Cambridge streets will be increasingly clogged with traffic and its public transit system overwhelmed, if massive citywide development goes forward as now envisioned.

New projects will bring at least 50,000 additional car trips per day and 50,000 additional transit trips per day. (Kendall Square development alone will add 30,000 of each, according to city consultants McMahon & Associates.)

Many Cambridge intersections are already heavily congested and the Red Line is packed at rush hour. Yet development scenarios include no expansion of street and subway carrying capacity.

City traffic planners say our streets will be able to handle this huge influx of vehicles: they focus primarily on “puffball” intersections which never congest, while ignoring existing bottlenecks.

Traffic reduction measures—encouraging commuters to walk, bike, carpool, or take the subway—are to be commended, but the city expects the steep increase in car trips evenwith those measures.

The MBTA is facing a $130 million deficit in its operating budget next year. While the city has suggested improvements to the Red Line, there is no plan or funding in sight.

The Cambridge Residents Alliance is calling on the City Council to reject any major zoning changes to allow massive density and height increases, until the city’s consultants have produced a thorough, written traffic and transit report that describes how the city’s transportation infrastructure would handle all the new development.

Stephen Kaiser, Ph.D., who served as a traffic engineer for 15 years with two stateagencies, has produced a detailed traffic report for the Cambridge Residents Alliance that analyzes the problems described above.