A method for estimating traffic operation efficiency and time economic loss in flooded road sections

Abstract

The present invention discloses a method for estimating traffic operation efficiency and time-based economic losses on flooded road sections. The method comprises: establishing a model for the relationship between flood depth and distance; calculating the free-flow speed and average speed before and after the flooding based on the flood depth at each point on the road section; calculating the travel time before and after the flooding to obtain the delay time caused by the flooding on the road section; and estimating the total time-based economic losses per unit time on the flooded road section based on the average delay time of each type of vehicle, traffic flow, number of passengers, and unit time value. The present invention can numerically calculate the travel speed, travel time, and delay time on flooded road sections, providing technical support for evaluating the impact of flooding on road traffic operation efficiency and economic losses.

Description

Technical Field

[0001] The present invention belongs to the technical field of traffic operation evaluation, and in particular relates to a method for estimating traffic operation efficiency and time economic loss on a flooded road section. Background Art

[0002] Roadside flooding can negatively impact urban transportation systems in many ways. First, it slows vehicles and increases travel times. Second, it reduces road capacity, causing congestion and delays. Third, it hinders pedestrian movement and causes damage to vehicles and roads. In severe cases, road flooding can paralyze the transportation system, disrupting citizens' daily lives and travel. Therefore, estimating the traffic efficiency and time-based economic losses along flooded roads is of great research value and practical significance.

[0003] In the case of road flooding, the vehicle speed will be affected by a combination of factors such as road flooding, traffic density, and traffic flow. There is little research on how to establish a mapping relationship between the vehicle speed and the water depth at each point on the flooded road section, calculate the average delay of the section based on the water depth and the vehicle speed, and estimate the time and economic losses. This makes it difficult to provide corresponding technical support for emergency decision-making and intelligent traffic control strategies in the case of road flooding. Summary of the Invention

[0004] The main purpose of the present invention is to overcome the shortcomings and deficiencies of the existing technology, provide a method for estimating the traffic operation efficiency and time economic losses of flooded sections, realize the numerical calculation of the driving speed, travel time and delay time of flooded sections, and provide technical support for evaluating the impact of waterlogging on road traffic operation efficiency and economic losses.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] The present invention provides a method for estimating traffic operation efficiency and time economic loss in a flooded road section, comprising the following steps:

[0007] Establishing a water depth and distance relationship model, and obtaining the water depth at each point on the road section based on the water depth and distance relationship model;

[0008] Based on the depth of water at each point on the road section, calculate the free flow speed and average speed before and after the water accumulation;

[0009] Calculate the travel time before and after waterlogging to obtain the delay time caused by waterlogging on the road section;

[0010] Based on the average delay time, traffic flow, number of passengers and unit time value of each type of vehicle, the total economic loss per unit time of the flooded road section is estimated.

[0011] As a preferred technical solution, the establishment of a water depth and distance relationship model is specifically as follows:

[0012] Based on the water depth detection data, determine the relationship between the water depth x at each point on the road section and the distance l from the point to the starting point of the flooded section:

[0013] x=f(l)(0≤l≤L)

[0014] In the formula, the unit of x is cm, the unit of l is km, f represents the functional relationship of the water depth at the waterlogged location, and L represents the length of the flooded road section in km.

[0015] As a preferred technical solution, the free flow speed and average speed before and after the waterlogging are calculated based on the waterlogging depth at each point on the road section, specifically:

[0016] The congestion density of the known road section is ρ j , the unit is pcu / km, the free flow speed when there is no water is v f , in km / h, using the Greenshields flow-density-speed model to calculate the average vehicle speed v q :

[0017]

[0018] Where, v q It represents the average vehicle speed when there is no water accumulation and the traffic flow is q, in km / h. q represents the average traffic flow, in pcu / h.

[0019] Using the "hyperbolic tangent function", calculate the free flow speed v at the point where the water depth is x fx :

[0020]

[0021] Where, v fx The unit is km / h, a represents the median value of the critical water depth for vehicle stagnation, in cm, and b is the attenuation elastic coefficient;

[0022] The free flow speed v corresponding to the water depth x fx , using Greenshields flow-density-speed model to calculate the average vehicle speed v q,l :

[0023]

[0024] Where, v q,l It represents the average vehicle speed when the distance from the starting point of the flooded road section is l and the traffic flow is q, in km / h.

[0025] As a preferred technical solution, the travel time before and after the waterlogging is calculated to obtain the delay time caused by the waterlogging on the road section, specifically:

[0026] According to the length L of the flooded road section and the average vehicle speed v q , calculate the travel time t of the road section before the flooding, in hours:

[0027]

[0028] According to the average vehicle speed v after the water accumulation q,l , calculate the travel time t of the road section after flooding P , in h:

[0029]

[0030] Calculate the delay time d caused by waterlogging on the road section, in hours:

[0031] d=t P -t.

