Street Redesign Toolkit

Street Redesign Toolkit

Analyze existing street configurations and propose lane reallocation to improve walkability and safety while maintaining traffic flow. Apply Jeff Speck's Asphalt Audit methodology to identify "extra" asphalt and rededicate it to pedestrians, bikes, and parking.

Constitutional Constraints

• Evidence-based dimensions - All lane widths, parking dimensions, and bike facility widths must follow NACTO Urban Street Design Guide standards
• Capacity analysis required - Do not remove lanes without reference to traffic counts or capacity analysis
• Safety as primary justification - Lead with safety improvements (crash reduction); economic and livability benefits follow
• Cost-consciousness - Distinguish between paint-only solutions (near-zero cost) and reconstruction (significant cost)
• Context sensitivity - Recommendations must match the street's context (downtown vs. arterial vs. residential)

When to Use

• Redesigning an over-engineered street with excess lanes
• Implementing a road diet (4-to-3 or similar lane reduction)
• Adding bike facilities to existing streets
• Improving pedestrian crossings and safety
• Complete streets projects
• Downtown street revitalization
• Recovering space from oversized lanes

Don't Use When

• Initial diagnosis needed (use walkability-audit first)
• Opposing a road expansion (use induced-demand-analysis)
• Focusing specifically on parking policy (use parking-reform-framework)
• Rural highway or non-urban context

Inputs

NACTO Standard Reference

Lane Widths

Key Insight on Lane Width

Speck's formulation: "Traffic engineers designed our urban streets using highway standards. A 12-foot lane makes sense at 70 mph. At 30 mph, it's an invitation to speed."

Research finding: Studies show crashes are lowest with lane widths between 10 and 10.5 feet. Every additional foot above 10 feet increases speeds and crashes.

Street Redesign Workflow

Step 1: Document Existing Conditions

Create a cross-section inventory:

Step 2: Analyze Capacity Needs

ADT-to-Lanes Rule of Thumb:

Critical insight: The classic 4-to-3 road diet (four lanes to three: one travel each direction + center turn lane) typically works for ADT up to 20,000-25,000 with no capacity reduction, because the turn lane eliminates left-turn delays.

Step 3: Identify Recoverable Space

The Asphalt Audit Method:

1. Eliminate excess lanes - If traffic counts show 2 lanes can handle the volume, remove extras
2. Narrow remaining lanes to 10 feet - Recover 2 feet per lane narrowed from 12' to 10'
3. Calculate total recoverable space - Sum of eliminated lanes + narrowing gains

Step 4: Reallocate Recovered Space

Priority Order for Reallocation:

Example Reallocation (60' curb-to-curb):

Before:

• 4 x 12' travel lanes = 48'
• 2 x 6' bike lanes = 12'
• Total = 60'

After (road diet to 3 lanes):

• 2 x 10' travel lanes = 20'
• 1 x 10' turn lane = 10'
• 2 x 6' protected bike lanes with 2' buffer = 16'
• 2 x 7' parking lanes = 14'
• Total = 60'

Step 5: Design Key Intersections

Crossing Improvements:

Step 6: Document Before/After

Cross-Section Comparison:

BEFORE: [Street Name] - 60' Curb-to-Curb
|  6'  |  12' |  12' |  12' |  12' |  6'  |
| Bike | Lane | Lane | Lane | Lane | Bike |

AFTER: [Street Name] - 60' Curb-to-Curb
|  7'  | 2'|  6' | 10' | 10' | 10' |  6' |2'|  7'  |
| Park |Buf|Bike |Lane |Turn |Lane |Bike|Buf|Park |

Step 7: Calculate Safety Benefits

Road Diet Safety Research:

Step 8: Categorize Cost

Speck's insight: "You can restripe a whole downtown for the cost of rebuilding a few streets." Start with paint.

Output Format

## Street Redesign: [Street Name]

### Existing Conditions

**Configuration:**
- Total curb-to-curb: [X] feet
- Travel lanes: [X] x [X]' = [X]'
- Turn lanes: [X] x [X]' = [X]'
- Parking: [X] x [X]' = [X]'
- Bike facilities: [X]
- Sidewalks: [X]' each side

**Traffic Volume:** [X] ADT

**Current Issues:**
- [Issue 1: e.g., 12' lanes encourage speeding]
- [Issue 2: e.g., 4-lane crossing is dangerous]
- [Issue 3: e.g., no bike facilities]

