo Scala said the BAR has never reviewed something as large as a bridge before.
At the City Council meeting,
Mayor David Brown
expressed safety concerns about roundabouts. RKK Traffic Engineer Jeff Parker previewed a presentation that might one day be made to City Council to allay fears about the safety of roundabouts. He pointed to a 1999 study from the Institute of Transportation Engineers which showed significant reductions in accidents in 7 out of 8 intersections converted from stop-signs to roundabouts, as well as a 2000 Insurance Institute for Highway Safety study which showed similar results.
Parker said no one is ever going at full speed as they travel through a roundabout, and that pedestrians only have to worry about one lane of traffic at a time.
VDOT even has a demonstration of roundabouts on their site
. Peery promised an education campaign if the roundabout is built.
No official decisions were made at this meeting. RKK will continue refining the design alternatives,
incorporating a general consensus among the staff to continue revising bridge options 2 and 3. RKK staff are also completing environmental evaluations, and plan to hold a National Environmental Policy Act (NEPA) public hearing in the fall.
Mayor Brown also requested to see a video drive-through of each of the renderings. Peery said his team was working on putting this together in advance of the next Steering Committee meeting, and was trying to craft the computer simulation so that it would be an accurate representation of travel through the roundabout.
The next steering committee meeting will be held sometime in late September.