1000 Hydraulics Chapter - Ministry of Transportation

BC MoT
SUPPLEMENT TO TAC GEOMETRIC DESIGN GUIDE
MoT Section 1040 TAC Section Not Applicable
Check For Outlet Control
Headloss (H) for full flow conditions can be estimated
using the following figures:
For circular CSP and SPCSP:
• CSPI Handbook of Steel Drainage and Highway
Construction Products (2002), Figure 4-17, 4-18, p.
158, p. 159.
For CSP and SPCSP pipe arch:
• CSPI Handbook of Steel Drainage and Highway
Construction Products (2002), Figure4-19, 4-20, p.
160, p. 161.
For circular concrete pipe:
• RTAC Drainage Manual Volume 2 (1987), Figure
4.7.14, p. 4.48.
For concrete box culvert:
• RTAC Drainage Manual Volume 2 (1987), Figure
4.7.13, p. 4.47.
Headloss (H) for partially full flow conditions can be
approximated using the equation from the CSPI
Handbook of Steel Drainage and Highway Construction
Products (2002), p. 146, or equation 4.5.4 from the RTAC
Drainage Manual Volume 2 (1987), p. 4.18.
The headwater depth under outlet control (HW out ) can be
estimated using CSPI Handbook of Steel Drainage and
Highway Construction Products (2002), p. 143, or
equation 4.5.10 from the RTAC Drainage Manual
Volume 2 (1987), p. 4.20.
For information on outlet control, refer to:
♦ RTAC Drainage Manual Volume 2 (1987), p. 4.18.
♦ CSPI Handbook of Steel Drainage and Highway
Construction Products (2002), p. 143.
Hydraulic Programs
Hydraulic computer programs have distinct advantages
over hand calculations or nomographs for determining
normal depth, culvert velocity, hydraulic radius and area
of flow for partially full flow conditions.
• CSPI Handbook of Steel Drainage and Highway
Construction Products (2002), p. 150.
Critical Flow
For information on critical flow, refer to Section 1030.03.
Treatment of Inlet/Outlet Structures
Riprap, in combination with geotextile, is generally used
for inlet and outlet protection. The average culvert
velocity during the design flow should be used to
determine riprap requirements. For information on riprap
lining and filter blanket, refer to Section 1030.04.
To prevent scour around the inlet and outlet, riprap shall
be placed in the channel bed and side slopes. The length
of the inlet apron should be at least equal to twice the
culvert rise while the length of the outlet apron should be
at least equal to four times the culvert rise. The riprap
should be placed to a height of at least 0.3 m above the
high water level (HWL) or above the crown of the pipe,
whichever is higher.
For information and details on concrete inlet and outlet
structures, refer to:
♦ Specification Dwg. No. SP303-01 to 04, MoT
Standard Specifications for Highway Construction.
♦ RTAC Drainage Manual Volume 2 (1987), p. 4.25
and 4.103.
♦ CSPI Handbook of Steel Drainage and Highway
Construction Products (2002), p.300.
Page 1040-4 June, 2007