Transcript Slide 1

A Handbook That
Outlines
• When traffic impact studies should be required
• What analyses should be included
• How the study should be reviewed and used
• Who is qualified to prepare and review impact
studies
Current Problems
• Communities do not adequately address
traffic implications of zoning and land use
decisions.
• A standard practice is needed.
• Site traffic impacts are often ignored,
misunderstood or inappropriately used.
• Mitigation measures are not addressed.
What Can Traffic Impact Studies Do?
• Forecast traffic impacts.
• Assist in evaluation of rezonings and
proposed land developments.
• Evaluate number/location of access points.
• Identify a basis to allocate costs of
improvements.
• Help promote a coordinated review.
Elements of Handbook
Why is a Traffic
Study Needed?
Review Process
and
Coordination
When is a
Study Needed
and What Type
is Required?
Impact
Analyses
Qualifications
of Preparer and
Reviewer
Mitigation
Analysis
Site Access and
Circulation
Review
Preliminary Considerations
• When traffic studies should be
required.
• Require different types of traffic
impact studies based on scale of
development.
• Pre-application conference to discuss
specific issues.
Types of Traffic Studies
• Rezonings: contrasting impacts of
representative uses for current v. requested
zoning.
• Traffic Impact Assessment: smaller projects,
analyze site access points.
• Traffic Impact Statement: traditional traffic
study, includes nearby signalized
intersections.
• Regional Traffic Analysis: comprehensive
study of a large area.
Trip Generation Sources
• Trip Generation, a nationally recognized
manual published by the Institute of
Transportation Engineers (ITE).
• Recent local data from at least three similar
uses.
When Should Traffic Impact Studies
be Required for Rezonings?
• Rezoning inconsistent with Master Plan if potential
uses could generate 100+ more peak hour directional
trips than uses under current zoning.
• Rezoning consistent with Master Plan but generate
1,000 daily trips or rezoning is considered premature
because of traffic conditions.
• Rezoning along designated “congested,” “critical” or
“safety management” corridors.
• Rezoning studies evaluate representative or worst
case uses, not just a particular use.
When Should Traffic Impact Studies Be
Required?
Projects Which…
Type of Study
Required….
Generate > or < 100 pk. hr. dir.
Trips or > 500 or < 750 trips daily
Impact Statement
Generate 100-500 pk. hr. dir.
trips or 750 + trips daily
Impact Statement
Are along identified corridors
Varies
Involve “significant” change or
expansion to PUD or use
Varies
Generate 500+ dir. pk. hr.
Other cases – Special Land Uses,
etc.
Regional Analysis
Varies
Peak Hours
Traffic impacts should be evaluated for a
typical week day:
• a.m. peak hour of adjacent streets
• p.m. peak hour of adjacent streets
• Saturday peak hour for certain commercial
uses
• daily traffic figures useful for planning
Examples of Trip Generation to
Meet Study Thresholds
Use
50 Peak
Hr. Dir.
100 Peak
Hr. Dir.
Single Family Units
70
150
Apartment units
115
245
Shopping Centers (sq.
ft.)
Fast Food Restaurant
(sq. ft.)
Office (sq. ft.)
5,200
15,500
2,600
5,200
22,000
55,000
Light Industrial (sq. ft.)
58,000
115,000
Rezoning Traffic Study- Compare Uses
Current Office
Zoning
– Municipal Offices
– General Offices
– Medical Offices
– Funeral Homes
Proposed Commercial
Zoning
– Offices
– General Retail
– Gas Stations
– Restaurants
– Motels
– Shopping Centers
Preapplication Conference
• Who to involve….
• Items to discuss
 type of study needed
 study area
 availability of data
 background traffic growth
 other nearby projects to include
 programmed roadway improvements
 trip generation sources/trip reduction factors
 horizon year
 other issues
Traffic Impact Study Should Include
1. Recent traffic counts, especially peak
hour(s)
2. Existing levels of service analysis
3. Background traffic growth
4. Trip generation of project
5. Trip distribution rationale
Traffic Impact Study Should Include
6. Future levels of service
7. Crash (accident) history, if appropriate
8. Site access and internal site circulation
review
9. Mitigation alternatives and
recommendations
Levels of Service (LoS) Analysis
• LoS mathematically measures traffic
operations.
• Based on vehicle delays for various movements.
• Best measured for peak hours.
• Scale A-F
A/B = no or little delay
C/D = some delays, typical design standard
E = volumes near or at capacity, congestion
F = significant congestion/delays
Examples LoS Summary
Signalized Intersection
Approach
A.M. Peak Hour
P.M. Peak Hour
Delay (sec.)
LoS
Delay (sec.)
LoS
Eastbound
34.1
D
46.9
E
Westbound
26.7
D
41.1
A
Northbound
18.2
C
17.7
C
Southbound
124.1
F
20.9
C
Overall
52.9
E
32.1
D
Evaluation of Mitigation
Alternatives
• Roadway improvements – bypass lane,
deceleration lane, widening, construct new
street, etc.
• Access management techniques – service
drives, deceleration lanes, prohibit certain
turns, median, etc.
• Operational improvements – install traffic
signal(s) or change timing, demand
management techniques, uses of public
transit, etc.
• Responsibility, timing and funding.
Implementation
• Master planning and corridor
planning
• Adopt or amend ordinances
• Staff training
• Agency coordination
Revise Ordinances
• Incorporate model ordinance as a General
Provision
• Reference in the site plan review section
• List uses meeting the thresholds as special
land uses
• Encourage mixed use developments and
connections between developments
• Adopt access management standards
• Require submittal of a study for certain
rezonings through “Ordinance Amendment”
regulations
Qualifications
• 3+ years recent experience preparing traffic impact
studies
• Impact studies comprise a major component of
preparer’s work
• Familiarity with the Highway Capacity Manual
• Education or training in traffic impact analyses
• Member of ITE or TRB
• Registered PE/AICP/PCP or professional
transportation planner
Any signal or design work should be prepared by a PE
trained in traffic engineering.
Summary of Michigan Cases and
Constitutional Issues:
• Subdivision Control Act, Mobile Home Act
and Zoning Enabling acts do not authorize
requiring a developer to fund off-site
improvements.
• Constitutionality of off-site improvements
has been upheld under the driveway permit
approval process.
Traffic Study Review:
Training/Coordination
• Training staff and/or use consultants.
• Obtain reference materials.
• Establish a review system between the
community and local road agency and/or
MDOT.
• Coordinate with MPO, 3-C, Public Transit or
Regional Planning Agencies.
Other Important Tools to Manage
Traffic:
• State/MPO long range
plans
• Right-of-way
preservation
• Master plans
• Zoning/subdivision
regulations
• Corridor plans
• Thoroughfare plans
• Access management
• Mixed use
developments
• Public Transit
• Transportation
demand management