[0032] As a preferred technical solution, the total economic loss per unit time of the flooded road section is estimated based on the average delay time of each type of vehicle, traffic flow, number of passengers, and unit time value, specifically:

[0033] Based on the average delay time, traffic volume, number of passengers, and unit time value of each type of vehicle, the estimated value is:

[0034]

[0035] Where, L t It represents the total economic loss per unit time of the flooded road section, in RMB / h, n represents the number of vehicle types, d i represents the average delay time of vehicle type i, in units of h, q i The average traffic flow of vehicle type i, in pcu / h, m i Indicates the average number of passengers of vehicle type i, in person / pcu, V i It represents the average value per passenger per unit time of vehicle type i, in yuan / person / h, obtained from local economic data.

[0036] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0037] 1. The present invention takes into account the impact of road waterlogging and flow on driving speed. By establishing a model for the relationship between road waterlogging depth and distance, and using the model for the relationship between waterlogging depth and free-flow speed and the Greenshields flow-density-speed model, a method for calculating the average driving speed of vehicles on flooded road sections is proposed.

[0038] 2. The present invention provides a method for calculating the travel time and delay time of a road section under the condition of road flooding. By using the water depth-position relationship model, the numerical calculation of the driving speed, travel time and delay time of any flooded road section can be realized.

[0039] 3. The present invention provides a quantitative calculation method for traffic operation efficiency and time economic loss in flooded sections, which can take into account factors such as traffic flow, number of passengers, and unit time value, and estimate the total time economic loss per unit time in flooded sections, providing technical support for traffic management and emergency response. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0041] Figure 1 This is a flow chart of a method for estimating traffic operation efficiency and time economic loss on a flooded road section according to an embodiment of the present invention;

[0042] Figure 2 A graph showing the relationship between water depth and distance at various points on a road section according to an embodiment of the present invention;

[0043] Figure 3 This is a graph showing the relationship between water depth and free-flow speed according to an embodiment of the present invention;

[0044] Figure 4 This is a graph showing the average speed at each point on the road section according to an embodiment of the present invention. DETAILED DESCRIPTION

[0045] In order to enable those skilled in the art to better understand the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0046] References to "embodiments" in this application mean that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described in this application may be combined with other embodiments.

[0047] The embodiment selects a road section with a total length of 0.25 km as a case. It is known that the speed limit of this road section is 60 km / h and the traffic flow of a single lane in one direction is 400 pcu / h. Figure 1 A method for estimating traffic operation efficiency and time economic loss on a flooded road section is shown, and the calculation is as follows:

[0048] Step S1: establishing a waterlogging depth and distance relationship model, and obtaining the waterlogging depth of each point on the road section based on the waterlogging depth and distance relationship model.

[0049] Furthermore, step S1 is specifically as follows:

[0050] Based on the water depth detection data, the relationship between the water depth x (cm) at each point on the road section and the distance l (km) from the point to the starting point of the flooded road section is determined as follows:

[0051] x=-1056l 2 +264l (0≤l≤L) (1)

[0052] In the formula, L represents the length of the flooded road section (km). Here, the relationship between the depth of flooding and the distance at each point on the road section is as follows: Figure 2 shown.

[0053] Step S2: Calculate the free flow speed and average speed before and after the flooding according to the depth of the flooding at each point on the road section.

[0054] Furthermore, step S2 is specifically as follows:

[0055] The congestion density of the known road section is ρ j (pcu / km), the free flow speed when there is no water is v f (km / h), using the Greenshields flow-density-speed model to calculate the average vehicle speed v q :

[0056]

[0057] Where, v q represents the average vehicle speed (km / h) when there is no water accumulation and the traffic flow is q, and q represents the average traffic flow (pcu / h). Here, based on the characteristics of the road section, the congestion density ρ is known. j Take 150 pcu / km, free flow speed v f Take 60km / h, the traffic flow of a single lane is 400pcu / h, and the calculated v q It is 57.2km / h.

[0058] Use Figure 3The "hyperbolic tangent function" shown above calculates the free flow speed v at a point with a water depth of x. fx (km / h):

[0059]

[0060] Where a represents the median critical water depth for vehicle stagnation (cm), and b is the damping elastic coefficient. Based on relevant domestic data, a is set to 15 and b is set to 6.

[0061] The free flow speed v corresponding to the water depth x fx , using Greenshields flow-density-speed model to calculate the average vehicle speed v q,l :

[0062]

[0063] Where, v q,l It represents the average vehicle speed (km / h) when the distance from the starting point of the flooded road section is l and the traffic flow is q. The average speed curve of each point after the flooding is drawn as follows Figure 4 shown.

