1. According to Greek design guidelines, the highest design speed for freeways is 120 km/h, but can be 130 km/h in flat areas. 2. In practice, calculations showed operating speeds on certain highways exceeded design speeds, with passenger cars reaching 144 km/h on tangents and 128 km/h on sharp curves. 3. There are inconsistencies between theoretical design speeds and actual operating speeds on Greek highways, with some highways having much higher speeds than design guidelines suggest.

1. Very High Design Speeds
Case: GR
Basil Psarianos
Nat’l Techn. Univ. Athens, Greece
bpsarian@mail.ntua.gr

2. IN THEORY
(GR Design Guidelines 2001)
• Highest Design Speed can be:
– 120 km/h (75 mph) in general for
Freeways, but
• Can reach the value of
– 130 km/h (~80 mph) in flat topography
Transportation Research Board 2
2006 Annual Meeting

3. IN THEORY
HERE…
The Design Speed is 120 km/h and
The Speed Limit is 120 km/h (75 mph)
but
Transportation Research Board 3
2006 Annual Meeting

4. IN PRACTICE
WE MADE OUR ALCULATIONS
Transportation Research Board 4
2006 Annual Meeting

5. IN PRACTICE
AND THE RESULT WAS
Transportation Research Board 5
2006 Annual Meeting

6. IN PRACTICE, for Example
Design Speed = Operating Speed = 85% Speed (as of December 2005)
On the TANGENT:
• Passenger Cars: 144 km/h (90 mph) in the driving middle lane (3.50m)
• SU Trucks: 89 km/h (55.63 mph) in the driving middle lane
• Truck-Trailers: 87 km/h (54.38 mph) in the driving middle lane
• Buses: 98 km/h (61.25 mph)
Corinth-Athens Freeway, St.:57+550
Speed Limits (km/h):
120 for PCs, 80 for SU Trucks, 70 for Truck-Trailers, 90 for Buses
Transportation Research Board 6
2006 Annual Meeting

7. IN PRACTICE, for Example
Design Speed = Operating Speed = 85% Speed (as of December 2005)
On this SHARP HORIZONTAL CURVE with R=400 m (1311 ft):
Passenger Cars: 128 km/h (80 mph) in the driving right lane (3.50m)
Athens - Salonika Freeway, St. 98+000
Posted Speed : 90 km/h (56 mph)
Transportation Research Board 7
2006 Annual Meeting

8. Fast & General Conclusions
1. Inconsistencies between Theory
and Practice in various Design
Aspects
2. High Design Speed Highways are
OUT THERE; we in GR & EU do not
want to admit it and perhaps face
it!
Transportation Research Board 8
2006 Annual Meeting