---

### Capacity Analysis

| Metric | Value | Implication |
|--------|-------|-------------|
| Current ADT | [X] | [Lanes needed based on ADT] |
| Current lanes | [X] | [Excess lanes identified] |
| Capacity assessment | [Analysis] | [Can reduce to X lanes] |

---

### Recoverable Space

| Source | Width Gained |
|--------|-------------|
| Remove [X] lane(s) | [X]' |
| Narrow lanes 12'->10' | [X] lanes x 2' = [X]' |
| **Total Recoverable** | **[X]'** |

---

### Proposed Configuration

**New Cross-Section:**

| Element | Width | Notes |
|---------|-------|-------|
| Travel lanes | [X] x 10' = [X]' | NACTO standard |
| Turn lane | 10' | If applicable |
| Bike lanes | [X] x 6' = [X]' | [Protected/buffered/standard] |
| Parking | [X] x [X]' = [X]' | [Parallel/angled] |
| Buffer/planting | [X]' | If applicable |
| **Total** | **[X]'** | Matches existing curb-to-curb |

**Visual Cross-Section:**

[ASCII representation of proposed configuration]

---

### Intersection Improvements

| Location | Improvement | Benefit |
|----------|-------------|---------|
| [Intersection 1] | [Curb extensions, crosswalk] | [Reduced crossing distance] |
| [Intersection 2] | [Pedestrian refuge] | [Staged crossing possible] |

---

### Safety Benefits

| Metric | Expected Improvement | Evidence |
|--------|---------------------|----------|
| Overall crashes | -[X]% | FHWA road diet studies |
| Pedestrian crashes | -[X]% | Reduced crossing distance |
| Speeds | -[X] mph | Narrower lanes |

---

### Cost Estimate

| Phase | Elements | Cost Range |
|-------|----------|------------|
| Phase 1 (Paint) | Restripe lanes, bike lanes | $[X] |
| Phase 2 (Tactical) | Flexible posts, planters | $[X] |
| Phase 3 (Permanent) | Curb extensions, signals | $[X] |

**Recommended approach:** Start with Phase 1 (paint) to test configuration; make permanent after success demonstrated.

---

### Implementation Strategy

1. **Immediate (0-6 months):** [Restriping during scheduled maintenance]
2. **Short-term (6-18 months):** [Tactical improvements, signal changes]
3. **Long-term (2+ years):** [Permanent infrastructure if warranted]

---

### Comparable Projects

| City | Before | After | Result |
|------|--------|-------|--------|
| [City 1] | [Config] | [Config] | [X]% crash reduction |
| [City 2] | [Config] | [Config] | [Outcome] |

Example Summary

Input: "Our main street is 60 feet wide with four 12-foot lanes. Traffic is about 12,000 ADT. People complain about speeding and it feels unsafe to cross. We want to add bike lanes."

Output summary:

• Existing: 4 x 12' lanes = 48' + 2 x 6' unusable shoulders = 60'
• Capacity analysis: 12,000 ADT easily handled by 2 lanes + turn lane
• Recoverable space: 1 eliminated lane (12') + narrowing 3 lanes (6') = 18'

Proposed configuration:

• 2 x 10' travel lanes = 20'
• 1 x 10' center turn lane = 10'
• 2 x 6' protected bike lanes with 2' buffer = 16'
• 2 x 7' parking lanes = 14'
• Total = 60' (no curb changes needed)

Expected benefits:

• 19-47% crash reduction (FHWA road diet studies)
• Speeds reduced 5-10 mph (narrower lanes)
• Protected bike facilities added
• On-street parking added (buffers pedestrians, supports businesses)

Cost: Paint/restripe = ~$30K; can be done during scheduled maintenance for near-zero additional cost (Cedar Rapids approach).

Error Handling

Integration

This skill is part of the Jeff Speck expert persona. It operationalizes the Asphalt Audit methodology for specific street redesigns.

The skill embodies Speck's core insight: Unnecessary street width accomplishes nothing but inducing dangerous speeding. Recover it for people.

Pairs with:

• walkability-audit - Use audit to diagnose, then street-redesign to prescribe
• induced-demand-analysis - When redesign proposals face "traffic will get worse" objections

Success Criteria

A successful street redesign:

• Maintains or improves traffic capacity (no induced congestion)
• Reduces lane widths to NACTO 10-foot standard
• Adds or improves bike facilities
• Shortens pedestrian crossing distances
• Projects 19-47% crash reduction based on road diet research
• Identifies quick wins (paint-only options)
• References comparable successful projects