Ten drivers participate in
driving simulation tests to examine the horizontal and vertical design indices
of the basic sections of freeway underground interchange ramps. Using UC-win/Road, simulation models are established under various working
conditions to collect driving characteristics and cardiac physiological data
across eight different scenarios. The heart rate growth rate is used as a
driving load and is calibrated with real-world driving
data. Through regression analysis, a theoretical model is developed to link
horizontal and vertical geometric design indices, driving speed, and driving
load for combined sections involving longitudinal slopes, horizontal curves,
and bends. Recommended indices for circular curve radii are derived based on
the maximum superelevation rate. Key findings from the tests include: (1) The
average driving speed on the left curve is 5.6% higher than that on the right
curve, and the average heart rate growth rate increases by 9.0%. The average
driving speed on the downhill section is 3.2% higher than that on the uphill
section, and the average heart rate growth rate increases by 6.8%. (2) The
driving load on the left curve section is higher than that on the right curve
section, and the driving load on the downhill section is higher than that of
the uphill section. (3) At a design speed of 40 km/h, the safe gradients of the
downhill and uphill sections are 4.56% and 5.35%, respectively, based on driving load. (4) The recommended
indices for the circular curve radius of the underground interchange range from
1.17 to 2 times that of the surface interchange, and this difference gradually
increases with increasing longitudinal slope and design speed.
WANG Zuo
,
ZHANG Chi
,
JIAO Yuqi
,
LIN Xuancai
,
YAN Jiaqiang
. Geometric Design Indices of
Freeway Underground Interchange Ramps
Based on Driving Load[J]. Tunnel Construction, 2025
, 45(2)
: 256
-267
.
DOI: 10.3973/j.issn.2096-4498.2025.02.002