[0064] Step S3: Calculate the travel time before and after the waterlogging to obtain the delay time caused by the waterlogging on the road section.

[0065] Furthermore, step S3 is specifically as follows:

[0066] According to the length L of the flooded road section and the average vehicle speed v q , calculate the travel time t(h) of the road section before the flooding:

[0067]

[0068] Here, t is calculated to be 0.0044h, or 15.73s.

[0069] According to the average vehicle speed v after the water accumulation q,l , calculate the travel time t of the road section after flooding P (h):

[0070]

[0071] Here, it is calculated that t P It is 0.0074h, or 26.80s.

[0072] Calculate the delay time d(h) caused by waterlogging on the road section:

[0073] d=t P -t (7)

[0074] Here, d is calculated to be 0.0031h, or 11.06s.

[0075] Step S4: Estimate the total economic loss per unit time L of the flooded road section based on the average delay time, traffic flow, number of passengers, and unit time value of each type of vehicle. t (Yuan / h) is:

[0076]

[0077] Where n represents the number of vehicle types, d i represents the average delay time (h) of vehicle type i, q i represents the average traffic flow of vehicle type i (pcu / h), m i represents the average number of passengers of vehicle type i (persons / pcu), V i represents the average value per passenger per unit time of vehicle type i (yuan / person / h), which can be obtained from local economic data.

[0078] Here, only ordinary passenger cars are considered. Based on the passenger car traffic flow of 400pcu / h, the average number of passengers is 3, and the local average hourly time value per person is 55 yuan, it can be calculated that the hourly economic loss of a single lane of this section of road due to road waterlogging is 202.8 yuan.

[0079] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0080] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A method for estimating traffic operation efficiency and time economic loss in flooded road sections, characterized by: The following steps are involved: Establishing a water depth and distance relationship model, and obtaining the water depth at each point on the road section based on the water depth and distance relationship model; Based on the depth of water at each point on the road section, calculate the free flow speed and average speed before and after the water accumulation; Calculate the travel time before and after waterlogging to obtain the delay time caused by waterlogging on the road section; Estimate the total economic loss per unit time of the flooded road section based on the average delay time, traffic volume, number of passengers and unit time value of each type of vehicle; The establishment of the water depth and distance relationship model is specifically as follows: Based on the water depth detection data, determine the relationship between the water depth x at each point on the road section and the distance l from the point to the starting point of the flooded section: x=f(l)(0≤l≤L) Where x is in cm, l is in km, f is the functional relationship between the water depth at the waterlogged location, and L is the length of the flooded road section in km. The free flow speed and average speed before and after the flooding are calculated based on the depth of the flooding at each point on the road section, specifically: The congestion density of the known road section is ρ j , the unit is pcu / km, the free flow speed when there is no water is v f , in km / h, using the Greenshields flow-density-speed model to calculate the average vehicle speed v q : Where, v q It represents the average vehicle speed when there is no water accumulation and the traffic flow is q, in km / h. q represents the average traffic flow, in pcu / h. Using the "hyperbolic tangent function", calculate the free flow speed v at the point where the water depth is x fx : Where, v fx The unit is km / h, a represents the median value of the critical water depth for vehicle stagnation, in cm, and b is the attenuation elastic coefficient; The free flow speed v corresponding to the water depth x fx , using Greenshields flow-density-speed model to calculate the average vehicle speed v q,l : Where, v q,l It represents the average vehicle speed when the distance from the starting point of the flooded road section is l and the traffic flow is q, in km / h; The travel time before and after the waterlogging is calculated to obtain the delay time caused by the waterlogging on the road section, specifically: According to the length L of the flooded road section and the average vehicle speed v q , calculate the travel time t of the road section before the flooding, in hours: According to the average vehicle speed v after the water accumulation q,l , calculate the travel time t of the road section after flooding P , in h: Calculate the delay time d caused by waterlogging on the road section, in hours: d=t P -t。 2. The method for estimating traffic operation efficiency and time economic loss of a flooded road section according to claim 1 is characterized in that: The total economic loss per unit time of the flooded road section is estimated based on the average delay time of each type of vehicle, traffic flow, number of passengers, and unit time value, specifically: Based on the average delay time, traffic volume, number of passengers, and unit time value of each type of vehicle, the estimated value is: Where, L t It represents the total economic loss per unit time of the flooded road section, in RMB / h, n represents the number of vehicle types, d i represents the average delay time of vehicle type i, in units of h, q i The average traffic flow of vehicle type i, in pcu / h, m i Indicates the average number of passengers of vehicle type i, in person / pcu, V i It represents the average value per passenger per unit time of vehicle type i, in yuan / person / h, obtained from local economic data.

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