Greater Washington is destined to become a polycentric metropolis in which downtown Washington will be one of many “downtowns” within the region. But will polycentric greater Washington be great? Without more regional thinking, coupled with coordinated public actions and infrastructure investment, probably not.

Explore greater Washington — Prince George’s, Montgomery, Arlington and Fairfax counties and Alexandria. You will see numerous formerly suburban areas that are becoming denser and more urban, and ultimately more urbane. However, making this future polycentric metropolitan region really great will depend above all on developing an effective, region-wide system of transportation tying these areas together.

It also will depend on more affordable housing opportunities across the region for an expanding, increasingly mobile workforce; more business and institutional employment opportunities throughout the region; greatly improved elementary and secondary education in all the region’s jurisdictions; and improvements in preserving and sustaining the region’s environmental assets.

Achieving all this is challenging in a region so jurisdictionally fragmented and governed: two politically disparate states encompassing multiple counties and municipalities surrounding the national capital, a federal district that is a hybrid between being a state and a city. Yet the region’s evolution as a polycentric metropolis is partly attributable to this fragmented political structure. Each jurisdiction can shape its geographic domain as it sees fit, largely independent of what nearby jurisdictions are doing.

Despite differences, regional jurisdictions are pursuing urban transformation for many of the same reasons: to help alleviate local transportation, housing, employment, education and environmental problems. Thus, even while acting independently, they may be contributing to solving regional problems.

Still, the question remains: Will the whole — the metropolitan region — be greater than the sum of its parts? Urbanizing Wheaton, New Carrollton or Tysons Corner may enhance local conditions, but will the quality and functionality of the entire region benefit?

Creating a multi-modal, metropolitan transportation system is by far the most indispensable, concerted action needed to make the region function well. This system must directly interconnect existing and planned urban nodes, the region’s future constellation of evolving downtowns.

Located at or near Metrorail stations, urban nodes exemplify transit-oriented development (TOD), a fundamental “smart growth” policy and planning goal shared by most planners. Yet virtually every Metrorail station is on a line in a network planned half a century ago. The Metro network’s hub-and-spoke pattern, based on the region’s 1960s “wedges and corridors” plan, anticipated predominantly radial movement into and out of the hub, downtown Washington. A polycentric, regional metropolis was never envisioned.

With polycentric metropolitan Washington a certainty, we will need a lattice-like transportation network enabling circumferential as well as radial movement. The light rail Purple Line traversing Montgomery and Prince George’s counties will be a first step toward creating such a network. The recently opened Intercounty Connector, facilitating circumferential car and truck movement between these two Maryland counties, is likewise a first step in building a more complete, interconnected vehicular network.

Thus, the region’s future transportation network must become in effect a polar grid pattern allowing more direct travel from Wheaton to Tysons Corner or New Carollton, or from Eisenhower Avenue to Reston. For transit riders, this would save time and eliminate going in and out of downtown D.C. Moreover, future transit lines do not have to be Metrorail lines. They can be streetcar lines, Bus Rapid Transit (BRT) lines or a transportation technology yet to be developed. A complete and effective regional network also would require new bridges or tunnels crossing the Potomac River.

One other obstacle must be overcome. The Washington Area Metropolitan Transit Authority (WMATA), although presumably acting regionally, is controlled and funded by the disparate jurisdictions it serves. Inevitably local political and economic interests greatly constrain WMATA’s ability to adopt policies and then finance and implement region-wide transit plans. To adequately serve a polycentric metropolis, WMATA must have more planning and financial autonomy.

Given the substantial lead time and capital investment necessary to create new transportation corridors and rights-of-way, it’s not too soon to start long-range planning for the metropolitan network of the future. Indeed, it’s already a bit late.

Roger K. Lewis is a practicing architect and a professor emeritus of architecture at the University of Maryland.