Growth Management Advisory Committee
Overheads Presented at January 16, 1998 Meeting

• Prevent congestion
• Scale compatibility, avoid overshadowing
• Minimize disruptive district transitions
• Prevent worsening of flood risk
• Encourage inclusion of affordable housing
• Protect open space

• Adoption would reduce traffic volumes near development.
• Impact Citywide depends upon:
  • where "displaced" jobs & housing actually locate.
  • how much "outside" traffic would be attracted;
  • how much lower densities would lower transit share.
• Adoption would probably result in:
  • fewer building "tear-downs;"
  • more nonconforming buildings (unless special provisions avoid that);
  • uncertain impact on housing affordability;
  • uncertain impact on job types

Evaluative Observations:

• There are many powerful causes of traffic increases in Cambridge besides development in Cambridge.
  • 14.5% per year auto registration increase in Cambridge;
  • 0.3% per year increase in households;
  • 1.0% per year increase in jobs;
  • 2.0% per year increase in regional traffic potential;
  • Life style changes.
• Simple FAR reduction reduces trips only by reducing future jobs, housing, and taxable floor area.
• Bulk control inexactly addresses traffic: trips vary hugely in relation to floor area among business uses & locations.
• Performance-based zoning controls could more sensitively address congestion and less heavily impact jobs, housing and taxes.

Purpose: scale compatibility, avoid overshadowing

Prior Proposals:

• Reduce FARs
• Reduce heights
• Establish uniform cornice line.

Impact Observations:

• Height reduction consequences vary in complex ways by district.
• Appropriate heights may vary within present districts.

Purpose: prevent worsening of flood risks

Prior Proposals:

• Apply 100-year flood zone rules to 500-year flood zone
• Reduce flood zone FAR to 0.5.

Impact Observations:

• Proposals might result in lower larger footprint buildings.
• Proposals substantially reduce Alewife area building potential.

Evaluative observations:

• Alewife flooding is a real but complex problem, and these proposals don't address real causes.
• FAR only indirectly relates to flood displacement or groundwater recharge.
• 500-year flood zone controls provide small risk reduction at large "cost."
• 500-year flood zone poorly describes the relevant drainage area.
• More effective techniques are available.

2. Establish District Transition Rules

Purpose: minimize disruptive district transitions

Prior Proposal: establish Transition Control Plane

Impact Observations:

• The proposal is highly complex in application.
• Creates large disparities between height and FAR as allowed and that which is feasible.

Evaluative Observations:

• Appropriateness varies among district boundary conditions.
• Likely to increase variance requests.

3. Protect Open Space

Purpose: avoid excessive impervious surfaces, loss of open space

Prior proposal:

• Revise on-lot open space dimensional rules.
• Reconsider Open Space District FAR rules.

Impact Observations:

• On-lot dimensional rules address concerns directly.
• Dimensional rules significantly reduce achievable FAR on some parcels.
• Proposed Open Space District rules may constrain recreational facilities.

Evaluative Observations:

• Housing cost increases resulting from open space rules on small parcels might hurt housing affordability.
• Dimensional proposal is likely to increase demands for relief by variance and for staff interpretation of complex rules.

4. Affordable Housing Inclusion

Purpose: encourage inclusion of affordable units in housing developments

Prior proposals:

• [Petition] Provide 25% density bonus as incentive if half "extra" units are affordable.
• [Department] Require developments over some size to include affordable units, compensated by density increase.

Topics and Items

Topic 1. Reduce FAR, Height & density

• Reduce FAR in Residence A, B, and C-1 zones.
• Reduce FAR in Commercial zones.

Topic 2. Establish district transition rules

• Transition and height rules.

Topic 3. Protect Open Space

• Revise Residential open space rules.
• Reconsider Open Space District FAR rules.

Topic 4. Affordable Housing Inclusion

• Inclusionary zoning