Miami’s Baywalk is unfinished after 40 years. New rules are aimed at getting the job done.

More than 40 years after its approval, the Miami Baywalk remains an unfinished dream — a hodge-podge of disconnected pathways that range widely in quality, access and appeal.

But two new measures approved by Miami commissioners on Thursday may hasten completion of the plan for a continuous public promenade radiating out from the Miami River along Biscayne Bay. The measures should also significantly boost the design quality, safety and sustainability of the Baywalk and the companion Miami Riverwalk as new segments are gradually installed.

One item, approved unanimously by commissioners, for the first time enacts comprehensive design guidelines for the walkways. The new rules, added to the city’s Miami 21 zoning code, will now prescribe high-quality paving materials, markedly improved lighting and directional signs and a specific palette of trees and plantings, while setting out a half-dozen detailed options for promenade layout. The guidelines also allow for environmentally friendly, sea-level rise resistant features, such as bioswales or living shorelines along Baywalk segments.

Separately, commissioners also approved a $4.3 million contract with Chicago-based engineering firm Exp U.S. Services to develop preliminary designs for a key missing link in the Baywalk — the piece under the Interstate 395 overpass connecting to the MacArthur Causeway. The design cost, which includes underwater surveys of bay bottom, is high because of the site’s environmental sensitivity and its proximity to the abutting Perez Art Museum Miami, city officials said.

Rough estimates of the cost of that connection range from $6 million for a basic bridge to as much as $20 million for an “iconic” destination bridge where people could gather, they said. Completion of that link would connect two long existing segments, effectively providing for a continuous promenade from the mouth of the river to the Edgewater neighborhood.

Under rules in force since the approval of the Baywalk plan in 1979, developers are obligated to set back new buildings a minimum of 50 feet from the water’s edge and build and maintain a 25-foot-wide promenade for public use wherever there is space to do so. But the old rules had only minimal design standards. As a result, the existing waterfront walkways consist of mismatched segments that range in look and functionality from the thoughtfully designed to the unappealingly bare. The new rules also apply to publicly owned segments in parks.

The guidelines, drawn up by the Miami firm of Savino Miller Landscape Architects and city planners, also provide design ideas for portions of the bay and river walks under bridges and overpasses, today largely dark and barren spots that often attract homeless encampments.

The new standards, backers say, will provide a unified look and better flow, eye appeal and clear connections to surrounding neighborhoods and streets. After dark, security will improve through mandated overhead lighting fixtures.

In addition, the rules now will require owners and developers making significant improvements to existing buildings to also install public promenades at the water’s edge, or a public greenway on the street if there is insufficient space behind the structure. Backers say that will accelerate the pace of construction as older buildings not previously subject to the requirement are renovated, expanded or converted to new uses, such as the booming number of restaurants on the river.

“This will cement the Miami Baywalk as a community asset for generations to come,” said Miami commissioner Manolo Reyes, also chairman of the Downtown Development Authority, which pushed for the improved Baywalk rules. “This has been 40 years in the making. We are trying to make it cohesive so it can be something we can all be proud of.”

The new rules, which exempt areas zoned for single-family homes and duplexes or small apartment buildings, could produce a unified, continuous Baywalk from northern Coconut Grove to the Edgewater neigborhood and the Tuttle Causeway, though they also apply to any waterfront high-density areas between that last point and the city’s north boundary at Northeast 87th street. Most of the city’s Upper East Side consists of single-family neighborhoods.