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Procedure for Setting Speed Limits based on Findings in Greece
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GREEK GUIDELINES FOR SETTING SPEED LIMITS
B. Psarianos, S. Palaskas, Nat’l Techn. Univ. Athens, Greece N. Stamatiadis, Univ. of Kentucky, U.S.A.
SPEED LIMIT?
Speed Limit: It’s a Problem
Transportation Research Board 2006 Annual Meeting
3
See this Example Design Speed = Operating Speed = 85% Speed (as of December 2005)
On the TANGENT:
• Passenger Cars: 144 km/h in the driving middle lane (3.50m) –VIOLATION 24 km/h
• SU Trucks: 89 km/h in the driving middle lane
• Truck-Trailers: 87 km/h in the driving middle lane
• Buses: 98 km/h
Corinth-Athens Freeway, St.:57+550
Speed Limits (km/h):
120 for PCs, 80 for SU Trucks, 70 for Truck-Trailers, 90 for Buses
General Speed Limits: The easy part
Vehicle Type FREEWAYS High speed roads Other rural roads
Passenger cars 130 110 90
Buses 100 90 80
Articulated Buses 70 70 70
School Buses 80 80 60
Trucks ≤ 3500 kgr 100 90 80
Trucks > 3500 kgr 85 80 80
Semi Trailer Truck≤ 3500 kgr 80 80 70
Semi Trailer Truck> 3500 kgr 80 70 70
Motorcyclists ≥ 125 cc 130 110 90
Motorcyclists < 125 cc 80 80 70
Vehicle Type FREEWAYS
Freeways – wet pavement 110
High speed roads – wet pavement 90
Other road network – wet pavement 80
Freeways / High speed roads - Bridges 100
Freeways / High speed roads - Tunnels 100
Local Speed Limits The difficult part
King of the Road
It’s always the Driver!
By The Book
• Driver selects his/her safe speed accordingly • Speed Limit is set only when driver can not perceive the
safe speed (obscured road, sudden pedestrian traffic, pavement deterioration etc.)
• Speed Limit the last measure for road engineering • CONDITIONAL and EXCUSED Speed Limit
Who Decides?
• Engineering Study • Technical Team consisted by
– The Road Director, – Local Police, – Technical Chamber of Greece
• Primary Reference: OPERATING SPEED (V85) • Use of Advisory Speed especially on Ramps for Heavy
Traffic • Every 10 years regular reconsideration if not enforced by
accident history of specific site
Parameters? • Grade (Speed Differential / Variance) • Sharp curvature • Sight Distance • At-Grade Intersection (generally 70 km/h) • Presence of Vulnerable road users (Children, Elderly People,
Bicyclists) • Accident History • Weaving Areas • Roadside Development • Specific Sites (Schools, Stadium, Animal Passage, etc)
For Example: Roadside Development
MAXIMUM SPEED LIMIT (KM/H)
Distance between Accesses (m)
Rural & suburban
roads
Urban roads
(Through roads)
70 350 - 60 300 - 50 ≤250 ≤250 ≤50 ≤200 ≤200
For Example: Through Traffic at Freeways
Roadway Functional Classification CROSS
SECTION TYPE
Speed Limit (km/h)
Rural Freeways /High Speed Highways divided undivided
130 120 110 100 90
Rural Roads between regions /counties divided 110 100 Rural Roads between cities/towns divided 100 90
Urban Freeway / Urban divided 90 80
For Example: Weaving Sections at Interchanges
Weaving Type Weaving Length [m] Area Comments
Speed Limit
[km/h] `
200
Rural &
Urban Cloverleaf interchange
type 100
180 80
250 Rural &
Urban between two interchanges
100 200 80 180 Urban 60
For Example: Interchange Ramps with max Cross-Slope 6%
Inner Curve
Radius (m) 35 35 115 170 250 (340)
Speed Limit (km/
h) 30 40 50 60 70 (80)
More Advisory Speeds
• Advice drivers on probable dangerous conditions when exceeding the advisory speed limit like
• Intersections with restricted visibility • Narrow Bridges or One-Lane Bridges • Downgrades greater than 6% • Ramps especially for Heavy Vehicles • On Crest and Sag Vertical Curves
• It can be the operating speed or safe speed • Accompanied with explaining sign
Conclusions
• A modern guide to help agencies set reliable speed limits that will be obeyed • Less necessity for enforcement • Better acceptance by the driving population