The construction of bus-only lanes in Arlington’s Crystal City community is inching along, and the estimated opening date is spring 2016 — a year out from earlier projections.

Arlington officials say major work is almost completed in the county’s 2.25-mile portion of the Crystal City Potomac Yard Transitway, a five-mile route connecting the Crystal City and Braddock Road Metro stations. The new transitway is the region’s introduction to bus rapid transit, a system that uses dedicated bus lanes to more quickly and efficiently move masses of people along a corridor. Alexandria’s portion opened in August 2014.

In coming weeks, crews will be installing shelters, roof decks and real-time information displays at seven stations planned in the Arlington side, county officials announced this month. They will also work on pavement markings and sign installation.

“We are making progress, and we are getting to where the end is in sight,” Deputy County Manager Carol Mitten told the Arlington County Board at its Dec. 15 meeting.

Setbacks during the construction, including bad weather and longer waits for permits, pushed back the opening about a year. Officials said crew found poor soil conditions, unmarked utilities, and obstructions that that led to delays, and the county was forced to redesign the station roofs after it couldn’t find a supplier for the size and type of roof panel needed in the transitway station design. To stay on budget, the county made other changes to the project including purchasing prefabricated bus shelters.

“Unfortunately we encountered one too many things that we just couldn’t absorb into the contingency and we couldn’t absorb into the schedule,” Mitten said. “We do regret the delays that we have had…and we expect to deliver this in the spring.”

When the project is completed, Arlington will have just under a mile of transit-only roadway and 1.5 miles of on-street dedicated transit lanes that will be effective during the morning and evening rush hours. That means in a stretch on Crystal Drive and Clark Street, north of 26th Street, buses will have exclusive use of a lane from 6 a.m. to 9 a.m. and from 3:30 p.m. to 7 p.m. The stretch of bus roadway will run from the Alexandria line to 26th Street. This county map shows the route alignment:

Arlington is working on an enforcement mechanism in case other vehicles try to take over the new lanes and is planning to establish $200 fines for drivers who use the bus lanes.

Officials view the project as critical to enhancing transit options in the growing Route 1 corridor and supporting redevelopment and development efforts in the area. They expect many of the riders will come from Alexandria’s growing Potomac Yard area, which has seen significant housing growth in recent years and is anticipated to see continued residential and commercial growth.

The Alexandria stretch that opened in August 2014 includes just under a mile of busway built between the northbound and southbound lanes of U.S. Route 1, also known as Jefferson Davis Highway, in Potomac Yard. When that first phase of the project opened, Metro launched Metroway, featuring new buses and frequent service in the dedicated travel lanes.

So far officials say they are encouraged by the use of the service. Daily ridership was about 1,660 in October, up by about 300 since the Metroway service launched a year ago. Transit officials project 3,570 daily riders by 2017. Many will be taking a connection from Metrorail into the growing community at Potomac Yard or commuting to work along the corridor. Some are expected to be residents getting around in the corridor, where there are large employment sites, restaurants, and entertainment and shopping sites.

“We expect ridership to continue growing once the Transitway is fully completed,” Arlington County spokesman Eric Balliet said.

Besides offering frequent service and stations equipped with real time arrival information and high platforms that allow level boarding, transit officials are planning other features for the corridor, including an off-board payment system and ways to allow passengers to board using all bus doors. An off-board payment option has the potential to improve the flow of passengers on and off buses and speed bus travel. It’s unclear, however, when those features will be implemented.

Some bus routes with Arlington’s transit system, ART, will also benefit from the bus lanes. Those include the ART 43 and ART 92, serving Crystal City.

Transit advocates, including Metro, have said the Crystal City Potomac Yard Transitway should be an example of improved bus service across the Washington region where buses are often stuck in traffic, constantly late and traveling at speeds under 10 mph. Metro has been advocating for more investments in bus lanes, including one in the District’s busy 16th Street NW corridor.